DOCUMENT AND ENTITY INFORMATION - shares	6 Months Ended
DOCUMENT AND ENTITY INFORMATION - shares	Jun. 30, 2019	Jul. 31, 2019
Document And Entity [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Fiscal Period Focus	Q2
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity Registrant Name	EVERSOURCE ENERGY
Entity Incorporation, State or Country Code	MA
Entity Central Index Key	0000072741
Entity Address, Address Line One	300 Cadwell Drive
Entity Address, City or Town	Springfield
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	01104
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-5324
Entity Tax Identification Number	04-2147929
Title of 12(b) Security	Common Shares, $5.00 par value per share
Trading Symbol	ES
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		323,602,045
The Connecticut Light and Power Company
Document And Entity [Line Items]
Current Fiscal Year End Date	--12-31
Entity Registrant Name	THE CONNECTICUT LIGHT AND POWER COMPANY
Entity Incorporation, State or Country Code	CT
Entity Central Index Key	0000023426
Entity Address, Address Line One	107 Selden Street
Entity Address, City or Town	Berlin
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06037-1616
City Area Code	800
Local Phone Number	286-5000
Entity File Number	0-00404
Entity Tax Identification Number	06-0303850
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		6,035,205
NSTAR Electric Company
Document And Entity [Line Items]
Current Fiscal Year End Date	--12-31
Entity Registrant Name	NSTAR ELECTRIC COMPANY
Entity Incorporation, State or Country Code	MA
Entity Central Index Key	0000013372
Entity Address, Address Line One	800 Boylston Street
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02199
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-02301
Entity Tax Identification Number	04-1278810
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		200
Public Service Company of New Hampshire
Document And Entity [Line Items]
Current Fiscal Year End Date	--12-31
Entity Registrant Name	PUBLIC SERVICE COMPANY OF NEW HAMPSHIRE
Entity Incorporation, State or Country Code	NH
Entity Central Index Key	0000315256
Entity Address, Address Line One	Energy Park
Entity Address, Address Line Two	780 North Commercial Street
Entity Address, City or Town	Manchester
Entity Address, State or Province	NH
Entity Address, Postal Zip Code	03101-1134
City Area Code	800
Local Phone Number	286-5000
Entity File Number	1-6392
Entity Tax Identification Number	02-0181050
Entity Filer Category	Non-accelerated Filer
Entity Smaller Reporting Company	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		301

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current Assets:
Cash	$ 20,578	$ 108,068
Receivables, Net	964,314	994,055
Unbilled Revenues	154,920	176,285
Fuel, Materials, Supplies and Inventory	174,124	238,042
Regulatory Assets	515,265	514,779
Prepayments and Other Current Assets	302,496	260,995
Total Current Assets	2,131,697	2,292,224
Property, Plant and Equipment, Net	26,304,446	25,610,428
Deferred Debits and Other Assets:
Regulatory Assets	4,404,176	4,631,137
Goodwill	4,427,266	4,427,266
Investments in Unconsolidated Affiliates	748,705	464,286
Marketable Securities	401,231	417,508
Other Long-Term Assets	578,385	398,407
Total Deferred Debits and Other Assets	10,559,763	10,338,604
Total Assets	38,995,906	38,241,256
Current Liabilities:
Notes Payable	729,000	910,000
Long-Term Debt – Current Portion	779,289	837,319
Rate Reduction Bonds – Current Portion	43,210	52,332
Accounts Payable	903,431	1,119,995
Regulatory Liabilities	379,850	370,230
Other Current Liabilities	677,341	823,006
Total Current Liabilities	3,512,121	4,112,882
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	3,549,922	3,506,030
Regulatory Liabilities	3,639,792	3,609,475
Derivative Liabilities	363,848	379,562
Accrued Pension, SERP and PBOP	955,092	962,510
Other Long-Term Liabilities	1,264,061	1,196,336
Total Deferred Credits and Other Liabilities	9,772,715	9,653,913
Long-Term Debt	13,039,180	12,248,743
Rate Reduction Bonds	561,727	583,331
Noncontrolling Interest – Preferred Stock of Subsidiaries	155,570	155,570
Common Shareholders' Equity:
Common Shares	1,699,292	1,669,392
Capital Surplus, Paid In	6,659,009	6,241,222
Retained Earnings	3,954,492	3,953,974
Accumulated Other Comprehensive Loss	(53,641)	(60,000)
Treasury Stock	(304,559)	(317,771)
Common Shareholders' Equity	11,954,593	11,486,817
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	38,995,906	38,241,256
The Connecticut Light and Power Company
Current Assets:
Cash	2,191	87,721
Receivables, Net	415,542	397,026
Accounts Receivable from Affiliated Companies	33,519	23,082
Unbilled Revenues	53,670	56,971
Fuel, Materials, Supplies and Inventory	55,243	44,529
Regulatory Assets	175,706	125,155
Prepayments and Other Current Assets	23,390	60,279
Total Current Assets	759,261	794,763
Property, Plant and Equipment, Net	9,285,633	8,909,701
Deferred Debits and Other Assets:
Regulatory Assets	1,432,827	1,505,488
Other Long-Term Assets	221,860	199,767
Total Deferred Debits and Other Assets	1,654,687	1,705,255
Total Assets	11,699,581	11,409,719
Current Liabilities:
Notes Payable to Eversource Parent	259,400	0
Long-Term Debt – Current Portion	0	250,000
Accounts Payable	287,984	324,983
Accounts Payable to Affiliated Companies	76,792	26,452
Obligations to Third Party Suppliers	52,100	56,248
Regulatory Liabilities	112,414	109,614
Derivative Liabilities	62,075	55,058
Other Current Liabilities	147,764	161,088
Total Current Liabilities	998,529	983,443
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,192,646	1,166,784
Regulatory Liabilities	1,153,360	1,122,157
Derivative Liabilities	363,717	379,536
Accrued Pension, SERP and PBOP	275,358	282,771
Other Long-Term Liabilities	153,878	155,495
Total Deferred Credits and Other Liabilities	3,138,959	3,106,743
Long-Term Debt	3,309,455	3,004,016
Noncontrolling Interest – Preferred Stock of Subsidiaries	116,200	116,200
Common Shareholders' Equity:
Common Shares	60,352	60,352
Capital Surplus, Paid In	2,410,765	2,410,765
Retained Earnings	1,664,995	1,727,899
Accumulated Other Comprehensive Loss	326	301
Common Shareholders' Equity	4,136,438	4,199,317
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	11,699,581	11,409,719
NSTAR Electric Company
Current Assets:
Cash	177	1,606
Receivables, Net	346,428	361,296
Accounts Receivable from Affiliated Companies	25,071	31,344
Unbilled Revenues	42,144	34,518
Fuel, Materials, Supplies and Inventory	64,513	114,202
Regulatory Assets	210,032	241,747
Prepayments and Other Current Assets	21,289	51,960
Total Current Assets	709,654	836,673
Property, Plant and Equipment, Net	9,075,789	8,794,700
Deferred Debits and Other Assets:
Regulatory Assets	1,178,974	1,196,512
Prepaid PBOP	146,717	132,810
Other Long-Term Assets	142,573	109,764
Total Deferred Debits and Other Assets	1,468,264	1,439,086
Total Assets	11,253,707	11,070,459
Current Liabilities:
Notes Payable	163,000	278,500
Notes Payable to Eversource Parent	40,300	0
Long-Term Debt – Current Portion	95,000	0
Accounts Payable	288,153	384,398
Accounts Payable to Affiliated Companies	72,174	89,636
Obligations to Third Party Suppliers	95,360	109,547
Renewable Portfolio Standards Compliance Obligations	66,370	139,898
Regulatory Liabilities	170,970	190,620
Other Current Liabilities	61,710	74,872
Total Current Liabilities	1,053,037	1,267,471
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	1,318,267	1,294,467
Regulatory Liabilities	1,514,845	1,513,279
Accrued Pension, SERP and PBOP	29,323	14,145
Other Long-Term Liabilities	297,346	263,096
Total Deferred Credits and Other Liabilities	3,159,781	3,084,987
Long-Term Debt	3,246,535	2,944,846
Noncontrolling Interest – Preferred Stock of Subsidiaries	43,000	43,000
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	1,653,442	1,633,442
Retained Earnings	2,099,059	2,098,091
Accumulated Other Comprehensive Loss	(1,147)	(1,378)
Common Shareholders' Equity	3,751,354	3,730,155
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	11,253,707	11,070,459
Public Service Company of New Hampshire
Current Assets:
Cash	343	1,439
Receivables, Net	99,416	104,854
Accounts Receivable from Affiliated Companies	11,476	8,444
Unbilled Revenues	39,665	47,145
Taxes Receivable	6,985	25,913
Fuel, Materials, Supplies and Inventory	23,280	37,504
Regulatory Assets	77,854	67,228
Special Deposits	35,017	47,498
Prepayments and Other Current Assets	17,293	17,564
Total Current Assets	311,329	357,589
Property, Plant and Equipment, Net	2,969,347	2,880,073
Deferred Debits and Other Assets:
Regulatory Assets	827,898	862,288
Other Long-Term Assets	32,428	27,406
Total Deferred Debits and Other Assets	860,326	889,694
Total Assets	4,141,002	4,127,356
Current Liabilities:
Notes Payable to Eversource Parent	20,100	57,000
Long-Term Debt – Current Portion	150,000	150,000
Rate Reduction Bonds – Current Portion	43,210	52,332
Accounts Payable	103,749	111,292
Accounts Payable to Affiliated Companies	27,195	26,029
Regulatory Liabilities	54,183	55,526
Other Current Liabilities	45,414	64,046
Total Current Liabilities	443,851	516,225
Deferred Credits and Other Liabilities:
Accumulated Deferred Income Taxes	496,223	481,221
Regulatory Liabilities	416,999	428,069
Accrued Pension, SERP and PBOP	107,007	124,457
Other Long-Term Liabilities	33,584	36,339
Total Deferred Credits and Other Liabilities	1,053,813	1,070,086
Long-Term Debt	951,834	655,173
Rate Reduction Bonds	561,727	583,331
Common Shareholders' Equity:
Common Shares	0	0
Capital Surplus, Paid In	678,134	678,134
Retained Earnings	453,891	627,258
Accumulated Other Comprehensive Loss	(2,248)	(2,851)
Common Shareholders' Equity	1,129,777	1,302,541
Commitments and Contingencies (Note 9)
Total Liabilities and Capitalization	$ 4,141,002	$ 4,127,356

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating Revenues	$ 1,884,495	$ 1,853,856	$ 4,300,287	$ 4,141,818
Operating Expenses:
Purchased Power, Fuel and Transmission	620,904	653,915	1,595,786	1,600,662
Operations and Maintenance	328,010	293,858	663,606	626,406
Depreciation	219,084	199,140	434,032	403,406
Amortization	38,945	36,203	109,906	81,397
Energy Efficiency Programs	105,837	101,955	245,953	236,196
Taxes Other Than Income Taxes	181,083	177,431	365,672	359,865
Impairment of Northern Pass Transmission	239,644	0	239,644	0
Total Operating Expenses	1,733,507	1,462,502	3,654,599	3,307,932
Operating Income/(Loss)	150,988	391,354	645,688	833,886
Interest Expense	132,705	126,404	264,438	247,533
Other Income, Net	45,866	50,149	76,850	83,938
Income Before Income Tax Expense	64,149	315,099	458,100	670,291
Income Tax Expense	30,815	70,452	114,209	154,219
Net Income	33,334	244,647	343,891	516,072
Net Income Attributable to Noncontrolling Interests	1,880	1,880	3,759	3,759
Net Income Attributable to Common Shareholders	$ 31,454	$ 242,767	$ 340,132	$ 512,313
Basic and Diluted Earnings Per Common Share (in dollars per share)	$ 0.10	$ 0.76	$ 1.07	$ 1.61
Weighted Average Common Shares Outstanding:
Basic (in shares)	319,664,998	317,344,596	318,644,796	317,370,825
Diluted (in shares)	320,388,490	317,885,187	319,352,287	317,939,094
The Connecticut Light and Power Company
Operating Revenues	$ 740,846	$ 694,892	$ 1,590,092	$ 1,479,875
Operating Expenses:
Purchased Power, Fuel and Transmission	246,540	234,335	566,373	536,223
Operations and Maintenance	133,351	109,685	263,989	226,977
Depreciation	74,555	69,383	147,844	136,881
Amortization of Regulatory Assets, Net	12,376	15,400	48,047	43,405
Energy Efficiency Programs	20,780	18,606	46,768	41,366
Taxes Other Than Income Taxes	86,465	84,375	178,463	174,676
Total Operating Expenses	574,067	531,784	1,251,484	1,159,528
Operating Income/(Loss)	166,779	163,108	338,608	320,347
Interest Expense	36,972	38,674	72,754	75,498
Other Income, Net	2,853	7,063	6,733	13,623
Income Before Income Tax Expense	132,660	131,497	272,587	258,472
Income Tax Expense	27,856	31,785	57,312	60,192
Net Income	104,804	99,712	215,275	198,280
NSTAR Electric Company
Operating Revenues	681,893	690,737	1,479,505	1,460,865
Operating Expenses:
Purchased Power, Fuel and Transmission	228,397	266,108	558,501	598,687
Operations and Maintenance	108,924	102,163	221,887	220,844
Depreciation	73,055	64,051	145,639	134,593
Amortization of Regulatory Assets, Net	23,184	11,954	45,768	18,318
Energy Efficiency Programs	65,904	65,184	142,633	139,978
Taxes Other Than Income Taxes	48,226	47,627	93,047	95,815
Total Operating Expenses	547,690	557,087	1,207,475	1,208,235
Operating Income/(Loss)	134,203	133,650	272,030	252,630
Interest Expense	28,238	27,359	56,120	53,822
Other Income, Net	10,657	14,269	21,743	26,870
Income Before Income Tax Expense	116,622	120,560	237,653	225,678
Income Tax Expense	26,888	32,639	53,906	60,607
Net Income	89,734	87,921	183,747	165,071
Public Service Company of New Hampshire
Operating Revenues	240,900	235,146	517,335	502,497
Operating Expenses:
Purchased Power, Fuel and Transmission	85,768	83,494	199,299	193,212
Operations and Maintenance	52,729	46,487	105,359	97,867
Depreciation	23,261	22,808	46,180	46,301
Amortization of Regulatory Assets, Net	5,857	8,926	19,523	13,961
Energy Efficiency Programs	6,215	4,674	12,929	9,831
Taxes Other Than Income Taxes	20,725	21,879	38,037	38,680
Total Operating Expenses	194,555	188,268	421,327	399,852
Operating Income/(Loss)	46,345	46,878	96,008	102,645
Interest Expense	13,909	14,612	28,276	27,386
Other Income, Net	2,984	3,409	10,006	8,159
Income Before Income Tax Expense	35,420	35,675	77,738	83,418
Income Tax Expense	8,568	9,896	18,104	22,547
Net Income	$ 26,852	$ 25,779	$ 59,634	$ 60,871

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Income	$ 33,334	$ 244,647	$ 343,891	$ 516,072
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	262		578
Qualified Cash Flow Hedging Instruments		471		1,195
Changes in Unrealized Gains/(Losses) on Marketable Securities	444	(144)	1,099	(588)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	3,457	1,815	4,682	4,808
Other Comprehensive Income, Net of Tax	4,163	2,142	6,359	5,415
Comprehensive Income Attributable to Noncontrolling Interests	(1,880)	(1,880)	(3,759)	(3,759)
Comprehensive Income Attributable to Common Shareholders	35,617	244,909	346,491	517,728
The Connecticut Light and Power Company
Net Income	104,804	99,712	215,275	198,280
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	(7)		(13)
Qualified Cash Flow Hedging Instruments		13		65
Changes in Unrealized Gains/(Losses) on Marketable Securities	15	(4)	38	(16)
Other Comprehensive Income, Net of Tax	8	9	25	49
Comprehensive Income Attributable to Common Shareholders	104,812	99,721	215,300	198,329
NSTAR Electric Company
Net Income	89,734	87,921	183,747	165,071
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	109		219
Qualified Cash Flow Hedging Instruments		109		218
Changes in Unrealized Gains/(Losses) on Marketable Securities	4	(1)	10	(5)
Changes in Funded Status of Pension, SERP and PBOP Benefit Plans	1	1	2	2
Other Comprehensive Income, Net of Tax	114	109	231	215
Comprehensive Income Attributable to Common Shareholders	89,848	88,030	183,978	165,286
Public Service Company of New Hampshire
Net Income	26,852	25,779	59,634	60,871
Other Comprehensive Income, Net of Tax:
Qualified Cash Flow Hedging Instruments	269		538
Qualified Cash Flow Hedging Instruments		277		567
Changes in Unrealized Gains/(Losses) on Marketable Securities	27	(8)	65	(29)
Other Comprehensive Income, Net of Tax	296	269	603	538
Comprehensive Income Attributable to Common Shareholders	$ 27,148	$ 26,048	$ 60,237	$ 61,409

CONDENSED CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Capital Surplus, Paid In	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	The Connecticut Light and Power Company	The Connecticut Light and Power Company Common Shares	The Connecticut Light and Power Company Capital Surplus, Paid In	The Connecticut Light and Power Company Retained Earnings	The Connecticut Light and Power Company Accumulated Other Comprehensive Loss	NSTAR Electric Company	NSTAR Electric Company Common Shares	NSTAR Electric Company Capital Surplus, Paid In	NSTAR Electric Company Retained Earnings	NSTAR Electric Company Accumulated Other Comprehensive Loss	Public Service Company of New Hampshire	Public Service Company of New Hampshire Common Shares	Public Service Company of New Hampshire Capital Surplus, Paid In	Public Service Company of New Hampshire Retained Earnings	Public Service Company of New Hampshire Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2017		316,885,808						6,035,205					200					301
Balance at Dec. 31, 2017	$ 11,086,242	$ 1,669,392	$ 6,239,940	$ 3,561,084	$ (66,403)	$ (317,771)	$ 3,587,127	$ 60,352	$ 2,110,765	$ 1,415,741	$ 269	$ 3,446,080	$ 0	$ 1,502,942	$ 1,944,961	$ (1,823)	$ 1,350,594	$ 0	$ 843,134	$ 511,382	$ (3,922)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	271,426			271,426			98,568			98,568		77,149			77,149		35,093			35,093
Dividends on Common Shares	(160,027)			(160,027)			(60,000)			(60,000)		(161,000)			(161,000)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Long-Term Incentive Plan Activity	(15,320)		(15,320)
Capital Contributions from Eversource Parent							9,000		9,000			92,500		92,500
Other												1			1
Other Comprehensive Income	3,273				3,273		40				40	106				106	269				269
Balance (in shares) at Mar. 31, 2018		316,885,808						6,035,205					200					301
Balance at Mar. 31, 2018	11,183,714	$ 1,669,392	6,224,620	3,670,603	(63,130)	(317,771)	3,633,345	$ 60,352	2,119,765	1,452,919	309	3,454,346	$ 0	1,595,442	1,860,621	(1,717)	1,385,956	$ 0	843,134	546,475	(3,653)
Balance (in shares) at Dec. 31, 2017		316,885,808						6,035,205					200					301
Balance at Dec. 31, 2017	11,086,242	$ 1,669,392	6,239,940	3,561,084	(66,403)	(317,771)	3,587,127	$ 60,352	2,110,765	1,415,741	269	3,446,080	$ 0	1,502,942	1,944,961	(1,823)	1,350,594	$ 0	843,134	511,382	(3,922)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	516,072						198,280					165,071					60,871
Dividends on Preferred Stock	(3,800)
Other Comprehensive Income	5,415						49					215					538
Balance (in shares) at Jun. 30, 2018		316,885,808						6,035,205					200					301
Balance at Jun. 30, 2018	11,273,223	$ 1,669,392	6,229,247	3,753,343	(60,988)	(317,771)	3,822,676	$ 60,352	2,210,765	1,551,241	318	3,549,886	$ 0	1,603,442	1,948,052	(1,608)	1,107,003	$ 0	538,134	572,253	(3,384)
Balance (in shares) at Mar. 31, 2018		316,885,808						6,035,205					200					301
Balance at Mar. 31, 2018	11,183,714	$ 1,669,392	6,224,620	3,670,603	(63,130)	(317,771)	3,633,345	$ 60,352	2,119,765	1,452,919	309	3,454,346	$ 0	1,595,442	1,860,621	(1,717)	1,385,956	$ 0	843,134	546,475	(3,653)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	244,647			244,647			99,712			99,712		87,921			87,921		25,779			25,779
Dividends on Common Shares	(160,027)			(160,027)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Long-Term Incentive Plan Activity	4,627		4,627
Capital Contributions from Eversource Parent							91,000		91,000			8,000		8,000			225,000		225,000
Return of Capital																	(530,000)		(530,000)
Other																	(1)			(1)
Other Comprehensive Income	2,142				2,142		9				9	109				109	269				269
Balance (in shares) at Jun. 30, 2018		316,885,808						6,035,205					200					301
Balance at Jun. 30, 2018	$ 11,273,223	$ 1,669,392	6,229,247	3,753,343	(60,988)	(317,771)	3,822,676	$ 60,352	2,210,765	1,551,241	318	3,549,886	$ 0	1,603,442	1,948,052	(1,608)	1,107,003	$ 0	538,134	572,253	(3,384)
Balance (in shares) at Dec. 31, 2018	316,885,808	316,885,808						6,035,205					200					301
Balance at Dec. 31, 2018	$ 11,486,817	$ 1,669,392	6,241,222	3,953,974	(60,000)	(317,771)	4,199,317	$ 60,352	2,410,765	1,727,899	301	3,730,155	$ 0	1,633,442	2,098,091	(1,378)	1,302,541	$ 0	678,134	627,258	(2,851)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	310,558			310,558			110,471			110,471		94,014			94,014		32,781			32,781
Dividends on Common Shares	(169,757)			(169,757)			(99,000)			(99,000)		(60,600)			(60,600)		(19,000)			(19,000)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Long-Term Incentive Plan Activity	(16,609)		(16,609)
Issuance of Treasury Shares (in shares)		461,662
Issuance of Treasury Shares	26,109		17,476			8,633
Capital Contributions from Eversource Parent												20,000		20,000
Other Comprehensive Income	2,196				2,196		17				17	117				117	307				307
Balance (in shares) at Mar. 31, 2019		317,347,470						6,035,205					200					301
Balance at Mar. 31, 2019	$ 11,637,434	$ 1,669,392	6,242,089	4,092,895	(57,804)	(309,138)	4,209,415	$ 60,352	2,410,765	1,737,980	318	3,783,196	$ 0	1,653,442	2,131,015	(1,261)	1,316,629	$ 0	678,134	641,039	(2,544)
Balance (in shares) at Dec. 31, 2018	316,885,808	316,885,808						6,035,205					200					301
Balance at Dec. 31, 2018	$ 11,486,817	$ 1,669,392	6,241,222	3,953,974	(60,000)	(317,771)	4,199,317	$ 60,352	2,410,765	1,727,899	301	3,730,155	$ 0	1,633,442	2,098,091	(1,378)	1,302,541	$ 0	678,134	627,258	(2,851)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	343,891						215,275					183,747					59,634
Dividends on Preferred Stock	(3,800)
Other Comprehensive Income	$ 6,359						25					231					603
Balance (in shares) at Jun. 30, 2019	323,574,439	323,574,439						6,035,205					200					301
Balance at Jun. 30, 2019	$ 11,954,593	$ 1,699,292	6,659,009	3,954,492	(53,641)	(304,559)	4,136,438	$ 60,352	2,410,765	1,664,995	326	3,751,354	$ 0	1,653,442	2,099,059	(1,147)	1,129,777	$ 0	678,134	453,891	(2,248)
Balance (in shares) at Mar. 31, 2019		317,347,470						6,035,205					200					301
Balance at Mar. 31, 2019	11,637,434	$ 1,669,392	6,242,089	4,092,895	(57,804)	(309,138)	4,209,415	$ 60,352	2,410,765	1,737,980	318	3,783,196	$ 0	1,653,442	2,131,015	(1,261)	1,316,629	$ 0	678,134	641,039	(2,544)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	33,334			33,334			104,804			104,804		89,734			89,734		26,852			26,852
Dividends on Common Shares	(169,857)			(169,857)			(176,400)			(176,400)		(121,200)			(121,200)		(214,000)			(214,000)
Dividends on Preferred Stock	(1,880)			(1,880)			(1,390)			(1,390)		(490)			(490)
Issuance of Common Shares (in shares)		5,980,000
Issuance of Common Shares	433,550	$ 29,900	403,650
Long-Term Incentive Plan Activity	6,470		6,470
Issuance of Treasury Shares (in shares)		246,969
Issuance of Treasury Shares	18,027		13,448			4,579
Capital Stock Expense	(6,648)		(6,648)
Other							1			1
Other Comprehensive Income	$ 4,163				4,163		8				8	114				114	296				296
Balance (in shares) at Jun. 30, 2019	323,574,439	323,574,439						6,035,205					200					301
Balance at Jun. 30, 2019	$ 11,954,593	$ 1,699,292	$ 6,659,009	$ 3,954,492	$ (53,641)	$ (304,559)	$ 4,136,438	$ 60,352	$ 2,410,765	$ 1,664,995	$ 326	$ 3,751,354	$ 0	$ 1,653,442	$ 2,099,059	$ (1,147)	$ 1,129,777	$ 0	$ 678,134	$ 453,891	$ (2,248)

CONDENSED CONSOLIDATED STATEMENTS OF COMMON SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends on Common Shares (in dollars per share)	$ 0.535	$ 0.535	$ 0.505	$ 0.505
Issuance of Common Shares, par value (in dollars per share)	$ 5

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities:
Net Income	$ 343,891	$ 516,072
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	434,032	403,406
Deferred Income Taxes	36,535	161,883
Uncollectible Expense	31,546	29,250
Pension, SERP and PBOP Expense, Net	13,227	3,317
Pension and PBOP Contributions	(6,648)	(179,002)
Regulatory (Under)/Over Recoveries, Net	23,830	36,669
Amortization	109,906	81,397
Proceeds from DOE Spent Nuclear Fuel Litigation	68,840	0
Impairment of Northern Pass Transmission	239,644	0
Other	(137,428)	(103,256)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	6,357	(52,923)
Fuel, Materials, Supplies and Inventory	63,918	65,609
Taxes Receivable/Accrued, Net	(6,883)	(132,999)
Accounts Payable	(156,077)	(80,059)
Other Current Assets and Liabilities, Net	(140,103)	(51,229)
Net Cash Flows Provided by Operating Activities	924,587	698,135
Investing Activities:
Investments in Property, Plant and Equipment	(1,377,753)	(1,251,678)
Proceeds from Sales of Marketable Securities	348,904	316,252
Purchases of Marketable Securities	(302,950)	(314,406)
Proceeds from the Sale of PSNH Generation Assets	0	116,809
Investments in Unconsolidated Affiliates	(265,955)	(13,220)
Other Investing Activities	4,055	(902)
Net Cash Flows Used in Investing Activities	(1,593,699)	(1,147,145)
Financing Activities:
Issuance of Common Shares, Net of Issuance Costs	426,902	0
Cash Dividends on Common Shares	(323,346)	(320,055)
Cash Dividends on Preferred Stock	(3,759)	(3,759)
(Decrease)/Increase in Notes Payable	(181,000)	(98,500)
Issuance of Rate Reduction Bonds	0	635,663
Repayment of Rate Reduction Bonds	(30,727)	0
Issuance of Long-Term Debt	1,000,000	1,150,000
Retirement of Long-Term Debt	(250,437)	(860,421)
Other Financing Activities	(10,682)	(17,958)
Net Cash Flows Provided by Financing Activities	626,951	484,970
Net (Decrease)/Increase in Cash and Restricted Cash	(42,161)	35,960
Cash and Restricted Cash - Beginning of Period	209,324	85,890
Cash and Restricted Cash - End of Period	167,163	121,850
The Connecticut Light and Power Company
Operating Activities:
Net Income	215,275	198,280
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	147,844	136,881
Deferred Income Taxes	16,513	50,915
Uncollectible Expense	7,627	7,747
Pension, SERP and PBOP Expense, Net	6,926	3,861
Pension Contributions	0	(41,150)
Regulatory (Under)/Over Recoveries, Net	(40,460)	(39,908)
Amortization of Regulatory Assets, Net	48,047	43,405
Other	(40,290)	(40,825)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(37,101)	(34,772)
Taxes Receivable/Accrued, Net	19,701	105
Accounts Payable	5,443	(30,805)
Other Current Assets and Liabilities, Net	(3,941)	14,377
Net Cash Flows Provided by Operating Activities	345,584	268,111
Investing Activities:
Investments in Property, Plant and Equipment	(466,112)	(457,677)
Other Investing Activities	551	110
Net Cash Flows Used in Investing Activities	(465,561)	(457,567)
Financing Activities:
Cash Dividends on Common Shares	(275,400)	(60,000)
Cash Dividends on Preferred Stock	(2,779)	(2,779)
Capital Contributions from Eversource Parent	0	100,000
Issuance of Long-Term Debt	300,000	500,000
Retirement of Long-Term Debt	(250,000)	(300,000)
Increase/(Decrease) in Notes Payable to Eversource Parent	259,400	(45,500)
Other Financing Activities	4,237	(6,189)
Net Cash Flows Provided by Financing Activities	35,458	185,532
Net (Decrease)/Increase in Cash and Restricted Cash	(84,519)	(3,924)
Cash and Restricted Cash - Beginning of Period	91,613	9,619
Cash and Restricted Cash - End of Period	7,094	5,695
NSTAR Electric Company
Operating Activities:
Net Income	183,747	165,071
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	145,639	134,593
Deferred Income Taxes	11,603	29,238
Uncollectible Expense	11,605	11,301
Pension, SERP and PBOP Income, Net	(7,052)	(19,785)
Pension and PBOP Contributions	(3,007)	(59,156)
Regulatory (Under)/Over Recoveries, Net	17,063	34,090
Amortization of Regulatory Assets, Net	45,768	18,318
Other	(36,973)	(14,646)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	(6,769)	(40,073)
Fuel, Materials, Supplies and Inventory	49,688	45,058
Taxes Receivable/Accrued, Net	25,572	(37,268)
Accounts Payable	(82,326)	(17,194)
Other Current Assets and Liabilities, Net	(103,054)	(46,861)
Net Cash Flows Provided by Operating Activities	251,504	202,686
Investing Activities:
Investments in Property, Plant and Equipment	(418,571)	(356,497)
Other Investing Activities	41	31
Net Cash Flows Used in Investing Activities	(418,530)	(356,466)
Financing Activities:
Cash Dividends on Common Shares	(181,800)	(161,000)
Cash Dividends on Preferred Stock	(980)	(980)
Capital Contributions from Eversource Parent	20,000	100,500
Increase in Notes Payable to Eversource Parent	40,300	0
(Decrease)/Increase in Notes Payable	(115,500)	213,810
Issuance of Long-Term Debt	400,000	0
Other Financing Activities	(3,287)	(158)
Net Cash Flows Provided by Financing Activities	158,733	152,172
Net (Decrease)/Increase in Cash and Restricted Cash	(8,293)	(1,608)
Cash and Restricted Cash - Beginning of Period	14,659	14,708
Cash and Restricted Cash - End of Period	6,366	13,100
Public Service Company of New Hampshire
Operating Activities:
Net Income	59,634	60,871
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	46,180	46,301
Deferred Income Taxes	12,030	41,981
Uncollectible Expense	3,100	3,200
Regulatory (Under)/Over Recoveries, Net	(29,377)	(29,816)
Amortization of Regulatory Assets, Net	19,523	13,961
Other	(7,381)	(3,428)
Changes in Current Assets and Liabilities:
Receivables and Unbilled Revenues, Net	7,658	(10,510)
Fuel, Materials, Supplies and Inventory	14,225	21,803
Taxes Receivable/Accrued, Net	18,029	(15,475)
Accounts Payable	(1,159)	(4,843)
Other Current Assets and Liabilities, Net	(17,620)	(8,050)
Net Cash Flows Provided by Operating Activities	121,742	112,795
Investing Activities:
Investments in Property, Plant and Equipment	(132,791)	(149,925)
Proceeds from the Sale of PSNH Generation Assets	0	116,809
Other Investing Activities	743	243
Net Cash Flows Used in Investing Activities	(132,048)	(32,873)
Financing Activities:
Cash Dividends on Common Shares	(233,000)	(150,000)
Capital Contributions from Eversource Parent	0	225,000
Return of Capital	0	(530,000)
Issuance of Rate Reduction Bonds	0	635,663
Repayment of Rate Reduction Bonds	(30,727)	0
Issuance of Long-Term Debt	300,000	0
Retirement of Long-Term Debt	0	(110,000)
Increase/(Decrease) in Notes Payable to Eversource Parent	(36,900)	(144,200)
Other Financing Activities	(2,703)	(75)
Net Cash Flows Provided by Financing Activities	(3,330)	(73,612)
Net (Decrease)/Increase in Cash and Restricted Cash	(13,636)	6,310
Cash and Restricted Cash - Beginning of Period	52,723	2,191
Cash and Restricted Cash - End of Period	$ 39,087	$ 8,501

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

A. Basis of Presentation

Eversource Energy is a public utility holding company primarily engaged, through its wholly-owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy's wholly-owned regulated utility subsidiaries consist of CL&P, NSTAR Electric and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight regulated utilities in Connecticut, Massachusetts and New Hampshire.

The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P are herein collectively referred to as the "financial statements."

The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, "Financial Statements and Supplementary Data," of the Eversource 2018 Form 10-K, which was filed with the SEC on February 26, 2019. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource's, CL&P's, NSTAR Electric's and PSNH's financial position as of June 30, 2019 and December 31, 2018, and the results of operations, comprehensive income and common shareholders' equity for the three and six months ended June 30, 2019 and 2018, and the cash flows for the six months ended June 30, 2019 and 2018. The results of operations and comprehensive income for the three and six months ended June 30, 2019 and 2018 and the cash flows for the six months ended June 30, 2019 and 2018 are not necessarily indicative of the results expected for a full year.

Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements.

Eversource's utility subsidiaries' electric, natural gas and water distribution and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, "Regulatory Accounting," for further information.

Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation.

B. Accounting Standards

Accounting Standards Issued but Not Yet Effective: In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. Under the new guidance, immediate recognition of all credit losses expected over the life of a financial instrument is required. The new standard also revises the other-than-temporary impairment model for available-for-sale debt securities. The standard is effective January 1, 2020, and requires a modified retrospective transition approach through a cumulative-effect adjustment to retained earnings. The Company is assessing the impacts of this standard on the accounting for credit losses on its financial instruments, including accounts receivable.

Accounting Standards Recently Adopted: On January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842), which amended existing lease accounting guidance. The Company applied the Topic 842 lease criteria to new leases and lease renewals entered into effective on or after January 1, 2019. The ASU required balance sheet recognition of leases deemed to be operating leases as well as additional disclosure requirements. The recognition, measurement and presentation of expenses and cash flows were not significantly changed.

The Company also adopted the modified retrospective transition method allowed in ASU 2018-11, Leases (Topic 842) - Targeted Improvements, which allowed the Company to adopt the new leases standard as of January 1, 2019, with prior periods presented in the financial statements continuing to follow existing lease accounting guidance under Topic 840 (Leases) in the accounting literature. Implementation of ASU 2018-11 had no effect on retained earnings, and the requirements of the new lease standard (Topic 842) are reflected in the 2019 financial statements and footnotes.

The Company elected the practical expedient package whereby it did not need to reassess whether or not an existing contract is or contains a lease or whether a lease is an operating or capital lease, and it did not need to reassess initial direct costs for leases. Election of this practical expedient allowed us to carry forward our historical lease classifications. The Company elected the practical expedient to not reevaluate land easements existing at adoption if they were not previously accounted for as leases. The Company also elected to use the discount rate as of the January 1, 2019 implementation date to discount its operating lease liabilities. The Company did not elect the hindsight practical expedient to determine the lease term for existing leases.

The Company determined the impact the ASUs had on its financial statements by reviewing its lease population and identifying lease data needed for the disclosure requirements. The Company implemented a new lease accounting system in 2019 to ensure ongoing compliance with the ASU’s requirements. Adoption of the new standard resulted in the recording of operating lease liabilities and right-of-use assets on the balance sheet upon transition at January 1, 2019 of $58.0 million at Eversource, $25.3 million at NSTAR Electric, $0.6 million at CL&P, and $0.6 million at PSNH. Implementation of the new guidance did not have an impact on each company’s results of operations or cash flows.

C. Impairment of Northern Pass Transmission

Northern Pass is Eversource's planned 1,090 MW HVDC transmission line that would interconnect from the Québec-New Hampshire border to Franklin, New Hampshire and an associated alternating current radial transmission line between Franklin and Deerfield, New Hampshire.

On March 30, 2018, the New Hampshire Site Evaluation Committee (“NHSEC”), one of the state regulatory agencies from which Northern Pass was required to obtain a siting permit, issued a written decision denying Northern Pass’ siting application. In the first quarter of 2018, Eversource conducted an impairment review of the Northern Pass project and concluded, at that time, that the recorded amount of project costs was recoverable. On July 12, 2018, the NHSEC issued a written decision denying Northern Pass’ April 2018 motion for rehearing, and on October 12, 2018, the New Hampshire Supreme Court accepted an appeal filed by Northern Pass that alleged that the NHSEC failed to follow applicable law in its review of the project. On July 19, 2019, the New Hampshire Supreme Court issued a decision denying Northern Pass’ appeal and affirming the NHSEC’s evaluation and decision that denied Northern Pass’ siting application.

Eversource evaluated the impact of the New Hampshire Supreme Court decision on the probability of construction and operation of Northern Pass. Eversource concluded that construction of the project was no longer probable and that substantially all of the capitalized project costs, which totaled $318 million, certain of which are subject to cost reimbursement agreements, were impaired. Eversource concluded that the New Hampshire Supreme Court decision is a subsequent event that required recognition in the financial statements as of and for the three and six months ended June 30, 2019.

Based on the conclusion that the construction of Northern Pass was not probable, Eversource recorded an impairment charge for all of the project costs associated with Northern Pass, which were primarily engineering design, siting, permitting and legal costs, along with appropriate allowances for funds used during construction, and recognized a receivable for certain cost reimbursement agreements. Additionally, Eversource recorded an impairment charge associated with the land acquired to construct Northern Pass in order to recognize the land at its estimated fair value based on assessed values and transaction costs. In total, this resulted in a pre-tax impairment charge of $239.6 million within Operating Income on the statement of income for the three and six months ended June 30, 2019, and was reflected in the Electric Transmission segment. The after-tax impact of the impairment charge was $204.4 million, or $0.64 per share, after giving effect to the estimated fair value of the related land, reimbursement agreements, and the impact of expected income tax benefits associated with the impairment charge. Eversource does not expect any significant estimated future cash expenditures associated with this impairment charge.

D. Provision for Uncollectible Accounts

Eversource, including CL&P, NSTAR Electric and PSNH, presents its receivables at estimated net realizable value by maintaining a provision for uncollectible accounts. This provision is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. The estimate is based upon historical collection and write-off experience and management's assessment of collectability from customers. Management continuously assesses the collectability of receivables and adjusts collectability estimates based on actual experience. Receivable balances are written off against the provision for uncollectible accounts when the customer accounts are terminated and these balances are deemed to be uncollectible.

The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows NSTAR Electric and NSTAR Gas to recover in rates amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets.

The total provision for uncollectible accounts is included in Receivables, Net on the balance sheets. The provision for uncollectible hardship accounts is included in the total uncollectible provision balance. The provision balances are as follows:



	Total Provision for Uncollectible Accounts				Provision for Uncollectible Hardship Accounts
(Millions of Dollars)	As of June 30, 2019		As of December 31, 2018		As of June 30, 2019		As of December 31, 2018
Eversource	$	226.4	$	212.7	$	137.9	$	131.5
CL&P	88.7		88.0		70.9		71.9
NSTAR Electric	81.8		74.5		47.7		42.5
PSNH	11.2		11.1		—		—

Uncollectible expense associated with customers' accounts receivable included in Operations and Maintenance expense on the statements of income is as follows:



	For the Three Months Ended				For the Six Months Ended
(Millions of Dollars)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Eversource	$	13.0	$	9.5	$	31.5	$	29.3
CL&P	3.5		3.8		7.6		7.7
NSTAR Electric	5.7		3.8		11.6		11.3
PSNH	1.4		1.5		3.1		3.2

E. Fair Value Measurements

Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" ("normal") and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill and AROs, and the estimated fair value of preferred stock, long-term debt and RRBs.

Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis, and Eversource's policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. The three levels of the fair value hierarchy are described below:

Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable.

Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products.

Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy.

Determination of Fair Value: The valuation techniques and inputs used in Eversource's fair value measurements are described in Note 4, "Derivative Instruments," Note 5, "Marketable Securities," and Note 11, "Fair Value of Financial Instruments," to the financial statements.

F. Investments in Unconsolidated Affiliates

Investments in Offshore Wind Business: Eversource's offshore wind business includes ownership interests in North East Offshore and Bay State Wind, which collectively hold power purchase agreements for the Revolution Wind and South Fork Wind projects and are in process of negotiating a power purchase agreement for the Sunrise Wind project. Eversource's offshore wind projects are being developed in partnership with Ørsted.

On February 8, 2019, Eversource and Ørsted entered into a 50-50 partnership for key offshore wind assets in the Northeast. Eversource's initial payment and contribution under the terms of the partnership agreements totaled approximately $225 million for a 50 percent interest in North East Offshore, which holds the Revolution Wind and South Fork Wind power projects, as well as a 257 square-mile lease off the coasts of Massachusetts and Rhode Island. Eversource also has a 50 percent ownership in Bay State Wind, which holds the Sunrise Wind power project. These equity investments are included in long-term assets on the balance sheet and earnings impacts are included in Other Income, Net on the statement of income. As of June 30, 2019, Eversource's total equity investment balance in its offshore wind business was $499.5 million. In July 2019, Eversource made an additional capital contribution of $54.9 million.

G. Other Income, Net

The components of Other Income, Net on the statements of income were as follows:



	For the Three Months Ended
	June 30, 2019												June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P		NSTAR Electric		PSNH
Pension, SERP and PBOP Non-Service Income/(Expense) Components	$	5.8		$	(0.9	)	$	5.4		$	1.5		$	14.6		$	2.4	$	9.5	$	2.1
AFUDC Equity	13.1			3.2			5.1			0.9			10.9			3.3		3.9		—
Equity in Earnings ⁽¹⁾	25.9			0.1			0.2			—			22.9			—		0.4		—
Investment Income/(Loss)	(0.6		)	(0.1		)	(0.3		)	(0.1		)	(0.3		)	0.4		0.3		—
Interest Income	1.3			0.5			0.2			0.7			1.9			1.0		0.2		1.3
Other	0.4			0.1			0.1			—			0.1			—		—		—
Total Other Income, Net	$	45.9		$	2.9		$	10.7		$	3.0		$	50.1		$	7.1	$	14.3	$	3.4


	For the Six Months Ended
	June 30, 2019												June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P		NSTAR Electric		PSNH
Pension, SERP and PBOP Non-Service Income/(Expense) Components	$	13.1		$	(1.6	)	$	12.4		$	2.0		$	29.8		$	5.3	$	17.9	$	4.4
AFUDC Equity	24.1			5.8			9.1			1.1			20.6			6.1		7.3		—
Equity in Earnings ⁽¹⁾	30.9			0.1			0.4			—			27.5			—		0.4		—
Investment Income/(Loss)	0.6			1.7			(0.6		)	0.2			0.4			0.2		0.9		0.1
Interest Income ⁽²⁾	7.8			0.8			0.4			6.6			5.4			2.0		0.4		3.7
Other	0.4			(0.1		)	—			0.1			0.2			—		—		—
Total Other Income, Net	$	76.9		$	6.7		$	21.7		$	10.0		$	83.9		$	13.6	$	26.9	$	8.2

⁽¹⁾Equity in earnings includes $20.4 million of unrealized gains associated with an investment in a renewable energy fund for both the three and six months ended June 30, 2019. For both the three and six months ended June 30, 2018, unrealized gains on this investment totaled $17.6 million.

⁽²⁾See Note 2, "Regulatory Accounting" for interest income recognized in 2019 for the equity return component of carrying charges on storm costs at PSNH.

H. Other Taxes

Eversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. These gross receipts taxes are recorded separately with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the statements of income as follows:



	For the Three Months Ended				For the Six Months Ended
(Millions of Dollars)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Eversource	$	36.4	$	35.6	$	81.4	$	79.0
CL&P	31.8		31.5		68.0		67.1

As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income.

Separate from above are amounts recorded as Taxes Other than Income Taxes related to the future remittance to the State of Connecticut of energy efficiency funds collected from customers in Operating Revenues. These amounts are $10.7 million and $21.4 million for the three and six months ended June 30, 2019, respectively, and $12.7 million and $25.4 million for the three and six months ended June 30, 2018, respectively. These amounts are recorded separately, with collections in Operating Revenues and with payments in Taxes Other than Income Taxes on the Eversource and CL&P statements of income.

I. Supplemental Cash Flow Information

Non-cash investing activities include plant additions included in Accounts Payable as follows:



(Millions of Dollars)	As of June 30, 2019		As of June 30, 2018
Eversource	$	323.7	$	305.7
CL&P	114.0		110.9
NSTAR Electric	85.2		71.1
PSNH	29.9		46.6

Beginning in 2019, Eversource began issuing treasury shares to satisfy awards under the Company's incentive plans, shares issued under the dividend reinvestment plan, and matching contributions under the Eversource 401k Plan. The issuance of treasury shares represents a non-cash transaction, as the treasury shares were used to fulfill Eversource's obligations that require the issuance of common shares.

The following table reconciles cash as reported on the balance sheets to the cash and restricted cash balance as reported on the statements of cash flows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Cash as reported on the Balance Sheets	$	20.6	$	2.2	$	0.2	$	0.3	$	108.1	$	87.7	$	1.6	$	1.4
Restricted cash included in:
Prepayments and Other Current Assets	54.1		4.6		6.1		35.0		72.1		3.5		13.0		47.5
Marketable Securities	20.5		0.3		0.1		0.6		25.9		0.4		0.1		0.6
Other Long-Term Assets	72.0		—		—		3.2		3.2		—		—		3.2
Cash and Restricted Cash reported on the Statements of Cash Flows	$	167.2	$	7.1	$	6.4	$	39.1	$	209.3	$	91.6	$	14.7	$	52.7

Restricted cash included in Prepayments and Other Current Assets primarily represents cash collections related to the PSNH RRB customer charges that are held in trust, and required ISO-NE cash deposits. Restricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage facilities obligations. Restricted cash included in Other Long-Term Assets at Eversource primarily relates to DOE Phase IV damages proceeds received at CYAPC and YAEC in the second quarter of 2019. See Note 9D, "Commitments and Contingencies - Spent Nuclear Fuel Obligations - Yankee Companies," for further information.

REGULATORY ACCOUNTING

6 Months Ended

Jun. 30, 2019

Regulated Operations [Abstract]

REGULATORY ACCOUNTING

Eversource's utility companies are subject to rate regulation that is based on cost recovery and meets the criteria for application of accounting guidance for rate-regulated operations, which considers the effect of regulation on the timing of the recognition of certain revenues and expenses. The regulated companies' financial statements reflect the effects of the rate-making process. The rates charged to the customers of Eversource's regulated companies are designed to collect each company's costs to provide service, including a return on investment.

Management believes it is probable that each of the regulated companies will recover its respective investments in long-lived assets, including regulatory assets. If management were to determine that it could no longer apply the accounting guidance applicable to rate-regulated enterprises to any of the regulated companies' operations, or if management could not conclude it is probable that costs would be recovered from customers in future rates, the costs would be charged to net income in the period in which the determination is made.

Regulatory Assets: The components of regulatory assets were as follows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Benefit Costs	$	1,870.5	$	407.4	$	554.8	$	151.1	$	1,914.8	$	424.7	$	544.4	$	169.6
Income Taxes, Net	702.6		456.5		104.1		10.1		728.6		454.4		105.9		8.3
Securitized Stranded Costs	586.9		—		—		586.9		608.4		—		—		608.4
Storm Restoration Costs, Net	536.7		279.6		191.2		65.9		576.0		302.6		212.9		60.5
Regulatory Tracker Mechanisms	289.0		60.3		138.2		70.6		316.0		33.2		169.1		67.3
Derivative Liabilities	347.9		345.4		—		—		356.5		356.5		—		—
Goodwill-related	340.0		—		291.9		—		348.4		—		299.1		—
Asset Retirement Obligations	97.1		33.3		48.3		3.5		89.2		32.3		42.2		3.3
Other Regulatory Assets	148.8		26.0		60.5		17.7		208.0		27.0		64.6		12.1
Total Regulatory Assets	4,919.5		1,608.5		1,389.0		905.8		5,145.9		1,630.7		1,438.2		929.5
Less: Current Portion	515.3		175.7		210.0		77.9		514.8		125.2		241.7		67.2
Total Long-Term Regulatory Assets	$	4,404.2	$	1,432.8	$	1,179.0	$	827.9	$	4,631.1	$	1,505.5	$	1,196.5	$	862.3

Storm Filings: On November 16, 2018, CL&P filed for recovery of $153 million of storm costs incurred from October 2017 through May 2018, with recovery over six years to begin May 1, 2019. Through the course of the proceeding, CL&P updated its request to $145.5 million to reflect final invoicing and capitalization amounts. On April 17, 2019, PURA authorized recovery of $141.0 million as part of storm cost recovery and the remainder to be recorded to plant or other balance sheet accounts. All approved amounts will be fully recoverable through specific mechanisms or through future rate cases.

On March 26, 2019, the NHPUC approved the recovery of $38.1 million, plus carrying charges, of storm costs incurred from December 2013 through April 2016 and the transfer of funding from PSNH’s major storm reserve to recover those costs. The costs of these storms (excluding the equity return component of the carrying charges) were deferred as regulatory assets, and the funding reserve collected from customers was accrued as a regulatory liability. As a result of the duration of time between incurring storm costs in December 2013 through April 2016 and final approval from the NHPUC in 2019, PSNH recognized $5.2 million (pre-tax) for the equity return component of the carrying charges within Other Income, Net on the statement of income in the first quarter of 2019, which has been collected from customers. Also included in the March 26, 2019 NHPUC approval is a prospective requirement for PSNH to annually net its storm funding reserve collected from customers against deferred storm costs.

In addition, on June 27, 2019, the NHPUC approved a temporary rate settlement that permits PSNH to recover approximately $68.5 million in unrecovered storm costs over a five-year period beginning August 1, 2019, with debt carrying charges.

Regulatory Costs in Long-Term Assets: Eversource's regulated companies had $142.0 million (including $43.6 million for CL&P, $61.4 million for NSTAR Electric and $15.3 million for PSNH) and $122.9 million (including $42.1 million for CL&P, $49.3 million for NSTAR Electric and $12.2 million for PSNH) of additional regulatory costs as of June 30, 2019 and December 31, 2018, respectively, that were included in long-term assets on the balance sheets. These amounts represent incurred costs for which recovery has not yet been specifically approved by the applicable regulatory agency. However, based on regulatory policies or past precedent on similar costs, management believes it is probable that these costs will ultimately be approved and recovered from customers in rates.

Regulatory Liabilities: The components of regulatory liabilities were as follows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
EDIT due to Tax Cuts and Jobs Act	$	2,860.7	$	1,028.7	$	1,090.0	$	395.4	$	2,883.0	$	1,031.0	$	1,103.7	$	396.4
Cost of Removal	544.9		51.0		319.4		21.4		521.0		39.9		307.1		22.1
Benefit Costs	83.8		—		70.9		—		91.2		—		76.9		—
Regulatory Tracker Mechanisms	333.3		110.0		141.9		31.2		309.0		89.5		163.7		48.3
AFUDC - Transmission	71.7		46.7		25.0		—		70.7		47.4		23.3		—
Revenue Subject to Refund due to Tax Cuts and Jobs Act	29.2		—		—		19.1		24.6		—		—		12.6
Other Regulatory Liabilities	96.1		29.4		38.6		4.1		80.2		24.0		29.2		4.2
Total Regulatory Liabilities	4,019.7		1,265.8		1,685.8		471.2		3,979.7		1,231.8		1,703.9		483.6
Less: Current Portion	379.9		112.4		171.0		54.2		370.2		109.6		190.6		55.5
Total Long-Term Regulatory Liabilities	$	3,639.8	$	1,153.4	$	1,514.8	$	417.0	$	3,609.5	$	1,122.2	$	1,513.3	$	428.1

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION

6 Months Ended

Jun. 30, 2019

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION

The following tables summarize property, plant and equipment by asset category:



Eversource	As of June 30, 2019			As of December 31, 2018
(Millions of Dollars)	As of June 30, 2019			As of December 31, 2018
Distribution - Electric	$	15,472.1		$	15,071.1
Distribution - Natural Gas	3,632.9			3,546.2
Transmission - Electric	10,449.5			10,153.9
Distribution - Water	1,664.1			1,639.8
Solar	196.9			164.1
Utility	31,415.5			30,575.1
Other ⁽¹⁾	882.4			778.6
Property, Plant and Equipment, Gross	32,297.9			31,353.7
Less: Accumulated Depreciation
Utility	(7,357.9		)	(7,126.2		)
Other	(363.1		)	(336.7		)
Total Accumulated Depreciation	(7,721.0		)	(7,462.9		)
Property, Plant and Equipment, Net	24,576.9			23,890.8
Construction Work in Progress	1,727.5			1,719.6
Total Property, Plant and Equipment, Net	$	26,304.4		$	25,610.4



	As of June 30, 2019									As of December 31, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Distribution - Electric	$	6,352.8		$	6,921.3		$	2,238.3		$	6,176.4		$	6,756.4		$	2,178.6
Transmission - Electric	4,880.6			4,148.8			1,415.2			4,700.5			4,065.9			1,338.7
Solar	—			196.9			—			—			164.1			—
Property, Plant and Equipment, Gross	11,233.4			11,267.0			3,653.5			10,876.9			10,986.4			3,517.3
Less: Accumulated Depreciation	(2,352.2		)	(2,814.9		)	(806.4		)	(2,302.6		)	(2,702.0		)	(772.9		)
Property, Plant and Equipment, Net	8,881.2			8,452.1			2,847.1			8,574.3			8,284.4			2,744.4
Construction Work in Progress	404.4			623.7			122.2			335.4			510.3			135.7
Total Property, Plant and Equipment, Net	$	9,285.6		$	9,075.8		$	2,969.3		$	8,909.7		$	8,794.7		$	2,880.1


⁽¹⁾	These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service.

In the second quarter of 2019, Eversource recorded an impairment charge for the NPT project costs, which had been recorded within Construction Work in Progress and also the Transmission - Electric asset category. For further information regarding the impairment of NPT, see Note 1C, "Summary of Significant Accounting Policies - Impairment of Northern Pass Transmission," to the financial statements.

DERIVATIVE INSTRUMENTS

6 Months Ended

Jun. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE INSTRUMENTS

The electric and natural gas companies purchase and procure energy and energy-related products, which are subject to price volatility, for their customers. The costs associated with supplying energy to customers are recoverable from customers in future rates. These regulated companies manage the risks associated with the price volatility of energy and energy-related products through the use of derivative and non-derivative contracts.

Many of the derivative contracts meet the definition of, and are designated as, normal and qualify for accrual accounting under the applicable accounting guidance. The costs and benefits of derivative contracts that meet the definition of normal are recognized in Operating Expenses on the statements of income, as applicable, as electricity or natural gas is delivered.

Derivative contracts that are not designated as normal are recorded at fair value as current or long-term Derivative Assets or Derivative Liabilities on the balance sheets. For the electric and natural gas companies, regulatory assets or regulatory liabilities are recorded to offset the fair values of derivatives, as contract settlement amounts are recovered from, or refunded to, customers in their respective energy supply rates.

The gross fair values of derivative assets and liabilities with the same counterparty are offset and reported as net Derivative Assets or Derivative Liabilities, with current and long-term portions, on the balance sheets. The following table presents the gross fair values of contracts, categorized by risk type, and the net amounts recorded as current or long-term derivative assets or liabilities:



		As of June 30, 2019									As of December 31, 2018
(Millions of Dollars)	Fair Value Hierarchy	Commodity Supply and Price Risk Management			Netting ⁽¹⁾			Net Amount Recorded as a Derivative			Commodity Supply and Price Risk Management			Netting ⁽¹⁾			Net Amount Recorded as a Derivative
Current Derivative Assets:
CL&P	Level 3	$	11.1		$	(0.3	)	$	10.8		$	9.6		$	(3.4	)	$	6.2
Other	Level 2	—			—			—			1.5			(0.9		)	0.6
Long-Term Derivative Assets:
CL&P	Level 3	71.8			(2.2		)	69.6			74.2			(2.3		)	71.9
Current Derivative Liabilities:
CL&P	Level 3	(62.1		)	—			(62.1		)	(55.1		)	—			(55.1		)
Other	Level 2	(2.4		)	—			(2.4		)	—			—			—
Long-Term Derivative Liabilities:
CL&P	Level 3	(363.7		)	—			(363.7		)	(379.5		)	—			(379.5		)
Other	Level 2	(0.1		)	—			(0.1		)	—			—			—


⁽¹⁾	Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists.

For further information on the fair value of derivative contracts, see Note 1E, "Summary of Significant Accounting Policies - Fair Value Measurements," to the financial statements.

Derivative Contracts at Fair Value with Offsetting Regulatory Amounts

Commodity Supply and Price Risk Management: As required by regulation, CL&P, along with UI, has capacity-related contracts with generation facilities. CL&P has a sharing agreement with UI, with 80 percent of the costs or benefits of each contract borne by or allocated to CL&P and 20 percent borne by or allocated to UI. The combined capacities of these contracts as of June 30, 2019 and December 31, 2018 are 679 MW and 787 MW, respectively. The capacity contracts extend through 2026 and obligate both CL&P and UI to make or receive payments on a monthly basis to or from the generation facilities based on the difference between a set capacity price and the capacity market price received in the ISO-NE capacity markets. In addition, CL&P has a contract to purchase 0.1 million MWh of energy per year through 2020.

As of June 30, 2019 and December 31, 2018, Eversource had New York Mercantile Exchange ("NYMEX") financial contracts for natural gas futures in order to reduce variability associated with the price of 7.1 million and 12.5 million MMBtu of natural gas, respectively.

For the three months ended June 30, 2019 and 2018, there were losses of $5.1 million and gains of $8.6 million, respectively, deferred as regulatory costs, which reflect the change in fair value associated with Eversource's derivative contracts. For the six months ended June 30, 2019 and 2018, there were losses of $10.3 million and $27.5 million, respectively.

Fair Value Measurements of Derivative Instruments

Derivative contracts classified as Level 2 in the fair value hierarchy relate to the financial contracts for natural gas futures. Prices are obtained from broker quotes and are based on actual market activity. The contracts are valued using NYMEX natural gas prices. Valuations of these contracts also incorporate discount rates using the yield curve approach.

The fair value of derivative contracts classified as Level 3 utilizes significant unobservable inputs. The fair value is modeled using income techniques, such as discounted cash flow valuations adjusted for assumptions related to exit price. Significant observable inputs for valuations of these contracts include energy and energy-related product prices in future years for which quoted prices in an active market exist. Fair value measurements categorized in Level 3 of the fair value hierarchy are prepared by individuals with expertise in valuation techniques, pricing of energy and energy-related products, and accounting requirements. The future power and capacity prices for periods that are not quoted in an active market or established at auction are based on available market data and are escalated based on estimates of inflation in order to address the full term of the contract.

Valuations of derivative contracts using a discounted cash flow methodology include assumptions regarding the timing and likelihood of scheduled payments and also reflect non-performance risk, including credit, using the default probability approach based on the counterparty's credit rating for assets and the Company's credit rating for liabilities. Valuations incorporate estimates of premiums or discounts that would be required by a market participant to arrive at an exit price, using historical market transactions adjusted for the terms of the contract.

The following is a summary of Level 3 derivative contracts and the range of the significant unobservable inputs utilized in the valuations over the duration of the contracts:



	As of June 30, 2019						As of December 31, 2018
CL&P	Range					Period Covered	Range					Period Covered
Capacity Prices	$	4.30	—	7.34	per kW-Month	2023 - 2026	$	4.30	—	7.44	per kW-Month	2022 - 2026
Forward Reserve	0.75		—	1.78	per kW-Month	2019 - 2024	0.75		—	1.78	per kW-Month	2019 - 2024

Exit price premiums of 3.1 percent through 14.6 percent are also applied to these contracts and reflect the uncertainty and illiquidity premiums that would be required based on the most recent market activity available for similar type contracts.

Significant increases or decreases in future capacity or forward reserve prices in isolation would decrease or increase, respectively, the fair value of the derivative liability. Any increases in risk premiums would increase the fair value of the derivative liability. Changes in these fair values are recorded as a regulatory asset or liability and do not impact net income.

Valuations using significant unobservable inputs: The following table presents changes in the Level 3 category of derivative assets and derivative liabilities measured at fair value on a recurring basis. The derivative assets and liabilities are presented on a net basis.



CL&P	For the Three Months Ended June 30,						For the Six Months Ended June 30,
(Millions of Dollars)	2019			2018			2019			2018
Derivatives, Net:
Fair Value as of Beginning of Period	$	(353.1	)	$	(386.5	)	$	(356.5	)	$	(362.3	)
Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets	(2.5		)	8.6			(7.8		)	(28.2		)
Settlements	10.2			8.6			18.9			21.2
Fair Value as of End of Period	$	(345.4	)	$	(369.3	)	$	(345.4	)	$	(369.3	)

MARKETABLE SECURITIES

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

MARKETABLE SECURITIES

Eversource holds marketable securities that are primarily used to fund certain non-qualified executive benefits. The trusts that hold marketable securities are not subject to regulatory oversight by state or federal agencies. CYAPC and YAEC maintain legally restricted trusts, each of which holds marketable securities, to fund the spent nuclear fuel removal obligations of their nuclear fuel storage facilities.

Equity Securities: Unrealized gains and losses on equity securities held in Eversource's non-qualified executive benefit trust are recorded in Other Income, Net on the statements of income. The fair value of these equity securities as of June 30, 2019 and December 31, 2018 was $45.2 million and $44.0 million, respectively. For the three months ended June 30, 2019 and 2018, there were unrealized gains of $2.3 million and $0.9 million, respectively, recorded in Other Income, Net related to these equity securities. For the six months ended June 30, 2019 and 2018, there were unrealized gains of $3.3 million and $0.2 million, respectively.

Eversource's equity securities also include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts, which had fair values of $158.5 million and $200.0 million as of June 30, 2019 and December 31, 2018, respectively. Unrealized gains and losses for these spent nuclear fuel trusts are subject to regulatory accounting treatment and are recorded in Marketable Securities with the corresponding offset to Other Long-Term Liabilities on the balance sheets, with no impact on the statements of income.

Available-for-Sale Debt Securities: The following is a summary of the available-for-sale debt securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets.



	As of June 30, 2019									As of December 31, 2018
Eversource (Millions of Dollars)	Amortized Cost		Pre-Tax Unrealized Gains		Pre-Tax Unrealized Losses			Fair Value		Amortized Cost		Pre-Tax Unrealized Gains		Pre-Tax Unrealized Losses			Fair Value
Debt Securities	$	204.3	$	5.4	$	(0.1	)	$	209.6	$	190.0	$	0.4	$	(4.0	)	$	186.4

Eversource's debt securities include CYAPC's and YAEC's marketable securities held in spent nuclear fuel trusts in the amounts of $172.4 million and $143.9 million as of June 30, 2019 and December 31, 2018, respectively.

Unrealized gains and losses on available-for-sale debt securities held in Eversource's non-qualified benefit trust are recorded in Accumulated Other Comprehensive Income. There have been no significant unrealized losses, other-than-temporary impairments, or credit losses for the three and six months ended June 30, 2019 and 2018. Factors considered in determining whether a credit loss exists include the duration and severity of the impairment, adverse conditions specifically affecting the issuer, and the payment history, ratings and rating changes of the security. For asset-backed debt securities, underlying collateral and expected future cash flows are also evaluated.

As of June 30, 2019, the contractual maturities of available-for-sale debt securities were as follows:



Eversource (Millions of Dollars)	Amortized Cost		Fair Value
Less than one year⁽¹⁾	$	26.9	$	26.9
One to five years	48.8		49.6
Six to ten years	38.4		40.0
Greater than ten years	90.2		93.1
Total Debt Securities	$	204.3	$	209.6


⁽¹⁾	Amounts in the Less than one year category include securities in the CYAPC and YAEC spent nuclear fuel trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets.

Realized Gains and Losses: Realized gains and losses are recorded in Other Income, Net for Eversource's benefit trust and are offset in Other Long-Term Liabilities for CYAPC and YAEC. Eversource utilizes the specific identification basis method for the Eversource non-qualified benefit trust, and the average cost basis method for the CYAPC and YAEC spent nuclear fuel trusts to compute the realized gains and losses on the sale of marketable securities.

Fair Value Measurements: The following table presents the marketable securities recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy:



Eversource (Millions of Dollars)	As of June 30, 2019		As of December 31, 2018
Level 1:
Mutual Funds and Equities	$	203.7	$	244.0
Money Market Funds	20.5		25.9
Total Level 1	$	224.2	$	269.9
Level 2:
U.S. Government Issued Debt Securities (Agency and Treasury)	$	107.0	$	79.6
Corporate Debt Securities	46.1		39.5
Asset-Backed Debt Securities	13.4		14.0
Municipal Bonds	12.8		19.2
Other Fixed Income Securities	9.8		8.2
Total Level 2	$	189.1	$	160.5
Total Marketable Securities	$	413.3	$	430.4

U.S. government issued debt securities are valued using market approaches that incorporate transactions for the same or similar bonds and adjustments for yields and maturity dates. Corporate debt securities are valued using a market approach, utilizing recent trades of the same or similar instruments and also incorporating yield curves, credit spreads and specific bond terms and conditions. Asset-backed debt securities include collateralized mortgage obligations, commercial mortgage backed securities, and securities collateralized by auto loans, credit card loans or receivables. Asset-backed debt securities are valued using recent trades of similar instruments, prepayment assumptions, yield curves, issuance and maturity dates, and tranche information. Municipal bonds are valued using a market approach that incorporates reported trades and benchmark yields. Other fixed income securities are valued using pricing models, quoted prices of securities with similar characteristics, and discounted cash flows.

SHORT-TERM AND LONG-TERM DEBT

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

SHORT-TERM AND LONG-TERM DEBT

Short-Term Debt - Commercial Paper Programs and Credit Agreements: Eversource parent has a $1.45 billion commercial paper program allowing Eversource parent to issue commercial paper as a form of short-term debt. Eversource parent, CL&P, PSNH, NSTAR Gas and Yankee Gas are also parties to a five-year $1.45 billion revolving credit facility, which terminates on December 8, 2023. The revolving credit facility serves to backstop Eversource parent's $1.45 billion commercial paper program.

NSTAR Electric has a $650 million commercial paper program allowing NSTAR Electric to issue commercial paper as a form of short-term debt. NSTAR Electric is also a party to a five-year $650 million revolving credit facility, which terminates on December 8, 2023. The revolving credit facility serves to backstop NSTAR Electric's $650 million commercial paper program.

The amount of borrowings outstanding and available under the commercial paper programs were as follows:



	Borrowings Outstanding as of				Available Borrowing Capacity as of				Weighted-Average Interest Rate as of
	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
(Millions of Dollars)	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
Eversource Parent Commercial Paper Program	$	566.0	$	631.5	$	884.0	$	818.5	2.55	%	2.77	%
NSTAR Electric Commercial Paper Program	163.0		278.5		487.0		371.5		2.42	%	2.50	%

There were no borrowings outstanding on either the Eversource parent or NSTAR Electric revolving credit facilities as of June 30, 2019 or December 31, 2018. Eversource's water distribution segment has a $100 million revolving credit facility, which expires on August 19, 2019, and there were no borrowings outstanding as of June 30, 2019 or December 31, 2018.

Amounts outstanding under the commercial paper programs and revolving credit facility are included in Notes Payable and are classified in current liabilities on the Eversource and NSTAR Electric balance sheets as all borrowings are outstanding for no more than 364 days at one time.

We expect the future operating cash flows of Eversource, CL&P, NSTAR Electric and PSNH, along with our existing borrowing availability and access to both debt and equity markets, will be sufficient to meet any working capital and future operating requirements, and capital investment forecasted opportunities.

Intercompany Borrowings: Eversource parent uses its available capital resources to provide loans to its subsidiaries to assist them in meeting their short-term borrowing needs. In addition, growth in Eversource's key business initiatives requires cash infusion to those subsidiaries. Eversource parent records intercompany interest income from its loans to subsidiaries, which is eliminated in consolidation. Intercompany loans from Eversource parent to its subsidiaries are eliminated in consolidation on Eversource's balance sheets. As of June 30, 2019, there were intercompany loans from Eversource parent to CL&P of $259.4 million, to PSNH of $20.1 million, and to Harbor Electric Energy Company, a wholly-owned subsidiary of NSTAR Electric ("HEEC"), of $40.3 million. As of December 31, 2018, there were intercompany loans from Eversource parent to PSNH of $57.0 million. Intercompany loans from Eversource parent are included in Notes Payable to Eversource Parent and are classified in current liabilities on the respective subsidiary's balance sheets.

Long-Term Debt Issuance Authorization: On April 26, 2019, the NHPUC approved PSNH’s request for authorization to issue up to $300 million in long-term debt through December 31, 2019.

Long-Term Debt: The following table summarizes long-term debt issuances and repayments:



(Millions of Dollars)	Issue Date	Issuance/(Repayment)			Maturity Date	Use of Proceeds for Issuance/ Repayment Information
CL&P:
4.00% 2018 Series A First Mortgage Bonds ⁽¹⁾	April 2019	$	300.0		April 2048	Repaid short-term borrowings that were used to repay long-term debt that matured on February 1, 2019 and fund capital expenditures and working capital
5.50% 2009 Series A First Mortgage Bonds	February 2009	(250.0		)	February 2019	Repaid at maturity on February 1, 2019
NSTAR Electric:
3.25% 2019 Debentures	May 2019	400.0			May 2029	Repaid short-term borrowings that were used to fund investments in eligible green expenditures
PSNH:
3.60% 2019 Series T First Mortgage Bonds	June 2019	300.0			July 2049	Repay long-term debt due to mature in December 2019, repaid short-term borrowings and fund capital expenditures and working capital
Other:
NSTAR Gas 3.74% Series Q First Mortgage Bonds	July 2019	75.0			August 2049	Repaid short-term borrowings and fund capital expenditures and working capital


⁽¹⁾	These bonds are part of the same series issued by CL&P in March 2018. The aggregate outstanding principal amount of these bonds is now $800 million.

As a result of the NSTAR Gas debt issuance in July 2019, $75 million of current portion of long-term debt was reclassified to Long-Term Debt on Eversource's consolidated balance sheet as of June 30, 2019.

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES

6 Months Ended

Jun. 30, 2019

Rate Reduction Bonds and Variable Interest Entity [Abstract]

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES

Rate Reduction Bonds: On May 8, 2018, PSNH Funding, a wholly-owned subsidiary of PSNH, issued $635.7 million of securitized RRBs in multiple tranches with a weighted average interest rate of 3.66 percent, and final maturity dates ranging from 2026 to 2035. The RRBs are expected to be repaid by February 1, 2033. RRB payments consist of principal and interest and will be paid semi-annually, beginning on February 1, 2019. The RRBs were issued pursuant to a finance order issued by the NHPUC on January 30, 2018 to recover remaining costs resulting from the divestiture of PSNH’s generation assets.

PSNH Funding is considered a VIE primarily because the equity capitalization is insufficient to support its operations. PSNH has the power to direct the significant activities of the VIE and is most closely associated with the VIE as compared to other interest holders. Therefore, PSNH is considered the primary beneficiary and consolidates PSNH Funding in its consolidated financial statements. The following tables summarize the impact of PSNH Funding on PSNH's balance sheets and income statements:



(Millions of Dollars)
Balance Sheet:	As of June 30, 2019		As of December 31, 2018
Restricted Cash - Current Portion (included in Prepayments and Other Current Assets)	$	35.0	$	47.5
Restricted Cash - Long-Term Portion (included in Other Long-Term Assets)	3.2		3.2
Securitized Stranded Costs (included in Regulatory Assets)	586.9		608.4
Other Regulatory Liabilities (included in Regulatory Liabilities)	7.9		5.8
Accrued Interest (included in Other Current Liabilities)	8.9		14.4
Rate Reduction Bonds - Current Portion	43.2		52.3
Rate Reduction Bonds - Long-Term Portion	561.7		583.3



(Millions of Dollars)	For the Three Months Ended				For the Six Months Ended
Income Statement:	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	$	10.8	$	6.8	$	21.5	$	6.8
Interest Expense on RRB Principal (included in Interest Expense)	5.3		2.8		10.7		2.8

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION

6 Months Ended

Jun. 30, 2019

Postemployment Benefits [Abstract]

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION

Eversource provides defined benefit retirement plans ("Pension Plans") that cover eligible employees. In addition to the Pension Plans, Eversource maintains non-qualified defined benefit retirement plans ("SERP Plans"), which provide benefits in excess of Internal Revenue Code limitations to eligible participants consisting of current and retired employees. Eversource also provides defined benefit postretirement plans ("PBOP Plans") that provide life insurance and a health reimbursement arrangement created for the purpose of reimbursing retirees and dependents for health insurance premiums and certain medical expenses to eligible employees that meet certain age and service eligibility requirements.

The components of net periodic benefit expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets for future recovery, are shown below. The service cost component of net periodic benefit expense, less the capitalized portion, is included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense/(income), less the deferred portion, are included in Other Income, Net on the statements of income. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric and PSNH does not include the intercompany allocations or the corresponding capitalized and deferred portion, as these amounts are cash settled on a short-term basis.



	Pension and SERP
	For the Three Months Ended June 30, 2019												For the Three Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	16.1		$	4.4		$	3.6		$	1.5		$	20.7		$	5.2		$	4.3		$	2.7
Interest Cost	54.8			11.4			12.3			6.0			49.1			10.5			10.9			5.5
Expected Return on Pension Plan Assets	(91.7		)	(18.1		)	(24.2		)	(10.1		)	(97.9		)	(19.4		)	(26.6		)	(10.8		)
Actuarial Loss	35.6			6.3			11.8			2.3			35.7			7.1			10.1			3.3
Prior Service Cost	0.3			—			—			—			2.1			0.2			0.1			0.1
Total Net Periodic Benefit Expense/(Income)	$	15.1		$	4.0		$	3.5		$	(0.3	)	$	9.7		$	3.6		$	(1.2	)	$	0.8
Intercompany Allocations	N/A			$	5.8		$	5.3		$	—		N/A			$	1.5		$	1.6		$	0.5

	Pension and SERP
	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	35.4		$	9.2		$	7.5		$	4.1		$	43.1		$	11.0		$	9.0		$	5.7
Interest Cost	109.1			23.0			24.2			12.2			97.8			20.9			21.7			10.9
Expected Return on Pension Plan Assets	(183.8		)	(36.9		)	(48.6		)	(20.4		)	(195.8		)	(40.2		)	(51.8		)	(21.8		)
Actuarial Loss	72.1			14.3			21.2			5.9			71.8			14.8			20.7			6.5
Prior Service Cost	0.6			—			0.1			—			4.1			0.6			0.1			0.2
Total Net Periodic Benefit Expense/(Income)	$	33.4		$	9.6		$	4.4		$	1.8		$	21.0		$	7.1		$	(0.3	)	$	1.5
Intercompany Allocations	N/A			$	13.6		$	8.4		$	2.5		N/A			$	3.0		$	3.2		$	1.0



	PBOP
	For the Three Months Ended June 30, 2019												For the Three Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	1.8		$	0.3		$	0.4		$	0.1		$	2.5		$	0.4		$	0.5		$	0.3
Interest Cost	8.2			1.6			2.4			0.8			6.8			1.5			2.2			0.9
Expected Return on Plan Assets	(16.8		)	(2.3		)	(7.5		)	(1.3		)	(16.7		)	(2.6		)	(8.1		)	(1.5		)
Actuarial Loss	1.6			0.3			0.7			—			1.6			0.4			0.4			0.2
Prior Service Cost/(Credit)	(5.8		)	0.3			(4.2		)	0.1			(5.7		)	0.3			(4.3		)	0.1
Total Net Periodic Benefit Expense/(Income)	$	(11.0	)	$	0.2		$	(8.2	)	$	(0.3	)	$	(11.5	)	$	—		$	(9.3	)	$	—
Intercompany Allocations	N/A			$	(0.3	)	$	(0.4	)	$	(0.1	)	N/A			$	(0.2	)	$	(0.3	)	$	(0.1	)

	PBOP
	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	3.9		$	0.7		$	0.9		$	0.4		$	5.0		$	0.9		$	1.0		$	0.6
Interest Cost	16.3			3.1			4.7			1.7			14.4			2.9			4.4			1.6
Expected Return on Plan Assets	(33.4		)	(4.5		)	(15.1		)	(2.8		)	(34.8		)	(5.2		)	(16.2		)	(3.0		)
Actuarial Loss	4.1			0.7			1.7			0.2			4.4			0.8			1.1			0.4
Prior Service Cost/(Credit)	(11.6		)	0.5			(8.5		)	0.2			(11.5		)	0.5			(8.5		)	0.3
Total Net Periodic Benefit Expense/(Income)	$	(20.7	)	$	0.5		$	(16.3	)	$	(0.3	)	$	(22.5	)	$	(0.1	)	$	(18.2	)	$	(0.1	)
Intercompany Allocations	N/A			$	(0.4	)	$	(0.6	)	$	(0.2	)	N/A			$	(0.5	)	$	(0.7	)	$	(0.2	)

COMMITMENTS AND CONTINGENCIES

6 Months Ended

Jun. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

COMMITMENTS AND CONTINGENCIES

A. Environmental Matters

Eversource, CL&P, NSTAR Electric and PSNH are subject to environmental laws and regulations intended to mitigate or remove the effect of past operations and improve or maintain the quality of the environment. These laws and regulations require the removal or the remedy of the effect on the environment of the disposal or release of certain specified hazardous substances at current and former operating sites. Eversource, CL&P, NSTAR Electric and PSNH have an active environmental auditing and training program and each believes it is substantially in compliance with all enacted laws and regulations.

The number of environmental sites and related reserves for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows:



	As of June 30, 2019			As of December 31, 2018
	Number of Sites	Reserve (in millions)		Number of Sites	Reserve (in millions)
Eversource	58	$	71.6	60	$	64.7
CL&P	15	5.8		15	5.4
NSTAR Electric	15	10.5		16	10.9
PSNH	9	5.4		9	5.4

Included in the number of sites and reserve amounts above are former MGP sites that were operated several decades ago and manufactured gas from coal and other processes, which resulted in certain by-products remaining in the environment that may pose a potential risk to human health and the environment, for which Eversource may have potential liability. The reserve balances related to these former MGP sites were $57.1 million and $50.1 million as of June 30, 2019 and December 31, 2018, respectively, and related primarily to the natural gas business segment.

These reserve estimates are subjective in nature as they take into consideration several different remediation options at each specific site. The reliability and precision of these estimates can be affected by several factors, including new information concerning either the level of contamination at the site, the extent of Eversource's, CL&P's, NSTAR Electric's and PSNH's responsibility for remediation or the extent of remediation required, recently enacted laws and regulations or changes in cost estimates due to certain economic factors. It is possible that new information or future developments could require a reassessment of the potential exposure to required environmental remediation. As this information becomes available, management will continue to assess the potential exposure and adjust the reserves accordingly.

B. Long-Term Contractual Arrangements

On December 28, 2018, under Public Act 17-3, "An Act Concerning Zero Carbon Procurement," DEEP selected the Millstone Nuclear Power Station generation facility, along with smaller generation facilities, in DEEP’s zero-carbon request for proposal. CL&P and UI were directed by DEEP to enter into ten-year contracts to purchase a combined total of approximately 9 million MWh annually from the Millstone generation facility. On March 15, 2019, CL&P and UI each signed a ten-year contract with the owner of Millstone Nuclear Power Station in order to purchase a combined amount of approximately 50 percent of the facility's output (approximately 40 percent by CL&P). The Millstone Nuclear Power Station has a 2,112 MW nameplate capacity. The parties filed the contract with PURA on March 29, 2019 for review and approval. A decision from PURA is expected in the third quarter of 2019.

The significant output of the generation facility, the contract period, and the pricing will result in a significant multi-billion dollar contractual commitment. We plan to sell the energy purchased under this contract into the market and use the proceeds from these energy sales to offset the contract costs. As the net costs under this contract will be recovered from customers in future rates, the contract will not have an impact on the net income of CL&P.

C. Guarantees and Indemnifications

In the normal course of business, Eversource parent provides credit assurances on behalf of its subsidiaries, including CL&P, NSTAR Electric and PSNH, in the form of guarantees.

Eversource parent issued a guaranty on behalf of its subsidiary, NPT, under which, beginning at the time the Northern Pass Transmission line would go into commercial operation, Eversource parent would guarantee the financial obligations of NPT under the TSA with HQ in an amount not to exceed $25 million. Eversource parent's obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations. Eversource parent also entered into a guaranty on behalf of NPT under which Eversource parent would guarantee NPT's obligations under a facility with a financial institution pursuant to which NPT may request letters of credit in an aggregate amount of up to approximately $14 million. In the second quarter of 2019, Eversource concluded that construction of the NPT project was no longer probable. For further information regarding the impairment of NPT, see Note 1C, "Summary of Significant Accounting Policies - Impairment of Northern Pass Transmission," to the financial statements. While these guarantees are currently outstanding, it is expected that they will be extinguished pending the final dissolution of NPT.

Management does not anticipate a material impact to net income or cash flows as a result of these various guarantees and indemnifications. The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries to external parties, as of June 30, 2019:



Company	Description	Maximum Exposure (in millions)		Expiration Dates
On behalf of subsidiaries:
Eversource Investment LLC	North East Offshore ⁽¹⁾	$	113.9	-
Various	Surety Bonds⁽²⁾	34.0		2019 - 2021
Rocky River Realty Company and Eversource Service	Lease Payments for Real Estate	7.1		2024
Bay State Wind	Real Estate Purchase	2.5		2020

⁽¹⁾

Eversource parent issued a declining balance guaranty on behalf of its subsidiary, Eversource Investment LLC, which holds an ownership interest in North East Offshore. Eversource parent will guarantee, as a primary obligor, the financial obligations, primarily all post-closing payment obligations of Eversource Investment LLC, under the Sale and Purchase Agreement and an Irrevocable Equity Commitment Letter with Ørsted. Eversource parent's obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations.


⁽²⁾	Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded.

D. Spent Nuclear Fuel Obligations - Yankee Companies

CL&P, NSTAR Electric and PSNH have plant closure and fuel storage cost obligations to the Yankee Companies, which have each completed the physical decommissioning of their respective nuclear facilities and are now engaged in the long-term storage of their spent fuel. The Yankee Companies fund these costs through litigation proceeds received from the DOE and, to the extent necessary, through wholesale, FERC-approved rates charged under power purchase agreements with several New England utilities, including CL&P, NSTAR Electric and PSNH. CL&P, NSTAR Electric and PSNH, in turn recover these costs from their customers through state regulatory commission-approved retail rates. The Yankee Companies collect amounts that management believes are adequate to recover the remaining plant closure and fuel storage cost estimates for the respective plants. Management believes CL&P and NSTAR Electric will recover their shares of these obligations from their customers. PSNH has recovered its total share of these costs from its customers.

Spent Nuclear Fuel Litigation:

The Yankee Companies have filed complaints against the DOE in the Court of Federal Claims seeking monetary damages resulting from the DOE's failure to provide for a permanent facility to store spent nuclear fuel pursuant to the terms of the 1983 spent fuel and high level waste disposal contracts between the Yankee Companies and the DOE. The court had previously awarded the Yankee Companies damages for Phase I, II and III of litigation resulting from the DOE's failure to meet its contractual obligations. These Phases covered damages incurred in the years 1998 through 2012, and the awarded damages have been received by the Yankee Companies with certain amounts of the damages refunded to their customers.

DOE Phase IV Damages - On May 22, 2017, each of the Yankee Companies filed subsequent lawsuits against the DOE in the Court of Federal

Claims. The Yankee Companies sought monetary damages totaling $104.4 million for CYAPC, YAEC and MYAPC, resulting from the DOE's failure to begin accepting spent nuclear fuel for disposal covering the years from 2013 to 2016 (“DOE Phase IV”). On February 21, 2019, the Yankee Companies received a partial summary judgment and partial final judgment in their favor for the undisputed amount of monetary damages of $103.2 million. The court awarded CYAPC, YAEC and MYAPC damages of $40.7 million, $28.1 million and $34.4 million, respectively. The DOE did not appeal the court's judgment and the decision became final on April 23, 2019. On June 12, 2019, CYAPC and YAEC received damages of $40.7 million and $28.1 million, respectively, which were recorded as restricted cash within Other Long-Term Assets on the Eversource consolidated balance sheet as of June 30, 2019.

The Yankee Companies are in the process of preparing a required informational filing with FERC as to the use of proceeds. At this time, the damages are primarily expected to be used by the Yankee Companies to fund remaining fuel storage obligations, and management does not expect significant amounts to be refunded to Eversource utilities (CL&P, NSTAR Electric and PSNH). The utilities would then ultimately refund any amounts received to utility customers.

On June 12, 2019, the court accepted an offer of judgment in the amount of $0.5 million to settle the disputed amount of approximately $1 million in Phase IV contested damages. The Yankee Companies received the $0.5 million payment in July 2019.

E. FERC ROE Complaints

Four separate complaints have been filed at the FERC by combinations of New England state attorneys general, state regulatory commissions, consumer advocates, consumer groups, municipal parties and other parties (collectively the "Complainants"). In each of the first three complaints, filed on October 1, 2011, December 27, 2012, and July 31, 2014, respectively, the Complainants challenged the NETOs' base ROE of 11.14 percent that had been utilized since 2005 and sought an order to reduce it prospectively from the date of the final FERC order and for the separate 15-month complaint periods. In the fourth complaint, filed April 29, 2016, the Complainants challenged the NETOs' base ROE billed of 10.57 percent and the maximum ROE for transmission incentive ("incentive cap") of 11.74 percent, asserting that these ROEs were unjust and unreasonable.

The ROE originally billed during the period October 1, 2011 (beginning of the first complaint period) through October 15, 2014 consisted of a base ROE of 11.14 percent and incentives up to 13.1 percent. On October 16, 2014, the FERC set the base ROE at 10.57 percent and the incentive cap at 11.74 percent for the first complaint period. This was also effective for all prospective billings to customers beginning October 16, 2014. This FERC order was vacated on April 14, 2017 by the U.S. Court of Appeals for the D.C. Circuit (the "Court").

All amounts associated with the first complaint period have been refunded, which totaled $38.9 million (pre-tax and excluding interest) at Eversource and reflected both the base ROE and incentive cap prescribed by the FERC order. The refund consisted of $22.4 million for CL&P, $13.7 million for NSTAR Electric and $2.8 million for PSNH.

Eversource has recorded a reserve of $39.1 million (pre-tax and excluding interest) for the second complaint period as of June 30, 2019. This reserve represents the difference between the billed rates during the second complaint period and a 10.57 percent base ROE and 11.74 percent incentive cap. The reserve consisted of $21.4 million for CL&P, $14.6 million for NSTAR Electric and $3.1 million for PSNH as of June 30, 2019.

On October 16, 2018, FERC issued an order on all four complaints describing how it intends to address the issues that were remanded by the Court. FERC proposed a new framework to determine (1) whether an existing ROE is unjust and unreasonable and, if so, (2) how to calculate a replacement ROE. The parties to these proceedings were directed to submit briefs on this new proposed framework and how they would apply the proposed framework in each of the four complaint proceedings. Initial briefs were filed by the NETOs, Complainants and FERC Trial Staff on January 11, 2019 and reply briefs were filed on March 8, 2019. The NETOs' brief was supportive of the overall ROE methodology determined in the October 16, 2018 order provided the FERC does not change the proposed methodology or alter its implementation in a manner that has a material impact on the results.

The FERC order included illustrative calculations for the first complaint using FERC's proposed frameworks with financial data from that complaint. Those preliminary calculations indicated that for the first complaint period, for the NETOs that FERC concludes are of average financial risk, (1) a preliminary range of presumptively just and reasonable base ROEs is 9.60 percent to 10.99 percent; (2) the pre-existing base ROE of 11.14 percent is therefore unjust and unreasonable; (3) the preliminary just and reasonable base ROE is 10.41 percent; and (4) the preliminary incentive cap on total ROE is 13.08 percent.

If the results of these illustrative calculations were included in a final FERC order for each of the complaint periods, then a 10.41 percent base ROE and a 13.08 percent incentive cap would not have a significant impact on our financial statements for all of the complaint periods.

Although the order provided illustrative calculations, FERC stated that these calculations are merely preliminary. The FERC’s preliminary calculations are not binding and do not represent what we believe to be the most likely outcome of a final FERC order, as changes to the methodology by FERC are possible as a result of the parties’ arguments and calculations in the briefing process. Until FERC issues a final decision on each of these four complaints, there is significant uncertainty, and at this time, the Company cannot reasonably estimate a range of gain or loss for any of the four complaint proceedings. The October 16, 2018 FERC order or the 2019 briefs did not provide a reasonable basis for a change to the reserve or recognized ROEs for any of the complaint periods.

Eversource, CL&P, NSTAR Electric and PSNH currently record revenues at the 10.57 percent base ROE and incentive cap at 11.74 percent established in the October 16, 2014 FERC order.

The average impact of a 10 basis point change to the base ROE for each of the 15-month complaint periods would affect Eversource's after-tax earnings by approximately $3 million.

F. Eversource and NSTAR Electric Boston Harbor Civil Action

On July 15, 2016, the United States Attorney on behalf of the United States Army Corps of Engineers filed a civil action in the United States District Court for the District of Massachusetts under provisions of the Rivers and Harbors Act of 1899 and the Clean Water Act against NSTAR Electric, HEEC, and the Massachusetts Water Resources Authority (together with NSTAR Electric and HEEC, the "Defendants"). The action alleged that the Defendants failed to comply with certain permitting requirements related to the placement of the HEEC-owned electric distribution cable beneath Boston Harbor. The action sought an order to compel HEEC to comply with cable depth requirements in the United States Army Corps of Engineers' permit or alternatively to remove the electric distribution cable and cease unauthorized work in U.S. waterways. The action also sought civil penalties and other costs.

The parties reached a settlement pursuant to which HEEC agreed to install a new 115kV distribution cable across Boston Harbor to Deer Island, utilizing a different route, and remove portions of the existing cable. Upon the installation and completion of the new cable and the removal of the portions of the existing cable, all issues surrounding the current permit from the United States Army Corps of Engineers are expected to be resolved, and such litigation is expected to be dismissed with prejudice.

NSTAR Electric agreed to provide a rate base credit of $17.5 million to the Massachusetts Water Resources Authority for the new cable. This negotiated credit resulted in the initial $17.5 million of construction costs on the new cable being expensed as incurred, all of which was fully expensed in 2018. Construction of the new cable is underway and is expected to be completed in 2019.

LEASES

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

LEASES

Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term.

Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated.

The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years. The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options.

For leases entered into or modified after the January 1, 2019 implementation date, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease, as the rate implicit in the lease is not determinable.

CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts are included as variable lease cost in the table below. The expense and long-term obligation for these contracts are included in the annually reported contractual obligations table in Note 12B, "Commitments and Contingencies - Long-Term Contractual Arrangements," of the Eversource 2018 Form 10-K.

The components of lease cost, prior to amounts capitalized, are as follows:



	For the Three Months Ended June 30, 2019								For the Six Months Ended June 30, 2019
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Financing Lease Cost:
Amortization of Right-of-use-Assets	$	0.4	$	0.2	$	—	$	—	$	0.7	$	0.4	$	0.1	$	—
Interest on Lease Liabilities	0.3		0.1		0.2		—		0.7		0.3		0.3		—
Total Finance Lease Cost	0.7		0.3		0.2		—		1.4		0.7		0.4		—
Operating Lease Cost	2.9		0.1		0.5		—		5.9		0.1		0.9		—
Variable Lease Cost	15.7		3.1		—		12.6		31.1		6.5		—		24.6
Total Lease Cost	$	19.3	$	3.5	$	0.7	$	12.6	$	38.4	$	7.3	$	1.3	$	24.6

Operating lease cost, less the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Fuel and Transmission expense for transmission segment leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense, Net on the statements of income.

Supplemental balance sheet information related to leases is as follows:



		As of June 30, 2019
(Millions of Dollars)	Balance Sheet Classification	Eversource		CL&P		NSTAR Electric		PSNH
Operating Leases:
Operating Lease Right-of-use-Assets, Net	Other Long-Term Assets	$	54.6	$	0.6	$	24.4	$	0.8
Operating Lease Liabilities
Operating Lease Liabilities - Current Portion	Other Current Liabilities	$	8.8	$	0.2	$	0.5	$	0.2
Operating Lease Liabilities - Long-Term	Other Long-Term Liabilities	45.8		0.4		23.9		0.6
Total Operating Lease Liabilities		$	54.6	$	0.6	$	24.4	$	0.8
Finance Leases:
Finance Lease Right-of-use-Assets, Net	Property, Plant and Equipment, Net	$	9.4	$	2.6	$	3.4	$	0.9
Finance Lease Liabilities
Finance Lease Liabilities - Current Portion	Other Current Liabilities	$	2.3	$	1.5	$	—	$	0.1
Finance Lease Liabilities - Long-Term	Other Long-Term Liabilities	9.3		2.3		4.4		0.8
Total Finance Lease Liabilities		$	11.6	$	3.8	$	4.4	$	0.9

The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability.

Other information related to leases is as follows (in millions of dollars, unless otherwise noted):



	Eversource			CL&P			NSTAR Electric			PSNH
As of June 30, 2019
Weighted-Average Remaining Lease Term (Years):
Operating Leases	12			4			21			8
Financing Leases	11			2			23			9
Weighted-Average Discount Rate (Percentage):
Operating Leases	3.9		%	2.7		%	4.1		%	3.6		%
Financing Leases	4.3		%	10.5		%	2.9		%	3.5		%

For the Three Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	3.0		$	0.1		$	0.5		$	—
Operating Cash Flows from Finance Leases	0.3			0.1			0.1			—
Financing Cash Flows from Finance Leases	0.5			0.4			—			—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.4			0.2			—			0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3			—			—			—



	Eversource		CL&P		NSTAR Electric		PSNH
For the Six Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	5.9	$	0.1	$	0.8	$	—
Operating Cash Flows from Finance Leases	0.6		0.3		0.3		—
Financing Cash Flows from Finance Leases	0.9		0.7		—		—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	1.7		0.2		—		0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3		—		—		—

Future minimum lease payments, excluding variable costs, under long-term leases, as of June 30, 2019 are as follows:



	Operating Leases								Finance Leases
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
July 1, 2019 through December 31, 2019	$	5.7	$	0.3	$	0.8	$	0.2	$	1.7	$	1.0	$	0.3	$	0.1
Year Ending December 31,
2020	10.3		0.2		1.6		0.2		3.4		2.0		0.5		0.1
2021	9.2		0.1		1.6		0.2		2.9		1.5		0.5		0.1
2022	7.5		—		1.6		0.1		1.5		—		0.6		0.1
2023	4.9		—		1.6		0.1		0.7		—		0.6		0.1
2024	2.9		—		1.7		—		0.7		—		0.6		0.1
Thereafter	29.2		0.1		28.9		0.2		13.2		—		12.8		0.4
Future lease payments	69.7		0.7		37.8		1.0		24.1		4.5		15.9		1.0
Less amount representing interest	15.1		0.1		13.4		0.2		12.5		0.7		11.5		0.1
Present value of future minimum lease payments	$	54.6	$	0.6	$	24.4	$	0.8	$	11.6	$	3.8	$	4.4	$	0.9

At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows:



Operating Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	11.5	$	1.5	$	7.2	$	0.5
2020	9.8		1.4		6.0		0.4
2021	8.7		1.2		5.3		0.4
2022	7.2		1.1		4.4		0.4
2023	4.7		0.5		3.1		0.2
Thereafter	32.7		0.2		29.5		0.3
Future minimum lease payments	$	74.6	$	5.9	$	55.5	$	2.2



Capital Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	3.4	$	2.0	$	0.5	$	0.1
2020	3.4		2.0		0.5		0.1
2021	2.9		1.5		0.5		0.1
2022	1.5		—		0.6		0.1
2023	0.7		—		0.6		0.1
Thereafter	13.9		—		13.4		0.5
Future minimum lease payments	25.8		5.5		16.1		1.0
Less amount representing interest	13.8		1.0		12.4		0.1
Present value of future minimum lease payments	$	12.0	$	4.5	$	3.7	$	0.9

LEASES

Eversource, including CL&P, NSTAR Electric and PSNH, has entered into lease agreements as a lessee for the use of land, office space, service centers, vehicles, information technology, and equipment. These lease agreements are classified as either finance or operating leases and the liability and right-of-use asset are recognized on the balance sheet at lease commencement. Leases with an initial term of 12 months or less are not recorded on the balance sheet and are recognized as lease expense on a straight-line basis over the lease term.

Eversource determines whether or not a contract contains a lease based on whether or not it provides Eversource with the use of a specifically identified asset for a period of time, as well as both the right to direct the use of that asset and receive the significant economic benefits of the asset. Eversource has elected the practical expedient to not separate non-lease components from lease components and instead to account for both as a single lease component, with the exception of the information technology asset class where the lease and non-lease components are separated.

The provisions of Eversource, CL&P, NSTAR Electric and PSNH lease agreements contain renewal options. The renewal options range from one year to twenty years. The renewal period is included in the measurement of the lease liability if it is reasonably certain that Eversource will exercise these renewal options.

For leases entered into or modified after the January 1, 2019 implementation date, the discount rate utilized for classification and measurement purposes as of the inception date of the lease is based on each company's collateralized incremental interest rate to borrow over a comparable term for an individual lease, as the rate implicit in the lease is not determinable.

CL&P and PSNH entered into certain contracts for the purchase of energy that qualify as leases. These contracts do not have minimum lease payments and therefore are not recognized as a lease liability on the balance sheet and are not reflected in the future minimum lease payments table below. Expense related to these contracts are included as variable lease cost in the table below. The expense and long-term obligation for these contracts are included in the annually reported contractual obligations table in Note 12B, "Commitments and Contingencies - Long-Term Contractual Arrangements," of the Eversource 2018 Form 10-K.

The components of lease cost, prior to amounts capitalized, are as follows:



	For the Three Months Ended June 30, 2019								For the Six Months Ended June 30, 2019
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Financing Lease Cost:
Amortization of Right-of-use-Assets	$	0.4	$	0.2	$	—	$	—	$	0.7	$	0.4	$	0.1	$	—
Interest on Lease Liabilities	0.3		0.1		0.2		—		0.7		0.3		0.3		—
Total Finance Lease Cost	0.7		0.3		0.2		—		1.4		0.7		0.4		—
Operating Lease Cost	2.9		0.1		0.5		—		5.9		0.1		0.9		—
Variable Lease Cost	15.7		3.1		—		12.6		31.1		6.5		—		24.6
Total Lease Cost	$	19.3	$	3.5	$	0.7	$	12.6	$	38.4	$	7.3	$	1.3	$	24.6

Operating lease cost, less the capitalized portion, is included in Operations and Maintenance (or Purchased Power, Fuel and Transmission expense for transmission segment leases) on the statements of income. Amortization of finance lease assets is included in Depreciation on the statements of income. Interest expense on finance leases is included in Interest Expense, Net on the statements of income.

Supplemental balance sheet information related to leases is as follows:



		As of June 30, 2019
(Millions of Dollars)	Balance Sheet Classification	Eversource		CL&P		NSTAR Electric		PSNH
Operating Leases:
Operating Lease Right-of-use-Assets, Net	Other Long-Term Assets	$	54.6	$	0.6	$	24.4	$	0.8
Operating Lease Liabilities
Operating Lease Liabilities - Current Portion	Other Current Liabilities	$	8.8	$	0.2	$	0.5	$	0.2
Operating Lease Liabilities - Long-Term	Other Long-Term Liabilities	45.8		0.4		23.9		0.6
Total Operating Lease Liabilities		$	54.6	$	0.6	$	24.4	$	0.8
Finance Leases:
Finance Lease Right-of-use-Assets, Net	Property, Plant and Equipment, Net	$	9.4	$	2.6	$	3.4	$	0.9
Finance Lease Liabilities
Finance Lease Liabilities - Current Portion	Other Current Liabilities	$	2.3	$	1.5	$	—	$	0.1
Finance Lease Liabilities - Long-Term	Other Long-Term Liabilities	9.3		2.3		4.4		0.8
Total Finance Lease Liabilities		$	11.6	$	3.8	$	4.4	$	0.9

The finance lease payments that NSTAR Electric will make over the next twelve months are entirely interest-related, due to escalating payments. As such, none of the finance lease payments over the next twelve months will reduce the finance lease liability.

Other information related to leases is as follows (in millions of dollars, unless otherwise noted):



	Eversource			CL&P			NSTAR Electric			PSNH
As of June 30, 2019
Weighted-Average Remaining Lease Term (Years):
Operating Leases	12			4			21			8
Financing Leases	11			2			23			9
Weighted-Average Discount Rate (Percentage):
Operating Leases	3.9		%	2.7		%	4.1		%	3.6		%
Financing Leases	4.3		%	10.5		%	2.9		%	3.5		%

For the Three Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	3.0		$	0.1		$	0.5		$	—
Operating Cash Flows from Finance Leases	0.3			0.1			0.1			—
Financing Cash Flows from Finance Leases	0.5			0.4			—			—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.4			0.2			—			0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3			—			—			—



	Eversource		CL&P		NSTAR Electric		PSNH
For the Six Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	5.9	$	0.1	$	0.8	$	—
Operating Cash Flows from Finance Leases	0.6		0.3		0.3		—
Financing Cash Flows from Finance Leases	0.9		0.7		—		—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	1.7		0.2		—		0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3		—		—		—

Future minimum lease payments, excluding variable costs, under long-term leases, as of June 30, 2019 are as follows:



	Operating Leases								Finance Leases
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
July 1, 2019 through December 31, 2019	$	5.7	$	0.3	$	0.8	$	0.2	$	1.7	$	1.0	$	0.3	$	0.1
Year Ending December 31,
2020	10.3		0.2		1.6		0.2		3.4		2.0		0.5		0.1
2021	9.2		0.1		1.6		0.2		2.9		1.5		0.5		0.1
2022	7.5		—		1.6		0.1		1.5		—		0.6		0.1
2023	4.9		—		1.6		0.1		0.7		—		0.6		0.1
2024	2.9		—		1.7		—		0.7		—		0.6		0.1
Thereafter	29.2		0.1		28.9		0.2		13.2		—		12.8		0.4
Future lease payments	69.7		0.7		37.8		1.0		24.1		4.5		15.9		1.0
Less amount representing interest	15.1		0.1		13.4		0.2		12.5		0.7		11.5		0.1
Present value of future minimum lease payments	$	54.6	$	0.6	$	24.4	$	0.8	$	11.6	$	3.8	$	4.4	$	0.9

At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows:



Operating Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	11.5	$	1.5	$	7.2	$	0.5
2020	9.8		1.4		6.0		0.4
2021	8.7		1.2		5.3		0.4
2022	7.2		1.1		4.4		0.4
2023	4.7		0.5		3.1		0.2
Thereafter	32.7		0.2		29.5		0.3
Future minimum lease payments	$	74.6	$	5.9	$	55.5	$	2.2



Capital Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	3.4	$	2.0	$	0.5	$	0.1
2020	3.4		2.0		0.5		0.1
2021	2.9		1.5		0.5		0.1
2022	1.5		—		0.6		0.1
2023	0.7		—		0.6		0.1
Thereafter	13.9		—		13.4		0.5
Future minimum lease payments	25.8		5.5		16.1		1.0
Less amount representing interest	13.8		1.0		12.4		0.1
Present value of future minimum lease payments	$	12.0	$	4.5	$	3.7	$	0.9

FAIR VALUE OF FINANCIAL INSTRUMENTS

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

FAIR VALUE OF FINANCIAL INSTRUMENTS

The following methods and assumptions were used to estimate the fair value of each of the following financial instruments:

Preferred Stock, Long-Term Debt and Rate Reduction Bonds: The fair value of CL&P's and NSTAR Electric's preferred stock is based upon pricing models that incorporate interest rates and other market factors, valuations or trades of similar securities and cash flow projections. The fair value of long-term debt and RRB debt securities is based upon pricing models that incorporate quoted market prices for those issues or similar issues adjusted for market conditions, credit ratings of the respective companies and treasury benchmark yields. The fair values provided in the table below are classified as Level 2 within the fair value hierarchy. Carrying amounts and estimated fair values are as follows:



	Eversource				CL&P				NSTAR Electric				PSNH
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
As of June 30, 2019:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	161.0	$	116.2	$	117.4	$	43.0	$	43.6	$	—	$	—
Long-Term Debt	13,818.5		14,639.4		3,309.5		3,724.9		3,341.5		3,599.6		1,101.8		1,145.3
Rate Reduction Bonds	604.9		642.2		—		—		—		—		604.9		642.2

As of December 31, 2018:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	156.8	$	116.2	$	113.8	$	43.0	$	43.0	$	—	$	—
Long-Term Debt	13,086.1		13,154.9		3,254.0		3,429.2		2,944.8		3,024.1		805.2		819.5
Rate Reduction Bonds	635.7		645.8		—		—		—		—		635.7		645.8

Derivative Instruments and Marketable Securities: Derivative instruments and investments in marketable securities are carried at fair value. For further information, see Note 4, "Derivative Instruments," and Note 5, "Marketable Securities," to the financial statements.

See Note 1E, "Summary of Significant Accounting Policies - Fair Value Measurements," for the fair value measurement policy and the fair value hierarchy.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)

The changes in accumulated other comprehensive income/(loss) by component, net of tax, are as follows:



	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Qualified Cash Flow Hedging Instruments			Unrealized Gains/(Losses) on Marketable Securities			Defined Benefit Plans			Total			Qualified Cash Flow Hedging Instruments			Unrealized Losses on Marketable Securities			Defined Benefit Plans			Total
Balance as of January 1st	$	(4.4	)	$	(0.5	)	$	(55.1	)	$	(60.0	)	$	(6.2	)	$	—		$	(60.2	)	$	(66.4	)

OCI Before Reclassifications	—			1.1			2.6			3.7			—			(0.6		)	2.6			2.0
Amounts Reclassified from AOCI	0.6			—			2.1			2.7			1.2			—			2.2			3.4
Net OCI	0.6			1.1			4.7			6.4			1.2			(0.6		)	4.8			5.4
Balance as of June 30th	$	(3.8	)	$	0.6		$	(50.4	)	$	(53.6	)	$	(5.0	)	$	(0.6	)	$	(55.4	)	$	(61.0	)

Eversource's qualified cash flow hedging instruments represent interest rate swap agreements on debt issuances that were settled in prior years. The settlement amount was recorded in AOCI and is being amortized into Net Income over the term of the underlying debt instrument. CL&P, NSTAR Electric and PSNH continue to amortize interest rate swaps settled in prior years from AOCI into Interest Expense over the remaining life of the associated long-term debt. Such interest rate swaps are not material to their respective financial statements.

Defined benefit plan OCI amounts before reclassifications relate to actuarial gains and losses that arose during the year and were recognized in AOCI. The unamortized actuarial gains and losses and prior service costs on the defined benefit plans are amortized from AOCI into Other Income, Net over the average future employee service period, and are reflected in amounts reclassified from AOCI.

Eversource did not elect to reclassify the income tax effects of the Tax Cuts and Jobs Act from AOCI to Retained Earnings as permitted by ASU 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220).

COMMON SHARES

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

COMMON SHARES

The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric and PSNH that were authorized and issued, as well as the respective per share par values:



	Shares
			Authorized as of June 30, 2019 and December 31, 2018	Issued as of
	Par Value		Authorized as of June 30, 2019 and December 31, 2018	June 30, 2019	December 31, 2018
Eversource	$	5	380,000,000	339,858,402	333,878,402
CL&P	$	10	24,500,000	6,035,205	6,035,205
NSTAR Electric	$	1	100,000,000	200	200
PSNH	$	1	100,000,000	301	301

Common Share Issuance and Forward Sale Agreement: On June 4, 2019, Eversource completed an equity offering of 17,940,000 common shares, consisting of 5,980,000 common shares issued directly by the Company and 11,960,000 common shares issuable pursuant to a forward sale agreement with an investment bank. The issuance of 5,980,000 common shares resulted in proceeds of $426.9 million, net of issuance costs, and was reflected in shareholders’ equity and as a financing activity on the statement of cash flows.

Under the forward sale agreement, a total of 11,960,000 common shares were borrowed from third parties and sold to the underwriters. The forward sale agreement allows Eversource, at its election and prior to May 29, 2020, to physically settle the forward sale agreement by issuing common shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreement (initially, $71.48 per share) or, alternatively, to settle the forward sale agreement in whole or in part through the delivery or receipt of shares or cash. The forward sale price is subject to adjustment daily based on a floating interest rate factor and will decrease in respect of certain fixed amounts specified in the agreement, such as dividends.

Eversource’s intent is to physically settle the forward sale agreement by issuing common shares. As of June 30, 2019, if Eversource had elected to net settle the forward sale agreement, Eversource would have been required to pay $50.2 million under a cash settlement or would have been required to deliver 662,694 common shares under a net share settlement.

Issuances of shares under the forward sale agreement are classified as equity transactions. Accordingly, no amounts relating to the forward sale agreement have or will be recorded in the financial statements until settlements take place. Prior to any settlements, the only impact to the financial statements is the inclusion of incremental shares within the calculation of diluted EPS using the treasury stock method. See Note 15, "Earnings Per Share," for information on the forward sale agreement’s impact on the calculation of diluted EPS.

Treasury Shares: As of June 30, 2019 and December 31, 2018, there were 16,283,963 and 16,992,594 Eversource common shares held as treasury shares, respectively. As of June 30, 2019 and December 31, 2018, Eversource common shares outstanding were 323,574,439 and 316,885,808, respectively.

Beginning in 2019, Eversource began issuing treasury shares to satisfy awards under the Company's incentive plans, shares issued under the dividend reinvestment plan, and matching contributions under the Eversource 401k Plan.

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS

Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended June 30, 2019 and 2018 and $3.8 million for each of the six months ended June 30, 2019 and 2018. These dividends were presented as Net Income Attributable to Noncontrolling Interests on the Eversource statements of income. Noncontrolling Interest – Preferred Stock of Subsidiaries on the Eversource balance sheets totaled $155.6 million as of June 30, 2019 and December 31, 2018. On the Eversource balance sheets, Common Shareholders' Equity was fully attributable to Eversource parent and Noncontrolling Interest – Preferred Stock of Subsidiaries was fully attributable to the noncontrolling interest.

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS

COMMON SHARES

The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric and PSNH that were authorized and issued, as well as the respective per share par values:



	Shares
			Authorized as of June 30, 2019 and December 31, 2018	Issued as of
	Par Value		Authorized as of June 30, 2019 and December 31, 2018	June 30, 2019	December 31, 2018
Eversource	$	5	380,000,000	339,858,402	333,878,402
CL&P	$	10	24,500,000	6,035,205	6,035,205
NSTAR Electric	$	1	100,000,000	200	200
PSNH	$	1	100,000,000	301	301

Common Share Issuance and Forward Sale Agreement: On June 4, 2019, Eversource completed an equity offering of 17,940,000 common shares, consisting of 5,980,000 common shares issued directly by the Company and 11,960,000 common shares issuable pursuant to a forward sale agreement with an investment bank. The issuance of 5,980,000 common shares resulted in proceeds of $426.9 million, net of issuance costs, and was reflected in shareholders’ equity and as a financing activity on the statement of cash flows.

Under the forward sale agreement, a total of 11,960,000 common shares were borrowed from third parties and sold to the underwriters. The forward sale agreement allows Eversource, at its election and prior to May 29, 2020, to physically settle the forward sale agreement by issuing common shares in exchange for net proceeds at the then-applicable forward sale price specified by the agreement (initially, $71.48 per share) or, alternatively, to settle the forward sale agreement in whole or in part through the delivery or receipt of shares or cash. The forward sale price is subject to adjustment daily based on a floating interest rate factor and will decrease in respect of certain fixed amounts specified in the agreement, such as dividends.

Eversource’s intent is to physically settle the forward sale agreement by issuing common shares. As of June 30, 2019, if Eversource had elected to net settle the forward sale agreement, Eversource would have been required to pay $50.2 million under a cash settlement or would have been required to deliver 662,694 common shares under a net share settlement.

Issuances of shares under the forward sale agreement are classified as equity transactions. Accordingly, no amounts relating to the forward sale agreement have or will be recorded in the financial statements until settlements take place. Prior to any settlements, the only impact to the financial statements is the inclusion of incremental shares within the calculation of diluted EPS using the treasury stock method. See Note 15, "Earnings Per Share," for information on the forward sale agreement’s impact on the calculation of diluted EPS.

Treasury Shares: As of June 30, 2019 and December 31, 2018, there were 16,283,963 and 16,992,594 Eversource common shares held as treasury shares, respectively. As of June 30, 2019 and December 31, 2018, Eversource common shares outstanding were 323,574,439 and 316,885,808, respectively.

Beginning in 2019, Eversource began issuing treasury shares to satisfy awards under the Company's incentive plans, shares issued under the dividend reinvestment plan, and matching contributions under the Eversource 401k Plan.

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS

Dividends on the preferred stock of CL&P and NSTAR Electric totaled $1.9 million for each of the three months ended June 30, 2019 and 2018 and $3.8 million for each of the six months ended June 30, 2019 and 2018. These dividends were presented as Net Income Attributable to Noncontrolling Interests on the Eversource statements of income. Noncontrolling Interest – Preferred Stock of Subsidiaries on the Eversource balance sheets totaled $155.6 million as of June 30, 2019 and December 31, 2018. On the Eversource balance sheets, Common Shareholders' Equity was fully attributable to Eversource parent and Noncontrolling Interest – Preferred Stock of Subsidiaries was fully attributable to the noncontrolling interest.

EARNINGS PER SHARE

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

EARNINGS PER SHARE

Basic EPS is computed based upon the weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied.

As described in Note 13, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement will be determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market price during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price.

The following table sets forth the components of basic and diluted EPS:



Eversource (Millions of Dollars, except share information)	For the Three Months Ended				For the Six Months Ended
Eversource (Millions of Dollars, except share information)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Net Income Attributable to Common Shareholders	$	31.5	$	242.8	$	340.1	$	512.3
Weighted Average Common Shares Outstanding:
Basic	319,664,998		317,344,596		318,644,796		317,370,825
Dilutive Effect of:
Share-Based Compensation Awards and Other	645,450		540,591		668,470		568,269
Equity Forward Sale Agreement	78,042		—		39,021		—
Total Dilutive Effect	723,492		540,591		707,491		568,269
Diluted	320,388,490		317,885,187		319,352,287		317,939,094
Basic and Diluted EPS	$	0.10	$	0.76	$	1.07	$	1.61

REVENUES

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

REVENUES

The following tables present operating revenues disaggregated by revenue source:



	For the Three Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission		Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	805.0		$	100.2		$	—	$	33.6		$	—	$	—		$	938.8
Commercial	612.8			69.5			—		16.0			—		(0.9		)	697.4
Industrial	81.3			23.5			—		1.1			—		(2.8		)	103.1
Total Retail Tariff Sales Revenues	1,499.1			193.2			—		50.7			—		(3.7		)	1,739.3
Wholesale Transmission Revenues	—			—			281.2		—			14.7		(239.8		)	56.1
Wholesale Market Sales Revenues	39.4			14.4			—		0.9			—		—			54.7
Other Revenues from Contracts with Customers	15.1			0.4			3.7		1.8			236.1		(236.8		)	20.3
Reserve for Revenues Subject to Refund	(3.1		)	1.5			—		(0.6		)	—		—			(2.2		)
Total Revenues from Contracts with Customers	1,550.5			209.5			284.9		52.8			250.8		(480.3		)	1,868.2
Alternative Revenue Programs	6.3			(2.7		)	64.6		0.7			—		(58.8		)	10.1
Other Revenues ⁽¹⁾	5.0			0.9			0.1		0.2			—		—			6.2
Total Operating Revenues	$	1,561.8		$	207.7		$	349.6	$	53.7		$	250.8	$	(539.1	)	$	1,884.5


	For the Six Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission		Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	1,838.3		$	359.1		$	—	$	60.5		$	—	$	—		$	2,257.9
Commercial	1,265.3			213.3			—		30.3			—		(2.0		)	1,506.9
Industrial	163.4			54.4			—		2.2			—		(5.5		)	214.5
Total Retail Tariff Sales Revenues	3,267.0			626.8			—		93.0			—		(7.5		)	3,979.3
Wholesale Transmission Revenues	—			—			606.1		—			28.3		(510.7		)	123.7
Wholesale Market Sales Revenues	90.8			36.1			—		1.9			—		—			128.8
Other Revenues from Contracts with Customers	27.7			1.4			6.9		3.5			480.7		(482.2		)	38.0
Reserve for Revenues Subject to Refund	(6.1		)	3.1			—		(1.2		)	—		—			(4.2		)
Total Revenues from Contracts with Customers	3,379.4			667.4			613.0		97.2			509.0		(1,000.4		)	4,265.6
Alternative Revenue Programs	8.4			7.7			77.0		1.5			—		(69.8		)	24.8
Other Revenues ⁽¹⁾	7.8			1.5			0.1		0.5			—		—			9.9
Total Operating Revenues	$	3,395.6		$	676.6		$	690.1	$	99.2		$	509.0	$	(1,070.2	)	$	4,300.3



	For the Three Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	794.4		$	104.1		$	—		$	32.3		$	—	$	—		$	930.8
Commercial	622.0			70.0			—			15.7			—		(2.0		)	705.7
Industrial	88.4			23.5			—			1.1			—		(2.4		)	110.6
Total Retail Tariff Sales Revenues	1,504.8			197.6			—			49.1			—		(4.4		)	1,747.1
Wholesale Transmission Revenues	—			—			310.8			—			12.6		(268.0		)	55.4
Wholesale Market Sales Revenues	34.2			12.1			—			0.9			—		—			47.2
Other Revenues from Contracts with Customers	18.4			(0.6		)	3.2			1.9			224.4		(225.1		)	22.2
Reserve for Revenues Subject to Refund	(7.3		)	(3.5		)	—			(0.5		)	—		—			(11.3		)
Total Revenues from Contracts with Customers	1,550.1			205.6			314.0			51.4			237.0		(497.5		)	1,860.6
Alternative Revenue Programs	(14.4		)	0.1			3.4			1.9			—		(2.9		)	(11.9		)
Other Revenues	4.2			0.8			—			0.2			—		—			5.2
Total Operating Revenues	$	1,539.9		$	206.5		$	317.4		$	53.5		$	237.0	$	(500.4	)	$	1,853.9


	For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	1,788.7		$	352.9		$	—		$	59.7		$	—	$	—		$	2,201.3
Commercial	1,233.4			204.7			—			30.0			—		(2.1		)	1,466.0
Industrial	169.9			53.1			—			2.1			—		(5.0		)	220.1
Total Retail Tariff Sales Revenues	3,192.0			610.7			—			91.8			—		(7.1		)	3,887.4
Wholesale Transmission Revenues	—			—			624.5			—			22.7		(526.7		)	120.5
Wholesale Market Sales Revenues	92.7			29.9			—			1.7			—		—			124.3
Other Revenues from Contracts with Customers	35.3			(0.9		)	6.2			3.7			445.2		(446.3		)	43.2
Reserve for Revenues Subject to Refund	(26.5		)	(8.0		)	—			(2.0		)	—		—			(36.5		)
Total Revenues from Contracts with Customers	3,293.5			631.7			630.7			95.2			467.9		(980.1		)	4,138.9
Alternative Revenue Programs	(5.7		)	(1.7		)	(8.3		)	2.6			—		7.7			(5.4		)
Other Revenues	6.7			1.4			—			0.2			—		—			8.3
Total Operating Revenues	$	3,294.5		$	631.4		$	622.4		$	98.0		$	467.9	$	(972.4	)	$	4,141.8



	For the Three Months Ended June 30, 2019									For the Three Months Ended June 30, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	402.8		$	282.3		$	119.9		$	387.1		$	292.5		$	114.8
Commercial	224.7			315.8			72.7			220.7			325.5			76.2
Industrial	33.8			28.9			18.6			36.5			30.9			21.0
Total Retail Tariff Sales Revenues	661.3			627.0			211.2			644.3			648.9			212.0
Wholesale Transmission Revenues	115.9			127.5			37.8			139.9			120.9			50.1
Wholesale Market Sales Revenues	12.1			17.2			10.1			10.6			13.4			10.9
Other Revenues from Contracts with Customers	9.1			6.1			4.2			8.3			9.3			3.9
Reserve for Revenues Subject to Refund	—			—			(3.1		)	(4.2		)	—			(3.1		)
Total Revenues from Contracts with Customers	798.4			777.8			260.2			798.9			792.5			273.8
Alternative Revenue Programs	55.1			2.1			13.7			1.0			(6.9		)	(5.0		)
Other Revenues ⁽¹⁾	2.7			1.9			0.5			2.4			1.6			0.2
Eliminations	(115.4		)	(99.9		)	(33.5		)	(107.4		)	(96.5		)	(33.9		)
Total Operating Revenues	$	740.8		$	681.9		$	240.9		$	694.9		$	690.7		$	235.1

	For the Six Months Ended June 30, 2019									For the Six Months Ended June 30, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	913.4		$	653.2		$	271.7		$	870.4		$	656.7		$	261.6
Commercial	461.3			652.3			152.6			443.2			640.0			151.1
Industrial	68.4			57.8			37.2			72.3			59.0			38.6
Total Retail Tariff Sales Revenues	1,443.1			1,363.3			461.5			1,385.9			1,355.7			451.3
Wholesale Transmission Revenues	270.7			250.1			85.3			290.6			239.5			94.3
Wholesale Market Sales Revenues	25.8			41.6			23.4			21.0			38.2			34.9
Other Revenues from Contracts with Customers	18.0			10.1			7.8			16.2			18.3			7.5
Reserve for Revenues Subject to Refund	—			—			(6.1		)	(16.6		)	(3.7		)	(6.2		)
Total Revenues from Contracts with Customers	1,757.6			1,665.1			571.9			1,697.1			1,648.0			581.8
Alternative Revenue Programs	60.9			9.3			15.2			(4.1		)	(0.2		)	(9.6		)
Other Revenues ⁽¹⁾	3.7			3.4			0.8			3.3			2.7			0.6
Eliminations	(232.1		)	(198.3		)	(70.6		)	(216.4		)	(189.6		)	(70.3		)
Total Operating Revenues	$	1,590.1		$	1,479.5		$	517.3		$	1,479.9		$	1,460.9		$	502.5

⁽¹⁾

Other Revenues include certain fees charged to customers, which are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.1 million at Eversource, $0.3 million at CL&P, and $0.7 million at NSTAR Electric for the three months ended June 30, 2019, and $2.2 million at Eversource, $0.5 million at CL&P, and $1.3 million at NSTAR Electric for the six months ended June 30, 2019, respectively.

SEGMENT INFORMATION

6 Months Ended

Jun. 30, 2019

Segment Reporting [Abstract]

SEGMENT INFORMATION

Eversource is organized into the Electric Distribution, Electric Transmission, Natural Gas Distribution and Water Distribution reportable segments and Other based on a combination of factors, including the characteristics of each segments' services, the sources of operating revenues and expenses and the regulatory environment in which each segment operates. These reportable segments represent substantially all of Eversource's total consolidated revenues. Revenues from the sale of electricity, natural gas and water primarily are derived from residential, commercial and industrial customers and are not dependent on any single customer. The Electric Distribution reportable segment includes the results of PSNH's generation facilities prior to sales in January and August 2018, and NSTAR Electric's solar power facilities. Eversource's reportable segments are determined based upon the level at which Eversource's chief operating decision maker assesses performance and makes decisions about the allocation of company resources.

The remainder of Eversource's operations is presented as Other in the tables below and primarily consists of 1) the equity in earnings of Eversource parent from its subsidiaries and intercompany interest income, both of which are eliminated in consolidation, and interest expense related to the debt of Eversource parent, 2) the revenues and expenses of Eversource Service, most of which are eliminated in consolidation, 3) the operations of CYAPC and YAEC, 4) Eversource Water Ventures, Inc., parent company of Aquarion, and 5) the results of other unregulated subsidiaries, which are not part of its core business. In addition, Other in the tables below includes Eversource parent's equity ownership interests that are not consolidated, which include a natural gas pipeline project owned by Enbridge, Inc., the offshore wind business, a renewable energy investment fund, and two companies that transmit hydroelectricity imported from the Hydro-Quebec system in Canada. In the ordinary course of business, Yankee Gas and NSTAR Gas purchase natural gas transmission services from the Enbridge, Inc. natural gas pipeline project described above. These affiliate transaction costs total approximately $62.5 million annually and are classified as Purchased Power, Fuel and Transmission on the Eversource statements of income.

Each of Eversource's subsidiaries, including CL&P, NSTAR Electric and PSNH, has one reportable segment.

Cash flows used for investments in plant included in the segment information below are cash capital expenditures that do not include amounts incurred but not paid, cost of removal, AFUDC related to equity funds, and the capitalized portions of pension and PBOP expense.

Eversource's segment information is as follows:



	For the Three Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	1,561.8		$	207.7		$	349.6		$	53.7		$	250.8		$	(539.1	)	$	1,884.5
Depreciation and Amortization	(150.1		)	(19.5		)	(62.3		)	(12.0		)	(14.7		)	0.6			(258.0		)
Impairment of Northern Pass Transmission	—			—			(239.6		)	—			—			—			(239.6		)
Other Operating Expenses	(1,243.0		)	(179.8		)	(108.4		)	(25.0		)	(218.4		)	538.7			(1,235.9		)
Operating Income/(Loss)	$	168.7		$	8.4		$	(60.7	)	$	16.7		$	17.7		$	0.2		$	151.0
Interest Expense	$	(50.8	)	$	(11.9	)	$	(30.5	)	$	(8.6	)	$	(44.5	)	$	13.6		$	(132.7	)
Other Income/(Loss), Net	12.2			0.7			8.7			0.1			(114.9		)	139.1			45.9
Net Income/(Loss) Attributable to Common Shareholders	105.4			(1.8		)	(87.4		)	8.0			(145.6		)	152.9			31.5


	For the Six Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	3,395.6		$	676.6		$	690.1		$	99.2		$	509.0		$	(1,070.2	)	$	4,300.3
Depreciation and Amortization	(329.3		)	(39.9		)	(123.7		)	(23.9		)	(28.3		)	1.1			(544.0		)
Impairment of Northern Pass Transmission	—			—			(239.6		)	—			—			—			(239.6		)
Other Operating Expenses	(2,718.6		)	(521.1		)	(207.2		)	(49.9		)	(444.0		)	1,069.8			(2,871.0		)
Operating Income	$	347.7		$	115.6		$	119.6		$	25.4		$	36.7		$	0.7		$	645.7
Interest Expense	$	(100.0	)	$	(23.7	)	$	(61.0	)	$	(17.2	)	$	(88.6	)	$	26.1		$	(264.4	)
Other Income, Net	30.4			1.0			16.8			0.4			316.8			(288.5		)	76.9
Net Income Attributable to Common Shareholders	225.4			74.7			30.9			8.8			262.0			(261.7		)	340.1
Cash Flows Used for Investments in Plant	571.3			202.7			449.2			51.4			103.2			—			1,377.8



	For the Three Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	1,539.9		$	206.5		$	317.4		$	53.5		$	237.0		$	(500.4	)	$	1,853.9
Depreciation and Amortization	(135.5		)	(19.3		)	(57.0		)	(12.2		)	(11.9		)	0.6			(235.3		)
Other Operating Expenses	(1,233.0		)	(170.6		)	(88.8		)	(24.5		)	(211.7		)	501.4			(1,227.2		)
Operating Income	$	171.4		$	16.6		$	171.6		$	16.8		$	13.4		$	1.6		$	391.4
Interest Expense	$	(52.1	)	$	(11.4	)	$	(30.0	)	$	(8.6	)	$	(32.3	)	$	8.0		$	(126.4	)
Other Income/(Loss), Net	19.0			1.6			9.9			(0.6		)	302.0			(281.8		)	50.1
Net Income Attributable to Common Shareholders	101.3			5.0			112.7			7.2			288.8			(272.2		)	242.8

	For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	3,294.5		$	631.4		$	622.4		$	98.0		$	467.9		$	(972.4	)	$	4,141.8
Depreciation and Amortization	(279.9		)	(45.7		)	(113.5		)	(22.9		)	(23.9		)	1.1			(484.8		)
Other Operating Expenses	(2,676.5		)	(483.2		)	(172.0		)	(48.4		)	(416.3		)	973.3			(2,823.1		)
Operating Income	$	338.1		$	102.5		$	336.9		$	26.7		$	27.7		$	2.0		$	833.9
Interest Expense	$	(99.5	)	$	(22.5	)	$	(59.7	)	$	(16.9	)	$	(64.3	)	$	15.4		$	(247.5	)
Other Income/(Loss), Net	38.6			3.5			17.8			(1.1		)	662.1			(637.0		)	83.9
Net Income Attributable to Common Shareholders	205.5			62.8			220.1			8.7			634.8			(619.6		)	512.3
Cash Flows Used for Investments in Plant	475.6			150.3			508.5			40.2			77.1			—			1,251.7

The following table summarizes Eversource's segmented total assets:



Eversource (Millions of Dollars)	Electric Distribution		Natural Gas Distribution		Electric Transmission		Water Distribution		Other		Eliminations			Total
As of June 30, 2019	$	21,628.8	$	4,031.3	$	10,499.7	$	2,290.5	$	18,550.4	$	(18,004.8	)	$	38,995.9
As of December 31, 2018	21,389.1		3,904.9		10,285.0		2,253.0		17,874.2		(17,464.9		)	38,241.3

For further information regarding the 2019 impairment of NPT, see Note 1C, "Summary of Significant Accounting Policies - Impairment of Northern Pass Transmission," to the financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Eversource Energy is a public utility holding company primarily engaged, through its wholly-owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy's wholly-owned regulated utility subsidiaries consist of CL&P, NSTAR Electric and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight regulated utilities in Connecticut, Massachusetts and New Hampshire. The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P are herein collectively referred to as the "financial statements." The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, "Financial Statements and Supplementary Data," of the Eversource 2018 Form 10-K, which was filed with the SEC on February 26, 2019. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource's, CL&P's, NSTAR Electric's and PSNH's financial position as of June 30, 2019 and December 31, 2018, and the results of operations, comprehensive income and common shareholders' equity for the three and six months ended June 30, 2019 and 2018, and the cash flows for the six months ended June 30, 2019 and 2018. The results of operations and comprehensive income for the three and six months ended June 30, 2019 and 2018 and the cash flows for the six months ended June 30, 2019 and 2018 are not necessarily indicative of the results expected for a full year. Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Eversource's utility subsidiaries' electric, natural gas and water distribution and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, "Regulatory Accounting," for further information. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation.
Accounting Standards	Accounting Standards Accounting Standards Issued but Not Yet Effective: In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a new model for recognizing credit losses on financial instruments based on an estimate of current expected credit losses. Under the new guidance, immediate recognition of all credit losses expected over the life of a financial instrument is required. The new standard also revises the other-than-temporary impairment model for available-for-sale debt securities. The standard is effective January 1, 2020, and requires a modified retrospective transition approach through a cumulative-effect adjustment to retained earnings. The Company is assessing the impacts of this standard on the accounting for credit losses on its financial instruments, including accounts receivable. Accounting Standards Recently Adopted: On January 1, 2019, the Company adopted ASU 2016-02, Leases (Topic 842), which amended existing lease accounting guidance. The Company applied the Topic 842 lease criteria to new leases and lease renewals entered into effective on or after January 1, 2019. The ASU required balance sheet recognition of leases deemed to be operating leases as well as additional disclosure requirements. The recognition, measurement and presentation of expenses and cash flows were not significantly changed. The Company also adopted the modified retrospective transition method allowed in ASU 2018-11, Leases (Topic 842) - Targeted Improvements, which allowed the Company to adopt the new leases standard as of January 1, 2019, with prior periods presented in the financial statements continuing to follow existing lease accounting guidance under Topic 840 (Leases) in the accounting literature. Implementation of ASU 2018-11 had no effect on retained earnings, and the requirements of the new lease standard (Topic 842) are reflected in the 2019 financial statements and footnotes. The Company elected the practical expedient package whereby it did not need to reassess whether or not an existing contract is or contains a lease or whether a lease is an operating or capital lease, and it did not need to reassess initial direct costs for leases. Election of this practical expedient allowed us to carry forward our historical lease classifications. The Company elected the practical expedient to not reevaluate land easements existing at adoption if they were not previously accounted for as leases. The Company also elected to use the discount rate as of the January 1, 2019 implementation date to discount its operating lease liabilities. The Company did not elect the hindsight practical expedient to determine the lease term for existing leases. The Company determined the impact the ASUs had on its financial statements by reviewing its lease population and identifying lease data needed for the disclosure requirements. The Company implemented a new lease accounting system in 2019 to ensure ongoing compliance with the ASU’s requirements. Adoption of the new standard resulted in the recording of operating lease liabilities and right-of-use assets on the balance sheet upon transition at January 1, 2019 of $58.0 million at Eversource, $25.3 million at NSTAR Electric, $0.6 million at CL&P, and $0.6 million at PSNH. Implementation of the new guidance did not have an impact on each company’s results of operations or cash flows.
Provision for Uncollectible Accounts	Provision for Uncollectible Accounts Eversource, including CL&P, NSTAR Electric and PSNH, presents its receivables at estimated net realizable value by maintaining a provision for uncollectible accounts. This provision is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. The estimate is based upon historical collection and write-off experience and management's assessment of collectability from customers. Management continuously assesses the collectability of receivables and adjusts collectability estimates based on actual experience. Receivable balances are written off against the provision for uncollectible accounts when the customer accounts are terminated and these balances are deemed to be uncollectible. The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows NSTAR Electric and NSTAR Gas to recover in rates amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets.
Fair Value Measurements	Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" ("normal") and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill and AROs, and the estimated fair value of preferred stock, long-term debt and RRBs. Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis, and Eversource's policy is to recognize transfers between levels of the fair value hierarchy as of the end of the reporting period. The three levels of the fair value hierarchy are described below: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable. Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products. Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy.
Other Taxes	As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income. Separate from above are amounts recorded as Taxes Other than Income Taxes related to the future remittance to the State of Connecticut of energy efficiency funds collected from customers in Operating Revenues. These amounts are $10.7 million and $21.4 million for the three and six months ended June 30, 2019, respectively, and $12.7 million and $25.4 million for the three and six months ended June 30, 2018, respectively. These amounts are recorded separately, with collections in Operating Revenues and with payments in Taxes Other than Income Taxes on the Eversource and CL&P statements of income. Other TaxesEversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers.
Restricted Cash	Restricted cash included in Prepayments and Other Current Assets primarily represents cash collections related to the PSNH RRB customer charges that are held in trust, and required ISO-NE cash deposits. Restricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage facilities obligations.
Earnings Per Share	Basic EPS is computed based upon the weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied. As described in Note 13, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement will be determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market price during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price.

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

+ References

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-Name Accounting Standards Codification
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

6 Months Ended

Jun. 30, 2019

Accounting Policies [Abstract]

Provision for Uncollectible Accounts

The provision balances are as follows:



	Total Provision for Uncollectible Accounts				Provision for Uncollectible Hardship Accounts
(Millions of Dollars)	As of June 30, 2019		As of December 31, 2018		As of June 30, 2019		As of December 31, 2018
Eversource	$	226.4	$	212.7	$	137.9	$	131.5
CL&P	88.7		88.0		70.9		71.9
NSTAR Electric	81.8		74.5		47.7		42.5
PSNH	11.2		11.1		—		—

Uncollectible expense associated with customers' accounts receivable included in Operations and Maintenance expense on the statements of income is as follows:



	For the Three Months Ended				For the Six Months Ended
(Millions of Dollars)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Eversource	$	13.0	$	9.5	$	31.5	$	29.3
CL&P	3.5		3.8		7.6		7.7
NSTAR Electric	5.7		3.8		11.6		11.3
PSNH	1.4		1.5		3.1		3.2

Components of Other Income, Net

The components of Other Income, Net on the statements of income were as follows:



	For the Three Months Ended
	June 30, 2019												June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P		NSTAR Electric		PSNH
Pension, SERP and PBOP Non-Service Income/(Expense) Components	$	5.8		$	(0.9	)	$	5.4		$	1.5		$	14.6		$	2.4	$	9.5	$	2.1
AFUDC Equity	13.1			3.2			5.1			0.9			10.9			3.3		3.9		—
Equity in Earnings ⁽¹⁾	25.9			0.1			0.2			—			22.9			—		0.4		—
Investment Income/(Loss)	(0.6		)	(0.1		)	(0.3		)	(0.1		)	(0.3		)	0.4		0.3		—
Interest Income	1.3			0.5			0.2			0.7			1.9			1.0		0.2		1.3
Other	0.4			0.1			0.1			—			0.1			—		—		—
Total Other Income, Net	$	45.9		$	2.9		$	10.7		$	3.0		$	50.1		$	7.1	$	14.3	$	3.4


	For the Six Months Ended
	June 30, 2019												June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P		NSTAR Electric		PSNH
Pension, SERP and PBOP Non-Service Income/(Expense) Components	$	13.1		$	(1.6	)	$	12.4		$	2.0		$	29.8		$	5.3	$	17.9	$	4.4
AFUDC Equity	24.1			5.8			9.1			1.1			20.6			6.1		7.3		—
Equity in Earnings ⁽¹⁾	30.9			0.1			0.4			—			27.5			—		0.4		—
Investment Income/(Loss)	0.6			1.7			(0.6		)	0.2			0.4			0.2		0.9		0.1
Interest Income ⁽²⁾	7.8			0.8			0.4			6.6			5.4			2.0		0.4		3.7
Other	0.4			(0.1		)	—			0.1			0.2			—		—		—
Total Other Income, Net	$	76.9		$	6.7		$	21.7		$	10.0		$	83.9		$	13.6	$	26.9	$	8.2

⁽¹⁾Equity in earnings includes $20.4 million of unrealized gains associated with an investment in a renewable energy fund for both the three and six months ended June 30, 2019. For both the three and six months ended June 30, 2018, unrealized gains on this investment totaled $17.6 million.

⁽²⁾See Note 2, "Regulatory Accounting" for interest income recognized in 2019 for the equity return component of carrying charges on storm costs at PSNH.

Other Taxes

These gross receipts taxes are recorded separately with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the statements of income as follows:



	For the Three Months Ended				For the Six Months Ended
(Millions of Dollars)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Eversource	$	36.4	$	35.6	$	81.4	$	79.0
CL&P	31.8		31.5		68.0		67.1

Non-cash Investing Activities

Non-cash investing activities include plant additions included in Accounts Payable as follows:



(Millions of Dollars)	As of June 30, 2019		As of June 30, 2018
Eversource	$	323.7	$	305.7
CL&P	114.0		110.9
NSTAR Electric	85.2		71.1
PSNH	29.9		46.6

Reconciliation of Cash Balances to Cash and Restricted Cash

The following table reconciles cash as reported on the balance sheets to the cash and restricted cash balance as reported on the statements of cash flows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Cash as reported on the Balance Sheets	$	20.6	$	2.2	$	0.2	$	0.3	$	108.1	$	87.7	$	1.6	$	1.4
Restricted cash included in:
Prepayments and Other Current Assets	54.1		4.6		6.1		35.0		72.1		3.5		13.0		47.5
Marketable Securities	20.5		0.3		0.1		0.6		25.9		0.4		0.1		0.6
Other Long-Term Assets	72.0		—		—		3.2		3.2		—		—		3.2
Cash and Restricted Cash reported on the Statements of Cash Flows	$	167.2	$	7.1	$	6.4	$	39.1	$	209.3	$	91.6	$	14.7	$	52.7

REGULATORY ACCOUNTING (Tables)

6 Months Ended

Jun. 30, 2019

Regulated Operations [Abstract]

Components of Regulatory Assets

The components of regulatory assets were as follows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Benefit Costs	$	1,870.5	$	407.4	$	554.8	$	151.1	$	1,914.8	$	424.7	$	544.4	$	169.6
Income Taxes, Net	702.6		456.5		104.1		10.1		728.6		454.4		105.9		8.3
Securitized Stranded Costs	586.9		—		—		586.9		608.4		—		—		608.4
Storm Restoration Costs, Net	536.7		279.6		191.2		65.9		576.0		302.6		212.9		60.5
Regulatory Tracker Mechanisms	289.0		60.3		138.2		70.6		316.0		33.2		169.1		67.3
Derivative Liabilities	347.9		345.4		—		—		356.5		356.5		—		—
Goodwill-related	340.0		—		291.9		—		348.4		—		299.1		—
Asset Retirement Obligations	97.1		33.3		48.3		3.5		89.2		32.3		42.2		3.3
Other Regulatory Assets	148.8		26.0		60.5		17.7		208.0		27.0		64.6		12.1
Total Regulatory Assets	4,919.5		1,608.5		1,389.0		905.8		5,145.9		1,630.7		1,438.2		929.5
Less: Current Portion	515.3		175.7		210.0		77.9		514.8		125.2		241.7		67.2
Total Long-Term Regulatory Assets	$	4,404.2	$	1,432.8	$	1,179.0	$	827.9	$	4,631.1	$	1,505.5	$	1,196.5	$	862.3

Components of Regulatory Liabilities

The components of regulatory liabilities were as follows:



	As of June 30, 2019								As of December 31, 2018
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
EDIT due to Tax Cuts and Jobs Act	$	2,860.7	$	1,028.7	$	1,090.0	$	395.4	$	2,883.0	$	1,031.0	$	1,103.7	$	396.4
Cost of Removal	544.9		51.0		319.4		21.4		521.0		39.9		307.1		22.1
Benefit Costs	83.8		—		70.9		—		91.2		—		76.9		—
Regulatory Tracker Mechanisms	333.3		110.0		141.9		31.2		309.0		89.5		163.7		48.3
AFUDC - Transmission	71.7		46.7		25.0		—		70.7		47.4		23.3		—
Revenue Subject to Refund due to Tax Cuts and Jobs Act	29.2		—		—		19.1		24.6		—		—		12.6
Other Regulatory Liabilities	96.1		29.4		38.6		4.1		80.2		24.0		29.2		4.2
Total Regulatory Liabilities	4,019.7		1,265.8		1,685.8		471.2		3,979.7		1,231.8		1,703.9		483.6
Less: Current Portion	379.9		112.4		171.0		54.2		370.2		109.6		190.6		55.5
Total Long-Term Regulatory Liabilities	$	3,639.8	$	1,153.4	$	1,514.8	$	417.0	$	3,609.5	$	1,122.2	$	1,513.3	$	428.1

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Tables)

6 Months Ended

Jun. 30, 2019

Property, Plant and Equipment [Abstract]

Public Utility Property, Plant, and Equipment

The following tables summarize property, plant and equipment by asset category:



Eversource	As of June 30, 2019			As of December 31, 2018
(Millions of Dollars)	As of June 30, 2019			As of December 31, 2018
Distribution - Electric	$	15,472.1		$	15,071.1
Distribution - Natural Gas	3,632.9			3,546.2
Transmission - Electric	10,449.5			10,153.9
Distribution - Water	1,664.1			1,639.8
Solar	196.9			164.1
Utility	31,415.5			30,575.1
Other ⁽¹⁾	882.4			778.6
Property, Plant and Equipment, Gross	32,297.9			31,353.7
Less: Accumulated Depreciation
Utility	(7,357.9		)	(7,126.2		)
Other	(363.1		)	(336.7		)
Total Accumulated Depreciation	(7,721.0		)	(7,462.9		)
Property, Plant and Equipment, Net	24,576.9			23,890.8
Construction Work in Progress	1,727.5			1,719.6
Total Property, Plant and Equipment, Net	$	26,304.4		$	25,610.4



	As of June 30, 2019									As of December 31, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Distribution - Electric	$	6,352.8		$	6,921.3		$	2,238.3		$	6,176.4		$	6,756.4		$	2,178.6
Transmission - Electric	4,880.6			4,148.8			1,415.2			4,700.5			4,065.9			1,338.7
Solar	—			196.9			—			—			164.1			—
Property, Plant and Equipment, Gross	11,233.4			11,267.0			3,653.5			10,876.9			10,986.4			3,517.3
Less: Accumulated Depreciation	(2,352.2		)	(2,814.9		)	(806.4		)	(2,302.6		)	(2,702.0		)	(772.9		)
Property, Plant and Equipment, Net	8,881.2			8,452.1			2,847.1			8,574.3			8,284.4			2,744.4
Construction Work in Progress	404.4			623.7			122.2			335.4			510.3			135.7
Total Property, Plant and Equipment, Net	$	9,285.6		$	9,075.8		$	2,969.3		$	8,909.7		$	8,794.7		$	2,880.1

⁽¹⁾

These assets are primarily comprised of building improvements, computer software, hardware and equipment at Eversource Service.

DERIVATIVE INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Gross Fair Values and Net Amounts of Contracts

The following table presents the gross fair values of contracts, categorized by risk type, and the net amounts recorded as current or long-term derivative assets or liabilities:



		As of June 30, 2019									As of December 31, 2018
(Millions of Dollars)	Fair Value Hierarchy	Commodity Supply and Price Risk Management			Netting ⁽¹⁾			Net Amount Recorded as a Derivative			Commodity Supply and Price Risk Management			Netting ⁽¹⁾			Net Amount Recorded as a Derivative
Current Derivative Assets:
CL&P	Level 3	$	11.1		$	(0.3	)	$	10.8		$	9.6		$	(3.4	)	$	6.2
Other	Level 2	—			—			—			1.5			(0.9		)	0.6
Long-Term Derivative Assets:
CL&P	Level 3	71.8			(2.2		)	69.6			74.2			(2.3		)	71.9
Current Derivative Liabilities:
CL&P	Level 3	(62.1		)	—			(62.1		)	(55.1		)	—			(55.1		)
Other	Level 2	(2.4		)	—			(2.4		)	—			—			—
Long-Term Derivative Liabilities:
CL&P	Level 3	(363.7		)	—			(363.7		)	(379.5		)	—			(379.5		)
Other	Level 2	(0.1		)	—			(0.1		)	—			—			—

⁽¹⁾

Amounts represent derivative assets and liabilities that Eversource elected to record net on the balance sheets. These amounts are subject to master netting agreements or similar agreements for which the right of offset exists.

Summary of Level 3 Derivative Contracts and Significant Observable Inputs Used

The following is a summary of Level 3 derivative contracts and the range of the significant unobservable inputs utilized in the valuations over the duration of the contracts:



	As of June 30, 2019						As of December 31, 2018
CL&P	Range					Period Covered	Range					Period Covered
Capacity Prices	$	4.30	—	7.34	per kW-Month	2023 - 2026	$	4.30	—	7.44	per kW-Month	2022 - 2026
Forward Reserve	0.75		—	1.78	per kW-Month	2019 - 2024	0.75		—	1.78	per kW-Month	2019 - 2024

Changes in the Level 3 Category of Derivative Assets Measured at Fair Value on a Recurring Basis

The following table presents changes in the Level 3 category of derivative assets and derivative liabilities measured at fair value on a recurring basis. The derivative assets and liabilities are presented on a net basis.



CL&P	For the Three Months Ended June 30,						For the Six Months Ended June 30,
(Millions of Dollars)	2019			2018			2019			2018
Derivatives, Net:
Fair Value as of Beginning of Period	$	(353.1	)	$	(386.5	)	$	(356.5	)	$	(362.3	)
Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets	(2.5		)	8.6			(7.8		)	(28.2		)
Settlements	10.2			8.6			18.9			21.2
Fair Value as of End of Period	$	(345.4	)	$	(369.3	)	$	(345.4	)	$	(369.3	)

MARKETABLE SECURITIES (Tables)

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Summary of Available-for-Sale Debt Securities

The following is a summary of the available-for-sale debt securities, which are recorded at fair value and are included in current and long-term Marketable Securities on the balance sheets.



	As of June 30, 2019									As of December 31, 2018
Eversource (Millions of Dollars)	Amortized Cost		Pre-Tax Unrealized Gains		Pre-Tax Unrealized Losses			Fair Value		Amortized Cost		Pre-Tax Unrealized Gains		Pre-Tax Unrealized Losses			Fair Value
Debt Securities	$	204.3	$	5.4	$	(0.1	)	$	209.6	$	190.0	$	0.4	$	(4.0	)	$	186.4

Contractual Maturities of Available-for-Sale Debt Securities

As of June 30, 2019, the contractual maturities of available-for-sale debt securities were as follows:



Eversource (Millions of Dollars)	Amortized Cost		Fair Value
Less than one year⁽¹⁾	$	26.9	$	26.9
One to five years	48.8		49.6
Six to ten years	38.4		40.0
Greater than ten years	90.2		93.1
Total Debt Securities	$	204.3	$	209.6

⁽¹⁾

Amounts in the Less than one year category include securities in the CYAPC and YAEC spent nuclear fuel trusts, which are restricted and are classified in long-term Marketable Securities on the balance sheets.

Marketable Securities Recorded at Fair Value on a Recurring Basis by Level

The following table presents the marketable securities recorded at fair value on a recurring basis by the level in which they are classified within the fair value hierarchy:



Eversource (Millions of Dollars)	As of June 30, 2019		As of December 31, 2018
Level 1:
Mutual Funds and Equities	$	203.7	$	244.0
Money Market Funds	20.5		25.9
Total Level 1	$	224.2	$	269.9
Level 2:
U.S. Government Issued Debt Securities (Agency and Treasury)	$	107.0	$	79.6
Corporate Debt Securities	46.1		39.5
Asset-Backed Debt Securities	13.4		14.0
Municipal Bonds	12.8		19.2
Other Fixed Income Securities	9.8		8.2
Total Level 2	$	189.1	$	160.5
Total Marketable Securities	$	413.3	$	430.4

SHORT-TERM AND LONG-TERM DEBT (Tables)

6 Months Ended

Jun. 30, 2019

Debt Disclosure [Abstract]

Borrowings Outstanding and Available under the Commecrial Paper Programs

The amount of borrowings outstanding and available under the commercial paper programs were as follows:



	Borrowings Outstanding as of				Available Borrowing Capacity as of				Weighted-Average Interest Rate as of
	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
(Millions of Dollars)	June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018		June 30, 2019		December 31, 2018
Eversource Parent Commercial Paper Program	$	566.0	$	631.5	$	884.0	$	818.5	2.55	%	2.77	%
NSTAR Electric Commercial Paper Program	163.0		278.5		487.0		371.5		2.42	%	2.50	%

Summary of Long-Term Debt Issuance and Repayments

The following table summarizes long-term debt issuances and repayments:



(Millions of Dollars)	Issue Date	Issuance/(Repayment)			Maturity Date	Use of Proceeds for Issuance/ Repayment Information
CL&P:
4.00% 2018 Series A First Mortgage Bonds ⁽¹⁾	April 2019	$	300.0		April 2048	Repaid short-term borrowings that were used to repay long-term debt that matured on February 1, 2019 and fund capital expenditures and working capital
5.50% 2009 Series A First Mortgage Bonds	February 2009	(250.0		)	February 2019	Repaid at maturity on February 1, 2019
NSTAR Electric:
3.25% 2019 Debentures	May 2019	400.0			May 2029	Repaid short-term borrowings that were used to fund investments in eligible green expenditures
PSNH:
3.60% 2019 Series T First Mortgage Bonds	June 2019	300.0			July 2049	Repay long-term debt due to mature in December 2019, repaid short-term borrowings and fund capital expenditures and working capital
Other:
NSTAR Gas 3.74% Series Q First Mortgage Bonds	July 2019	75.0			August 2049	Repaid short-term borrowings and fund capital expenditures and working capital

⁽¹⁾

These bonds are part of the same series issued by CL&P in March 2018. The aggregate outstanding principal amount of these bonds is now $800 million.

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES (Tables)

6 Months Ended

Jun. 30, 2019

Rate Reduction Bonds and Variable Interest Entity [Abstract]

Summary of the Impact of Funding on the Balance Sheets and Income Statements

The following tables summarize the impact of PSNH Funding on PSNH's balance sheets and income statements:



(Millions of Dollars)
Balance Sheet:	As of June 30, 2019		As of December 31, 2018
Restricted Cash - Current Portion (included in Prepayments and Other Current Assets)	$	35.0	$	47.5
Restricted Cash - Long-Term Portion (included in Other Long-Term Assets)	3.2		3.2
Securitized Stranded Costs (included in Regulatory Assets)	586.9		608.4
Other Regulatory Liabilities (included in Regulatory Liabilities)	7.9		5.8
Accrued Interest (included in Other Current Liabilities)	8.9		14.4
Rate Reduction Bonds - Current Portion	43.2		52.3
Rate Reduction Bonds - Long-Term Portion	561.7		583.3



(Millions of Dollars)	For the Three Months Ended				For the Six Months Ended
Income Statement:	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	$	10.8	$	6.8	$	21.5	$	6.8
Interest Expense on RRB Principal (included in Interest Expense)	5.3		2.8		10.7		2.8

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References + Details

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION (Tables)

6 Months Ended

Jun. 30, 2019

Postemployment Benefits [Abstract]

Components of Net Periodic Benefit Expense/(Income)

The components of net periodic benefit expense/(income) for the Pension, SERP and PBOP Plans, prior to amounts capitalized as Property, Plant and Equipment or deferred as regulatory assets for future recovery, are shown below. The service cost component of net periodic benefit expense, less the capitalized portion, is included in Operations and Maintenance expense on the statements of income. The remaining components of net periodic benefit expense/(income), less the deferred portion, are included in Other Income, Net on the statements of income. Pension, SERP and PBOP expense reflected in the statements of cash flows for CL&P, NSTAR Electric and PSNH does not include the intercompany allocations or the corresponding capitalized and deferred portion, as these amounts are cash settled on a short-term basis.



	Pension and SERP
	For the Three Months Ended June 30, 2019												For the Three Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	16.1		$	4.4		$	3.6		$	1.5		$	20.7		$	5.2		$	4.3		$	2.7
Interest Cost	54.8			11.4			12.3			6.0			49.1			10.5			10.9			5.5
Expected Return on Pension Plan Assets	(91.7		)	(18.1		)	(24.2		)	(10.1		)	(97.9		)	(19.4		)	(26.6		)	(10.8		)
Actuarial Loss	35.6			6.3			11.8			2.3			35.7			7.1			10.1			3.3
Prior Service Cost	0.3			—			—			—			2.1			0.2			0.1			0.1
Total Net Periodic Benefit Expense/(Income)	$	15.1		$	4.0		$	3.5		$	(0.3	)	$	9.7		$	3.6		$	(1.2	)	$	0.8
Intercompany Allocations	N/A			$	5.8		$	5.3		$	—		N/A			$	1.5		$	1.6		$	0.5

	Pension and SERP
	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	35.4		$	9.2		$	7.5		$	4.1		$	43.1		$	11.0		$	9.0		$	5.7
Interest Cost	109.1			23.0			24.2			12.2			97.8			20.9			21.7			10.9
Expected Return on Pension Plan Assets	(183.8		)	(36.9		)	(48.6		)	(20.4		)	(195.8		)	(40.2		)	(51.8		)	(21.8		)
Actuarial Loss	72.1			14.3			21.2			5.9			71.8			14.8			20.7			6.5
Prior Service Cost	0.6			—			0.1			—			4.1			0.6			0.1			0.2
Total Net Periodic Benefit Expense/(Income)	$	33.4		$	9.6		$	4.4		$	1.8		$	21.0		$	7.1		$	(0.3	)	$	1.5
Intercompany Allocations	N/A			$	13.6		$	8.4		$	2.5		N/A			$	3.0		$	3.2		$	1.0



	PBOP
	For the Three Months Ended June 30, 2019												For the Three Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	1.8		$	0.3		$	0.4		$	0.1		$	2.5		$	0.4		$	0.5		$	0.3
Interest Cost	8.2			1.6			2.4			0.8			6.8			1.5			2.2			0.9
Expected Return on Plan Assets	(16.8		)	(2.3		)	(7.5		)	(1.3		)	(16.7		)	(2.6		)	(8.1		)	(1.5		)
Actuarial Loss	1.6			0.3			0.7			—			1.6			0.4			0.4			0.2
Prior Service Cost/(Credit)	(5.8		)	0.3			(4.2		)	0.1			(5.7		)	0.3			(4.3		)	0.1
Total Net Periodic Benefit Expense/(Income)	$	(11.0	)	$	0.2		$	(8.2	)	$	(0.3	)	$	(11.5	)	$	—		$	(9.3	)	$	—
Intercompany Allocations	N/A			$	(0.3	)	$	(0.4	)	$	(0.1	)	N/A			$	(0.2	)	$	(0.3	)	$	(0.1	)

	PBOP
	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
(Millions of Dollars)	Eversource			CL&P			NSTAR Electric			PSNH			Eversource			CL&P			NSTAR Electric			PSNH
Service Cost	$	3.9		$	0.7		$	0.9		$	0.4		$	5.0		$	0.9		$	1.0		$	0.6
Interest Cost	16.3			3.1			4.7			1.7			14.4			2.9			4.4			1.6
Expected Return on Plan Assets	(33.4		)	(4.5		)	(15.1		)	(2.8		)	(34.8		)	(5.2		)	(16.2		)	(3.0		)
Actuarial Loss	4.1			0.7			1.7			0.2			4.4			0.8			1.1			0.4
Prior Service Cost/(Credit)	(11.6		)	0.5			(8.5		)	0.2			(11.5		)	0.5			(8.5		)	0.3
Total Net Periodic Benefit Expense/(Income)	$	(20.7	)	$	0.5		$	(16.3	)	$	(0.3	)	$	(22.5	)	$	(0.1	)	$	(18.2	)	$	(0.1	)
Intercompany Allocations	N/A			$	(0.4	)	$	(0.6	)	$	(0.2	)	N/A			$	(0.5	)	$	(0.7	)	$	(0.2	)

COMMITMENTS AND CONTINGENCIES (Tables)

6 Months Ended

Jun. 30, 2019

Commitments and Contingencies Disclosure [Abstract]

Environmental Sites and Related Reserves

The number of environmental sites and related reserves for which remediation or long-term monitoring, preliminary site work or site assessment is being performed are as follows:



	As of June 30, 2019			As of December 31, 2018
	Number of Sites	Reserve (in millions)		Number of Sites	Reserve (in millions)
Eversource	58	$	71.6	60	$	64.7
CL&P	15	5.8		15	5.4
NSTAR Electric	15	10.5		16	10.9
PSNH	9	5.4		9	5.4

Summary of Exposure to Guaruantees and Indemnifications

The following table summarizes Eversource parent's exposure to guarantees and indemnifications of its subsidiaries to external parties, as of June 30, 2019:



Company	Description	Maximum Exposure (in millions)		Expiration Dates
On behalf of subsidiaries:
Eversource Investment LLC	North East Offshore ⁽¹⁾	$	113.9	-
Various	Surety Bonds⁽²⁾	34.0		2019 - 2021
Rocky River Realty Company and Eversource Service	Lease Payments for Real Estate	7.1		2024
Bay State Wind	Real Estate Purchase	2.5		2020

⁽¹⁾

Eversource parent issued a declining balance guaranty on behalf of its subsidiary, Eversource Investment LLC, which holds an ownership interest in North East Offshore. Eversource parent will guarantee, as a primary obligor, the financial obligations, primarily all post-closing payment obligations of Eversource Investment LLC, under the Sale and Purchase Agreement and an Irrevocable Equity Commitment Letter with Ørsted. Eversource parent's obligations under the guaranty expire upon the full, final and indefeasible payment of the guaranteed obligations.

⁽²⁾

Surety bond expiration dates reflect termination dates, the majority of which will be renewed or extended. Certain surety bonds contain credit ratings triggers that would require Eversource parent to post collateral in the event that the unsecured debt credit ratings of Eversource parent are downgraded.

LEASES (Tables)

6 Months Ended

Jun. 30, 2019

Leases [Abstract]

Components of Lease Cost

The components of lease cost, prior to amounts capitalized, are as follows:



	For the Three Months Ended June 30, 2019								For the Six Months Ended June 30, 2019
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
Financing Lease Cost:
Amortization of Right-of-use-Assets	$	0.4	$	0.2	$	—	$	—	$	0.7	$	0.4	$	0.1	$	—
Interest on Lease Liabilities	0.3		0.1		0.2		—		0.7		0.3		0.3		—
Total Finance Lease Cost	0.7		0.3		0.2		—		1.4		0.7		0.4		—
Operating Lease Cost	2.9		0.1		0.5		—		5.9		0.1		0.9		—
Variable Lease Cost	15.7		3.1		—		12.6		31.1		6.5		—		24.6
Total Lease Cost	$	19.3	$	3.5	$	0.7	$	12.6	$	38.4	$	7.3	$	1.3	$	24.6

Supplemental Balance Sheet Information Related to Leases

Supplemental balance sheet information related to leases is as follows:



		As of June 30, 2019
(Millions of Dollars)	Balance Sheet Classification	Eversource		CL&P		NSTAR Electric		PSNH
Operating Leases:
Operating Lease Right-of-use-Assets, Net	Other Long-Term Assets	$	54.6	$	0.6	$	24.4	$	0.8
Operating Lease Liabilities
Operating Lease Liabilities - Current Portion	Other Current Liabilities	$	8.8	$	0.2	$	0.5	$	0.2
Operating Lease Liabilities - Long-Term	Other Long-Term Liabilities	45.8		0.4		23.9		0.6
Total Operating Lease Liabilities		$	54.6	$	0.6	$	24.4	$	0.8
Finance Leases:
Finance Lease Right-of-use-Assets, Net	Property, Plant and Equipment, Net	$	9.4	$	2.6	$	3.4	$	0.9
Finance Lease Liabilities
Finance Lease Liabilities - Current Portion	Other Current Liabilities	$	2.3	$	1.5	$	—	$	0.1
Finance Lease Liabilities - Long-Term	Other Long-Term Liabilities	9.3		2.3		4.4		0.8
Total Finance Lease Liabilities		$	11.6	$	3.8	$	4.4	$	0.9

Other Information Related to Leases

Other information related to leases is as follows (in millions of dollars, unless otherwise noted):



	Eversource			CL&P			NSTAR Electric			PSNH
As of June 30, 2019
Weighted-Average Remaining Lease Term (Years):
Operating Leases	12			4			21			8
Financing Leases	11			2			23			9
Weighted-Average Discount Rate (Percentage):
Operating Leases	3.9		%	2.7		%	4.1		%	3.6		%
Financing Leases	4.3		%	10.5		%	2.9		%	3.5		%

For the Three Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	3.0		$	0.1		$	0.5		$	—
Operating Cash Flows from Finance Leases	0.3			0.1			0.1			—
Financing Cash Flows from Finance Leases	0.5			0.4			—			—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.4			0.2			—			0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3			—			—			—



	Eversource		CL&P		NSTAR Electric		PSNH
For the Six Months Ended June 30, 2019
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$	5.9	$	0.1	$	0.8	$	—
Operating Cash Flows from Finance Leases	0.6		0.3		0.3		—
Financing Cash Flows from Finance Leases	0.9		0.7		—		—
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	1.7		0.2		—		0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	1.3		—		—		—

Future Minimum Lease Payments under Long-Term Leases

Future minimum lease payments, excluding variable costs, under long-term leases, as of June 30, 2019 are as follows:



	Operating Leases								Finance Leases
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
July 1, 2019 through December 31, 2019	$	5.7	$	0.3	$	0.8	$	0.2	$	1.7	$	1.0	$	0.3	$	0.1
Year Ending December 31,
2020	10.3		0.2		1.6		0.2		3.4		2.0		0.5		0.1
2021	9.2		0.1		1.6		0.2		2.9		1.5		0.5		0.1
2022	7.5		—		1.6		0.1		1.5		—		0.6		0.1
2023	4.9		—		1.6		0.1		0.7		—		0.6		0.1
2024	2.9		—		1.7		—		0.7		—		0.6		0.1
Thereafter	29.2		0.1		28.9		0.2		13.2		—		12.8		0.4
Future lease payments	69.7		0.7		37.8		1.0		24.1		4.5		15.9		1.0
Less amount representing interest	15.1		0.1		13.4		0.2		12.5		0.7		11.5		0.1
Present value of future minimum lease payments	$	54.6	$	0.6	$	24.4	$	0.8	$	11.6	$	3.8	$	4.4	$	0.9

Future Minimum Lease Payments under Long-Term Leases

Future minimum lease payments, excluding variable costs, under long-term leases, as of June 30, 2019 are as follows:



	Operating Leases								Finance Leases
(Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH		Eversource		CL&P		NSTAR Electric		PSNH
July 1, 2019 through December 31, 2019	$	5.7	$	0.3	$	0.8	$	0.2	$	1.7	$	1.0	$	0.3	$	0.1
Year Ending December 31,
2020	10.3		0.2		1.6		0.2		3.4		2.0		0.5		0.1
2021	9.2		0.1		1.6		0.2		2.9		1.5		0.5		0.1
2022	7.5		—		1.6		0.1		1.5		—		0.6		0.1
2023	4.9		—		1.6		0.1		0.7		—		0.6		0.1
2024	2.9		—		1.7		—		0.7		—		0.6		0.1
Thereafter	29.2		0.1		28.9		0.2		13.2		—		12.8		0.4
Future lease payments	69.7		0.7		37.8		1.0		24.1		4.5		15.9		1.0
Less amount representing interest	15.1		0.1		13.4		0.2		12.5		0.7		11.5		0.1
Present value of future minimum lease payments	$	54.6	$	0.6	$	24.4	$	0.8	$	11.6	$	3.8	$	4.4	$	0.9

Future Minimum Rental Payments under Operating Leases

At December 31, 2018, future minimum rental payments, excluding executory costs, such as property taxes, state use taxes, insurance, and maintenance were as follows:



Operating Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	11.5	$	1.5	$	7.2	$	0.5
2020	9.8		1.4		6.0		0.4
2021	8.7		1.2		5.3		0.4
2022	7.2		1.1		4.4		0.4
2023	4.7		0.5		3.1		0.2
Thereafter	32.7		0.2		29.5		0.3
Future minimum lease payments	$	74.6	$	5.9	$	55.5	$	2.2



Capital Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	3.4	$	2.0	$	0.5	$	0.1
2020	3.4		2.0		0.5		0.1
2021	2.9		1.5		0.5		0.1
2022	1.5		—		0.6		0.1
2023	0.7		—		0.6		0.1
Thereafter	13.9		—		13.4		0.5
Future minimum lease payments	25.8		5.5		16.1		1.0
Less amount representing interest	13.8		1.0		12.4		0.1
Present value of future minimum lease payments	$	12.0	$	4.5	$	3.7	$	0.9

Future Minimum Rental Payments under Capital Leases



Capital Leases (Millions of Dollars)	Eversource		CL&P		NSTAR Electric		PSNH
2019	$	3.4	$	2.0	$	0.5	$	0.1
2020	3.4		2.0		0.5		0.1
2021	2.9		1.5		0.5		0.1
2022	1.5		—		0.6		0.1
2023	0.7		—		0.6		0.1
Thereafter	13.9		—		13.4		0.5
Future minimum lease payments	25.8		5.5		16.1		1.0
Less amount representing interest	13.8		1.0		12.4		0.1
Present value of future minimum lease payments	$	12.0	$	4.5	$	3.7	$	0.9

FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2019

Fair Value Disclosures [Abstract]

Carrying Amounts and Estimated Fair Values of Financial Instruments

Carrying amounts and estimated fair values are as follows:



	Eversource				CL&P				NSTAR Electric				PSNH
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value		Carrying Amount		Fair Value
As of June 30, 2019:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	161.0	$	116.2	$	117.4	$	43.0	$	43.6	$	—	$	—
Long-Term Debt	13,818.5		14,639.4		3,309.5		3,724.9		3,341.5		3,599.6		1,101.8		1,145.3
Rate Reduction Bonds	604.9		642.2		—		—		—		—		604.9		642.2

As of December 31, 2018:
Preferred Stock Not Subject to Mandatory Redemption	$	155.6	$	156.8	$	116.2	$	113.8	$	43.0	$	43.0	$	—	$	—
Long-Term Debt	13,086.1		13,154.9		3,254.0		3,429.2		2,944.8		3,024.1		805.2		819.5
Rate Reduction Bonds	635.7		645.8		—		—		—		—		635.7		645.8

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Tables)

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Changes in Accumulated Other Comprehensive Income/(Loss) by Component, Net of Tax

The changes in accumulated other comprehensive income/(loss) by component, net of tax, are as follows:



	For the Six Months Ended June 30, 2019												For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Qualified Cash Flow Hedging Instruments			Unrealized Gains/(Losses) on Marketable Securities			Defined Benefit Plans			Total			Qualified Cash Flow Hedging Instruments			Unrealized Losses on Marketable Securities			Defined Benefit Plans			Total
Balance as of January 1st	$	(4.4	)	$	(0.5	)	$	(55.1	)	$	(60.0	)	$	(6.2	)	$	—		$	(60.2	)	$	(66.4	)

OCI Before Reclassifications	—			1.1			2.6			3.7			—			(0.6		)	2.6			2.0
Amounts Reclassified from AOCI	0.6			—			2.1			2.7			1.2			—			2.2			3.4
Net OCI	0.6			1.1			4.7			6.4			1.2			(0.6		)	4.8			5.4
Balance as of June 30th	$	(3.8	)	$	0.6		$	(50.4	)	$	(53.6	)	$	(5.0	)	$	(0.6	)	$	(55.4	)	$	(61.0	)

COMMON SHARES (Tables)

6 Months Ended

Jun. 30, 2019

Equity [Abstract]

Common Shares Authorized and Issued

The following table sets forth the Eversource parent common shares and the shares of common stock of CL&P, NSTAR Electric and PSNH that were authorized and issued, as well as the respective per share par values:



	Shares
			Authorized as of June 30, 2019 and December 31, 2018	Issued as of
	Par Value		Authorized as of June 30, 2019 and December 31, 2018	June 30, 2019	December 31, 2018
Eversource	$	5	380,000,000	339,858,402	333,878,402
CL&P	$	10	24,500,000	6,035,205	6,035,205
NSTAR Electric	$	1	100,000,000	200	200
PSNH	$	1	100,000,000	301	301

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

+ References

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+ Details

EARNINGS PER SHARE (Tables)

6 Months Ended

Jun. 30, 2019

Earnings Per Share [Abstract]

Components of Basic and Diluted EPS

The following table sets forth the components of basic and diluted EPS:



Eversource (Millions of Dollars, except share information)	For the Three Months Ended				For the Six Months Ended
Eversource (Millions of Dollars, except share information)	June 30, 2019		June 30, 2018		June 30, 2019		June 30, 2018
Net Income Attributable to Common Shareholders	$	31.5	$	242.8	$	340.1	$	512.3
Weighted Average Common Shares Outstanding:
Basic	319,664,998		317,344,596		318,644,796		317,370,825
Dilutive Effect of:
Share-Based Compensation Awards and Other	645,450		540,591		668,470		568,269
Equity Forward Sale Agreement	78,042		—		39,021		—
Total Dilutive Effect	723,492		540,591		707,491		568,269
Diluted	320,388,490		317,885,187		319,352,287		317,939,094
Basic and Diluted EPS	$	0.10	$	0.76	$	1.07	$	1.61

REVENUES (Tables)

6 Months Ended

Jun. 30, 2019

Revenue from Contract with Customer [Abstract]

Operating Revenues Disaggregated by Revenue Source

The following tables present operating revenues disaggregated by revenue source:



	For the Three Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission		Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	805.0		$	100.2		$	—	$	33.6		$	—	$	—		$	938.8
Commercial	612.8			69.5			—		16.0			—		(0.9		)	697.4
Industrial	81.3			23.5			—		1.1			—		(2.8		)	103.1
Total Retail Tariff Sales Revenues	1,499.1			193.2			—		50.7			—		(3.7		)	1,739.3
Wholesale Transmission Revenues	—			—			281.2		—			14.7		(239.8		)	56.1
Wholesale Market Sales Revenues	39.4			14.4			—		0.9			—		—			54.7
Other Revenues from Contracts with Customers	15.1			0.4			3.7		1.8			236.1		(236.8		)	20.3
Reserve for Revenues Subject to Refund	(3.1		)	1.5			—		(0.6		)	—		—			(2.2		)
Total Revenues from Contracts with Customers	1,550.5			209.5			284.9		52.8			250.8		(480.3		)	1,868.2
Alternative Revenue Programs	6.3			(2.7		)	64.6		0.7			—		(58.8		)	10.1
Other Revenues ⁽¹⁾	5.0			0.9			0.1		0.2			—		—			6.2
Total Operating Revenues	$	1,561.8		$	207.7		$	349.6	$	53.7		$	250.8	$	(539.1	)	$	1,884.5


	For the Six Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission		Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	1,838.3		$	359.1		$	—	$	60.5		$	—	$	—		$	2,257.9
Commercial	1,265.3			213.3			—		30.3			—		(2.0		)	1,506.9
Industrial	163.4			54.4			—		2.2			—		(5.5		)	214.5
Total Retail Tariff Sales Revenues	3,267.0			626.8			—		93.0			—		(7.5		)	3,979.3
Wholesale Transmission Revenues	—			—			606.1		—			28.3		(510.7		)	123.7
Wholesale Market Sales Revenues	90.8			36.1			—		1.9			—		—			128.8
Other Revenues from Contracts with Customers	27.7			1.4			6.9		3.5			480.7		(482.2		)	38.0
Reserve for Revenues Subject to Refund	(6.1		)	3.1			—		(1.2		)	—		—			(4.2		)
Total Revenues from Contracts with Customers	3,379.4			667.4			613.0		97.2			509.0		(1,000.4		)	4,265.6
Alternative Revenue Programs	8.4			7.7			77.0		1.5			—		(69.8		)	24.8
Other Revenues ⁽¹⁾	7.8			1.5			0.1		0.5			—		—			9.9
Total Operating Revenues	$	3,395.6		$	676.6		$	690.1	$	99.2		$	509.0	$	(1,070.2	)	$	4,300.3



	For the Three Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	794.4		$	104.1		$	—		$	32.3		$	—	$	—		$	930.8
Commercial	622.0			70.0			—			15.7			—		(2.0		)	705.7
Industrial	88.4			23.5			—			1.1			—		(2.4		)	110.6
Total Retail Tariff Sales Revenues	1,504.8			197.6			—			49.1			—		(4.4		)	1,747.1
Wholesale Transmission Revenues	—			—			310.8			—			12.6		(268.0		)	55.4
Wholesale Market Sales Revenues	34.2			12.1			—			0.9			—		—			47.2
Other Revenues from Contracts with Customers	18.4			(0.6		)	3.2			1.9			224.4		(225.1		)	22.2
Reserve for Revenues Subject to Refund	(7.3		)	(3.5		)	—			(0.5		)	—		—			(11.3		)
Total Revenues from Contracts with Customers	1,550.1			205.6			314.0			51.4			237.0		(497.5		)	1,860.6
Alternative Revenue Programs	(14.4		)	0.1			3.4			1.9			—		(2.9		)	(11.9		)
Other Revenues	4.2			0.8			—			0.2			—		—			5.2
Total Operating Revenues	$	1,539.9		$	206.5		$	317.4		$	53.5		$	237.0	$	(500.4	)	$	1,853.9


	For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other		Eliminations			Total
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	1,788.7		$	352.9		$	—		$	59.7		$	—	$	—		$	2,201.3
Commercial	1,233.4			204.7			—			30.0			—		(2.1		)	1,466.0
Industrial	169.9			53.1			—			2.1			—		(5.0		)	220.1
Total Retail Tariff Sales Revenues	3,192.0			610.7			—			91.8			—		(7.1		)	3,887.4
Wholesale Transmission Revenues	—			—			624.5			—			22.7		(526.7		)	120.5
Wholesale Market Sales Revenues	92.7			29.9			—			1.7			—		—			124.3
Other Revenues from Contracts with Customers	35.3			(0.9		)	6.2			3.7			445.2		(446.3		)	43.2
Reserve for Revenues Subject to Refund	(26.5		)	(8.0		)	—			(2.0		)	—		—			(36.5		)
Total Revenues from Contracts with Customers	3,293.5			631.7			630.7			95.2			467.9		(980.1		)	4,138.9
Alternative Revenue Programs	(5.7		)	(1.7		)	(8.3		)	2.6			—		7.7			(5.4		)
Other Revenues	6.7			1.4			—			0.2			—		—			8.3
Total Operating Revenues	$	3,294.5		$	631.4		$	622.4		$	98.0		$	467.9	$	(972.4	)	$	4,141.8



	For the Three Months Ended June 30, 2019									For the Three Months Ended June 30, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	402.8		$	282.3		$	119.9		$	387.1		$	292.5		$	114.8
Commercial	224.7			315.8			72.7			220.7			325.5			76.2
Industrial	33.8			28.9			18.6			36.5			30.9			21.0
Total Retail Tariff Sales Revenues	661.3			627.0			211.2			644.3			648.9			212.0
Wholesale Transmission Revenues	115.9			127.5			37.8			139.9			120.9			50.1
Wholesale Market Sales Revenues	12.1			17.2			10.1			10.6			13.4			10.9
Other Revenues from Contracts with Customers	9.1			6.1			4.2			8.3			9.3			3.9
Reserve for Revenues Subject to Refund	—			—			(3.1		)	(4.2		)	—			(3.1		)
Total Revenues from Contracts with Customers	798.4			777.8			260.2			798.9			792.5			273.8
Alternative Revenue Programs	55.1			2.1			13.7			1.0			(6.9		)	(5.0		)
Other Revenues ⁽¹⁾	2.7			1.9			0.5			2.4			1.6			0.2
Eliminations	(115.4		)	(99.9		)	(33.5		)	(107.4		)	(96.5		)	(33.9		)
Total Operating Revenues	$	740.8		$	681.9		$	240.9		$	694.9		$	690.7		$	235.1

	For the Six Months Ended June 30, 2019									For the Six Months Ended June 30, 2018
(Millions of Dollars)	CL&P			NSTAR Electric			PSNH			CL&P			NSTAR Electric			PSNH
Revenues from Contracts with Customers
Retail Tariff Sales
Residential	$	913.4		$	653.2		$	271.7		$	870.4		$	656.7		$	261.6
Commercial	461.3			652.3			152.6			443.2			640.0			151.1
Industrial	68.4			57.8			37.2			72.3			59.0			38.6
Total Retail Tariff Sales Revenues	1,443.1			1,363.3			461.5			1,385.9			1,355.7			451.3
Wholesale Transmission Revenues	270.7			250.1			85.3			290.6			239.5			94.3
Wholesale Market Sales Revenues	25.8			41.6			23.4			21.0			38.2			34.9
Other Revenues from Contracts with Customers	18.0			10.1			7.8			16.2			18.3			7.5
Reserve for Revenues Subject to Refund	—			—			(6.1		)	(16.6		)	(3.7		)	(6.2		)
Total Revenues from Contracts with Customers	1,757.6			1,665.1			571.9			1,697.1			1,648.0			581.8
Alternative Revenue Programs	60.9			9.3			15.2			(4.1		)	(0.2		)	(9.6		)
Other Revenues ⁽¹⁾	3.7			3.4			0.8			3.3			2.7			0.6
Eliminations	(232.1		)	(198.3		)	(70.6		)	(216.4		)	(189.6		)	(70.3		)
Total Operating Revenues	$	1,590.1		$	1,479.5		$	517.3		$	1,479.9		$	1,460.9		$	502.5

⁽¹⁾

Other Revenues include certain fees charged to customers, which are not considered revenue from contracts with customers. Other revenues also includes lease revenues under lessor accounting guidance of $1.1 million at Eversource, $0.3 million at CL&P, and $0.7 million at NSTAR Electric for the three months ended June 30, 2019, and $2.2 million at Eversource, $0.5 million at CL&P, and $1.3 million at NSTAR Electric for the six months ended June 30, 2019, respectively.

SEGMENT INFORMATION (Tables)

6 Months Ended

Jun. 30, 2019

Segment Reporting [Abstract]

Summary of Segment Information and Segmented Total Assets

Eversource's segment information is as follows:



	For the Three Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	1,561.8		$	207.7		$	349.6		$	53.7		$	250.8		$	(539.1	)	$	1,884.5
Depreciation and Amortization	(150.1		)	(19.5		)	(62.3		)	(12.0		)	(14.7		)	0.6			(258.0		)
Impairment of Northern Pass Transmission	—			—			(239.6		)	—			—			—			(239.6		)
Other Operating Expenses	(1,243.0		)	(179.8		)	(108.4		)	(25.0		)	(218.4		)	538.7			(1,235.9		)
Operating Income/(Loss)	$	168.7		$	8.4		$	(60.7	)	$	16.7		$	17.7		$	0.2		$	151.0
Interest Expense	$	(50.8	)	$	(11.9	)	$	(30.5	)	$	(8.6	)	$	(44.5	)	$	13.6		$	(132.7	)
Other Income/(Loss), Net	12.2			0.7			8.7			0.1			(114.9		)	139.1			45.9
Net Income/(Loss) Attributable to Common Shareholders	105.4			(1.8		)	(87.4		)	8.0			(145.6		)	152.9			31.5


	For the Six Months Ended June 30, 2019
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	3,395.6		$	676.6		$	690.1		$	99.2		$	509.0		$	(1,070.2	)	$	4,300.3
Depreciation and Amortization	(329.3		)	(39.9		)	(123.7		)	(23.9		)	(28.3		)	1.1			(544.0		)
Impairment of Northern Pass Transmission	—			—			(239.6		)	—			—			—			(239.6		)
Other Operating Expenses	(2,718.6		)	(521.1		)	(207.2		)	(49.9		)	(444.0		)	1,069.8			(2,871.0		)
Operating Income	$	347.7		$	115.6		$	119.6		$	25.4		$	36.7		$	0.7		$	645.7
Interest Expense	$	(100.0	)	$	(23.7	)	$	(61.0	)	$	(17.2	)	$	(88.6	)	$	26.1		$	(264.4	)
Other Income, Net	30.4			1.0			16.8			0.4			316.8			(288.5		)	76.9
Net Income Attributable to Common Shareholders	225.4			74.7			30.9			8.8			262.0			(261.7		)	340.1
Cash Flows Used for Investments in Plant	571.3			202.7			449.2			51.4			103.2			—			1,377.8



	For the Three Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	1,539.9		$	206.5		$	317.4		$	53.5		$	237.0		$	(500.4	)	$	1,853.9
Depreciation and Amortization	(135.5		)	(19.3		)	(57.0		)	(12.2		)	(11.9		)	0.6			(235.3		)
Other Operating Expenses	(1,233.0		)	(170.6		)	(88.8		)	(24.5		)	(211.7		)	501.4			(1,227.2		)
Operating Income	$	171.4		$	16.6		$	171.6		$	16.8		$	13.4		$	1.6		$	391.4
Interest Expense	$	(52.1	)	$	(11.4	)	$	(30.0	)	$	(8.6	)	$	(32.3	)	$	8.0		$	(126.4	)
Other Income/(Loss), Net	19.0			1.6			9.9			(0.6		)	302.0			(281.8		)	50.1
Net Income Attributable to Common Shareholders	101.3			5.0			112.7			7.2			288.8			(272.2		)	242.8

	For the Six Months Ended June 30, 2018
Eversource (Millions of Dollars)	Electric Distribution			Natural Gas Distribution			Electric Transmission			Water Distribution			Other			Eliminations			Total
Operating Revenues	$	3,294.5		$	631.4		$	622.4		$	98.0		$	467.9		$	(972.4	)	$	4,141.8
Depreciation and Amortization	(279.9		)	(45.7		)	(113.5		)	(22.9		)	(23.9		)	1.1			(484.8		)
Other Operating Expenses	(2,676.5		)	(483.2		)	(172.0		)	(48.4		)	(416.3		)	973.3			(2,823.1		)
Operating Income	$	338.1		$	102.5		$	336.9		$	26.7		$	27.7		$	2.0		$	833.9
Interest Expense	$	(99.5	)	$	(22.5	)	$	(59.7	)	$	(16.9	)	$	(64.3	)	$	15.4		$	(247.5	)
Other Income/(Loss), Net	38.6			3.5			17.8			(1.1		)	662.1			(637.0		)	83.9
Net Income Attributable to Common Shareholders	205.5			62.8			220.1			8.7			634.8			(619.6		)	512.3
Cash Flows Used for Investments in Plant	475.6			150.3			508.5			40.2			77.1			—			1,251.7

The following table summarizes Eversource's segmented total assets:



Eversource (Millions of Dollars)	Electric Distribution		Natural Gas Distribution		Electric Transmission		Water Distribution		Other		Eliminations			Total
As of June 30, 2019	$	21,628.8	$	4,031.3	$	10,499.7	$	2,290.5	$	18,550.4	$	(18,004.8	)	$	38,995.9
As of December 31, 2018	21,389.1		3,904.9		10,285.0		2,253.0		17,874.2		(17,464.9		)	38,241.3

For further information regarding the 2019 impairment of NPT, see Note 1C, "Summary of Significant Accounting Policies - Impairment of Northern Pass Transmission," to the financial statements.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ / shares in Units, $ in Thousands, customer in Millions		1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 19, 2019 USD ($)	Jul. 31, 2019 USD ($)	Jun. 30, 2019 USD ($) $ / shares	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) utility customer $ / shares MW	Jun. 30, 2018 USD ($)	Feb. 08, 2019 USD ($) mi²	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Summary of Accounting Policies [Line Items]
Number of electric, natural gas and water customers \| customer					4,000,000
Operating lease liability			$ 54,600		$ 54,600
Operating lease right-of-use asset			54,600		54,600
Pre-tax impairment charge			239,644	$ 0	239,644	$ 0
After-tax impact of impairment charge			$ 204,400		$ 204,400
After-tax impact of impairment charge (in dollars per share) \| $ / shares			$ 0.64		$ 0.64
Equity investment balance			$ 748,705		$ 748,705				$ 464,286
Energy efficiency funds collected from customers to be remitted to the State of Connecticut			10,700	$ 12,700	21,400	25,400
Capital contribution					$ 265,955	$ 13,220
Northern Pass
Summary of Accounting Policies [Line Items]
Capacity required for transmission line \| MW					1,090
Northern Pass \| Subsequent Event
Summary of Accounting Policies [Line Items]
Pre-tax impairment charge	$ 318,000
Revolution Wind and South Fork Wind
Summary of Accounting Policies [Line Items]
Cost of investment in unconsolidated affiliate							$ 225,000
Ownership interest							50.00%
Area of land \| mi²							257
Equity investment balance			499,500		$ 499,500
Revolution Wind and South Fork Wind \| Subsequent Event
Summary of Accounting Policies [Line Items]
Capital contribution		$ 54,900
Bay State Wind
Summary of Accounting Policies [Line Items]
Ownership interest							50.00%
ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability								$ 58,000
Operating lease right-of-use asset								58,000
NSTAR Electric
Summary of Accounting Policies [Line Items]
Operating lease liability			24,400		24,400
Operating lease right-of-use asset			24,400		24,400
NSTAR Electric \| ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability								25,300
Operating lease right-of-use asset								25,300
CL&P
Summary of Accounting Policies [Line Items]
Operating lease liability			600		600
Operating lease right-of-use asset			600		$ 600
Period of accounts receivable recoverable under financial or medical duress					180 days
CL&P \| ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability								600
Operating lease right-of-use asset								600
PSNH
Summary of Accounting Policies [Line Items]
Operating lease liability			800		$ 800
Operating lease right-of-use asset			$ 800		$ 800
PSNH \| ASU 2016-02
Summary of Accounting Policies [Line Items]
Operating lease liability								600
Operating lease right-of-use asset								$ 600
Yankee Gas
Summary of Accounting Policies [Line Items]
Period of accounts receivable recoverable under financial or medical duress					90 days
Connecticut, Massachusetts and New Hampshire
Summary of Accounting Policies [Line Items]
Number of regulated utilities \| utility					8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for Uncollectible Accounts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	$ 226,400		$ 226,400		$ 212,700
Provision for Uncollectible Hardship Accounts	137,900		137,900		131,500
Bad debt expense associated with accounts receivable	13,000	$ 9,500	31,546	$ 29,250
CL&P
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	88,700		88,700		88,000
Provision for Uncollectible Hardship Accounts	70,900		70,900		71,900
Bad debt expense associated with accounts receivable	3,500	3,800	7,627	7,747
NSTAR Electric
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	81,800		81,800		74,500
Provision for Uncollectible Hardship Accounts	47,700		47,700		42,500
Bad debt expense associated with accounts receivable	5,700	3,800	11,605	11,301
PSNH
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Provision for Uncollectible Accounts	11,200		11,200		11,100
Provision for Uncollectible Hardship Accounts	0		0		$ 0
Bad debt expense associated with accounts receivable	$ 1,400	$ 1,500	$ 3,100	$ 3,200

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Components of Other Income, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Summary of Accounting Policies [Line Items]
Other income, net	$ 45,866	$ 50,149	$ 76,850	$ 83,938
Pension, SERP and PBOP Non-Service Income/(Expense) Components
Summary of Accounting Policies [Line Items]
Other income, net	5,800	14,600	13,100	29,800
AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	13,100	10,900	24,100	20,600
Equity in Earnings
Summary of Accounting Policies [Line Items]
Other income, net	25,900	22,900	30,900	27,500
Unrealized gain associated with investment	20,400	17,600	20,400	17,600
Investment Income
Summary of Accounting Policies [Line Items]
Other income, net	(600)	(300)	600	400
Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	1,300	1,900	7,800	5,400
Other
Summary of Accounting Policies [Line Items]
Other income, net	400	100	400	200
CL&P
Summary of Accounting Policies [Line Items]
Other income, net	2,853	7,063	6,733	13,623
CL&P \| Pension, SERP and PBOP Non-Service Income/(Expense) Components
Summary of Accounting Policies [Line Items]
Other income, net	(900)	2,400	(1,600)	5,300
CL&P \| AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	3,200	3,300	5,800	6,100
CL&P \| Equity in Earnings
Summary of Accounting Policies [Line Items]
Other income, net	100	0	100	0
CL&P \| Investment Income
Summary of Accounting Policies [Line Items]
Other income, net	(100)	400	1,700	200
CL&P \| Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	500	1,000	800	2,000
CL&P \| Other
Summary of Accounting Policies [Line Items]
Other income, net	100	0	(100)	0
NSTAR Electric
Summary of Accounting Policies [Line Items]
Other income, net	10,657	14,269	21,743	26,870
NSTAR Electric \| Pension, SERP and PBOP Non-Service Income/(Expense) Components
Summary of Accounting Policies [Line Items]
Other income, net	5,400	9,500	12,400	17,900
NSTAR Electric \| AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	5,100	3,900	9,100	7,300
NSTAR Electric \| Equity in Earnings
Summary of Accounting Policies [Line Items]
Other income, net	200	400	400	400
NSTAR Electric \| Investment Income
Summary of Accounting Policies [Line Items]
Other income, net	(300)	300	(600)	900
NSTAR Electric \| Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	200	200	400	400
NSTAR Electric \| Other
Summary of Accounting Policies [Line Items]
Other income, net	100	0	0	0
PSNH
Summary of Accounting Policies [Line Items]
Other income, net	2,984	3,409	10,006	8,159
PSNH \| Pension, SERP and PBOP Non-Service Income/(Expense) Components
Summary of Accounting Policies [Line Items]
Other income, net	1,500	2,100	2,000	4,400
PSNH \| AFUDC Equity
Summary of Accounting Policies [Line Items]
Other income, net	900	0	1,100	0
PSNH \| Equity in Earnings
Summary of Accounting Policies [Line Items]
Other income, net	0	0	0	0
PSNH \| Investment Income
Summary of Accounting Policies [Line Items]
Other income, net	(100)	0	200	100
PSNH \| Interest Income
Summary of Accounting Policies [Line Items]
Other income, net	700	1,300	6,600	3,700
PSNH \| Other
Summary of Accounting Policies [Line Items]
Other income, net	$ 0	$ 0	$ 100	$ 0

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 36.4	$ 35.6	$ 81.4	$ 79.0
CL&P
Schedule of Gross Tax Receipts [Line Items]
Gross receipts taxes	$ 31.8	$ 31.5	$ 68.0	$ 67.1

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Non-cash Investing Activities (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 323.7	$ 305.7
CL&P
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	114.0	110.9
NSTAR Electric
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	85.2	71.1
PSNH
Schedule of Supplemental Cash Flow [Line Items]
Plant additions included in accounts payable	$ 29.9	$ 46.6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash Balances to Cash and Restricted Cash (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	$ 20,578	$ 108,068
Cash and Restricted Cash reported on the Statements of Cash Flows	167,163	209,324	$ 121,850	$ 85,890
Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	54,100	72,100
Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	20,500	25,900
Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	72,000	3,200
CL&P
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	2,191	87,721
Cash and Restricted Cash reported on the Statements of Cash Flows	7,094	91,613	5,695	9,619
CL&P \| Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	4,600	3,500
CL&P \| Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	300	400
CL&P \| Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
NSTAR Electric
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	177	1,606
Cash and Restricted Cash reported on the Statements of Cash Flows	6,366	14,659	13,100	14,708
NSTAR Electric \| Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	6,100	13,000
NSTAR Electric \| Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	100	100
NSTAR Electric \| Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	0	0
PSNH
Restricted Cash and Cash Equivalents Items [Line Items]
Cash as reported on the Balance Sheets	343	1,439
Cash and Restricted Cash reported on the Statements of Cash Flows	39,087	52,723	$ 8,501	$ 2,191
PSNH \| Prepayments and Other Current Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	35,000	47,500
PSNH \| Marketable Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	600	600
PSNH \| Other Long-Term Assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 3,200	$ 3,200

REGULATORY ACCOUNTING - Components of Regulatory Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 4,919,500	$ 5,145,900
Less: Current Portion	515,265	514,779
Total Long-Term Regulatory Assets	4,404,176	4,631,137
Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	1,870,500	1,914,800
Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	702,600	728,600
Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	586,900	608,400
Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	536,700	576,000
Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	289,000	316,000
Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	347,900	356,500
Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	340,000	348,400
Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	97,100	89,200
Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	148,800	208,000
CL&P
Regulatory Assets [Line Items]
Total Regulatory Assets	1,608,500	1,630,700
Less: Current Portion	175,706	125,155
Total Long-Term Regulatory Assets	1,432,827	1,505,488
CL&P \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	407,400	424,700
CL&P \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	456,500	454,400
CL&P \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P \| Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	279,600	302,600
CL&P \| Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	60,300	33,200
CL&P \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	345,400	356,500
CL&P \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
CL&P \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	33,300	32,300
CL&P \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	26,000	27,000
NSTAR Electric
Regulatory Assets [Line Items]
Total Regulatory Assets	1,389,000	1,438,200
Less: Current Portion	210,032	241,747
Total Long-Term Regulatory Assets	1,178,974	1,196,512
NSTAR Electric \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	554,800	544,400
NSTAR Electric \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	104,100	105,900
NSTAR Electric \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric \| Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	191,200	212,900
NSTAR Electric \| Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	138,200	169,100
NSTAR Electric \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
NSTAR Electric \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	291,900	299,100
NSTAR Electric \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	48,300	42,200
NSTAR Electric \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	60,500	64,600
PSNH
Regulatory Assets [Line Items]
Total Regulatory Assets	905,800	929,500
Less: Current Portion	77,854	67,228
Total Long-Term Regulatory Assets	827,898	862,288
PSNH \| Benefit Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	151,100	169,600
PSNH \| Income Taxes, Net
Regulatory Assets [Line Items]
Total Regulatory Assets	10,100	8,300
PSNH \| Securitized Stranded Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	586,900	608,400
PSNH \| Storm Restoration Costs
Regulatory Assets [Line Items]
Total Regulatory Assets	65,900	60,500
PSNH \| Regulatory Tracker Mechanisms
Regulatory Assets [Line Items]
Total Regulatory Assets	70,600	67,300
PSNH \| Derivative Liabilities
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH \| Goodwill-related
Regulatory Assets [Line Items]
Total Regulatory Assets	0	0
PSNH \| Asset Retirement Obligations
Regulatory Assets [Line Items]
Total Regulatory Assets	3,500	3,300
PSNH \| Other Regulatory Assets
Regulatory Assets [Line Items]
Total Regulatory Assets	$ 17,700	$ 12,100

REGULATORY ACCOUNTING - Narrative (Details) - USD ($) $ in Thousands			3 Months Ended			6 Months Ended
	Jun. 27, 2019	May 01, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 17, 2019	Apr. 16, 2019	Mar. 26, 2019	Dec. 31, 2018	Nov. 16, 2018
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved			$ 142,000			$ 142,000					$ 122,900
Regulatory assets			4,919,500			4,919,500					5,145,900
Other income, net			45,866		$ 50,149	76,850	$ 83,938
CL&P
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved			43,600			43,600					42,100
Regulatory assets			1,608,500			1,608,500					1,630,700
Other income, net			2,853		7,063	6,733	13,623
CL&P \| Storm Costs
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved									$ 145,500			$ 153,000
Recovery period		6 years
Regulatory assets								$ 141,000
PSNH
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved			15,300			15,300					12,200
Regulatory assets			905,800			905,800					929,500
Other income, net			2,984		3,409	10,006	8,159
PSNH \| Storm Costs
Regulatory Assets [Line Items]
Recovery period	5 years
Regulatory assets	$ 68,500									$ 38,100
PSNH \| Deferred Costs from Generation Asset Sale
Regulatory Assets [Line Items]
Other income, net				$ 5,200
NSTAR Electric
Regulatory Assets [Line Items]
Amount of regulatory costs not yet approved			61,400			61,400					49,300
Regulatory assets			1,389,000			1,389,000					$ 1,438,200
Other income, net			$ 10,657		$ 14,269	$ 21,743	$ 26,870

REGULATORY ACCOUNTING - Components of Regulatory Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,019,700	$ 3,979,700
Less: Current Portion	379,850	370,230
Total Long-Term Regulatory Liabilities	3,639,792	3,609,475
EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	2,860,700	2,883,000
Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	544,900	521,000
Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	83,800	91,200
Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	333,300	309,000
AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	71,700	70,700
Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	29,200	24,600
Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	96,100	80,200
CL&P
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,265,800	1,231,800
Less: Current Portion	112,414	109,614
Total Long-Term Regulatory Liabilities	1,153,360	1,122,157
CL&P \| EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,028,700	1,031,000
CL&P \| Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	51,000	39,900
CL&P \| Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
CL&P \| Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	110,000	89,500
CL&P \| AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	46,700	47,400
CL&P \| Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
CL&P \| Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	29,400	24,000
NSTAR Electric
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,685,800	1,703,900
Less: Current Portion	170,970	190,620
Total Long-Term Regulatory Liabilities	1,514,845	1,513,279
NSTAR Electric \| EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	1,090,000	1,103,700
NSTAR Electric \| Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	319,400	307,100
NSTAR Electric \| Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	70,900	76,900
NSTAR Electric \| Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	141,900	163,700
NSTAR Electric \| AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	25,000	23,300
NSTAR Electric \| Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
NSTAR Electric \| Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	38,600	29,200
PSNH
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	471,200	483,600
Less: Current Portion	54,183	55,526
Total Long-Term Regulatory Liabilities	416,999	428,069
PSNH \| EDIT due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	395,400	396,400
PSNH \| Cost of Removal
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	21,400	22,100
PSNH \| Benefit Costs
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH \| Regulatory Tracker Mechanisms
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	31,200	48,300
PSNH \| AFUDC - Transmission
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	0	0
PSNH \| Revenue Subject to Refund due to Tax Cuts and Jobs Act
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	19,100	12,600
PSNH \| Other Regulatory Liabilities
Regulatory Liabilities [Line Items]
Total Regulatory Liabilities	$ 4,100	$ 4,200

PROPERTY, PLANT AND EQUIPMENT AND ACCUMULATED DEPRECIATION (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	$ 15,472,100	$ 15,071,100
Distribution - Natural Gas	3,632,900	3,546,200
Transmission - Electric	10,449,500	10,153,900
Distribution - Water	1,664,100	1,639,800
Solar	196,900	164,100
Utility	31,415,500	30,575,100
Other	882,400	778,600
Property, Plant and Equipment, Gross	32,297,900	31,353,700
Less: Accumulated Depreciation
Utility	(7,357,900)	(7,126,200)
Other	(363,100)	(336,700)
Total Accumulated Depreciation	(7,721,000)	(7,462,900)
Property, Plant and Equipment, Net	24,576,900	23,890,800
Construction Work in Progress	1,727,500	1,719,600
Total Property, Plant and Equipment, Net	26,304,446	25,610,428
CL&P
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	6,352,800	6,176,400
Transmission - Electric	4,880,600	4,700,500
Solar	0	0
Property, Plant and Equipment, Gross	11,233,400	10,876,900
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,352,200)	(2,302,600)
Property, Plant and Equipment, Net	8,881,200	8,574,300
Construction Work in Progress	404,400	335,400
Total Property, Plant and Equipment, Net	9,285,633	8,909,701
NSTAR Electric
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	6,921,300	6,756,400
Transmission - Electric	4,148,800	4,065,900
Solar	196,900	164,100
Property, Plant and Equipment, Gross	11,267,000	10,986,400
Less: Accumulated Depreciation
Total Accumulated Depreciation	(2,814,900)	(2,702,000)
Property, Plant and Equipment, Net	8,452,100	8,284,400
Construction Work in Progress	623,700	510,300
Total Property, Plant and Equipment, Net	9,075,789	8,794,700
PSNH
Public Utility, Property, Plant and Equipment [Line Items]
Distribution - Electric	2,238,300	2,178,600
Transmission - Electric	1,415,200	1,338,700
Solar	0	0
Property, Plant and Equipment, Gross	3,653,500	3,517,300
Less: Accumulated Depreciation
Total Accumulated Depreciation	(806,400)	(772,900)
Property, Plant and Equipment, Net	2,847,100	2,744,400
Construction Work in Progress	122,200	135,700
Total Property, Plant and Equipment, Net	$ 2,969,347	$ 2,880,073

DERIVATIVE INSTRUMENTS - Gross Fair Values and Net Amounts of Contracts (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Current Derivative Assets \| CL&P \| Level 3
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	$ 11.1	$ 9.6
Netting	(0.3)	(3.4)
Net Amount Recorded as a Derivative	10.8	6.2
Current Derivative Assets \| Other \| Level 2
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	0.0	1.5
Netting	0.0	(0.9)
Net Amount Recorded as a Derivative	0.0	0.6
Long-term Derivative Assets \| CL&P \| Level 3
Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract]
Commodity Supply and Price Risk Management	71.8	74.2
Netting	(2.2)	(2.3)
Net Amount Recorded as a Derivative	69.6	71.9
Current Derivative Liabilities \| CL&P \| Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(62.1)	(55.1)
Netting	0.0	0.0
Net Amount Recorded as a Derivative	(62.1)	(55.1)
Current Derivative Liabilities \| Other \| Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(2.4)	0.0
Netting	0.0	0.0
Net Amount Recorded as a Derivative	(2.4)	0.0
Long-Term Derivative Liabilities \| CL&P \| Level 3
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(363.7)	(379.5)
Netting	0.0	0.0
Net Amount Recorded as a Derivative	(363.7)	(379.5)
Long-Term Derivative Liabilities \| Other \| Level 2
Current and Long-Term Derivative Liabilities
Commodity Supply and Price Risk Management	(0.1)	0.0
Netting	0.0	0.0
Net Amount Recorded as a Derivative	$ (0.1)	$ 0.0

DERIVATIVE INSTRUMENTS - Narrative (Details) MWh in Millions, MMBTU in Millions, $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019 USD ($) MW	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) MMBTU MWh MW	Jun. 30, 2018 USD ($)	Dec. 31, 2018 MMBTU MW
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts by United Illuminated Company			20.00%
Amount of power to be purchased under capacity-related contract (in MW) \| MW	679		679		787
Amount of natural gas to be purchased under futures contracts \| MMBTU			7.1		12.5
Gains (losses) on deferred as regulatory costs \| $	$ (5.1)	$ 8.6	$ (10.3)	$ (27.5)
Level 3 \| Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts			3.10%
Level 3 \| Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of exit price premiums related to derivative contracts			14.60%
CL&P
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Percentage of costs or benefits borne under capacity-related contracts			80.00%
Amount of energy to be purchased under renewable energy contract (mwh) \| MWh			0.1

DERIVATIVE INSTRUMENTS - Summary of Level 3 Derivative Contracts and Significant Observable Inputs Used (Details) - CL&P - Level 3 - $ / KWmo	Jun. 30, 2019	Dec. 31, 2018
Capacity Prices \| Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	4.30	4.30
Capacity Prices \| Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	7.34	7.44
Forward Reserve \| Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	0.75	0.75
Forward Reserve \| Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative measurement input	1.78	1.78

DERIVATIVE INSTRUMENTS - Changes in the Level 3 Category of Derivative Assets Measured at Fair Value on a Recurring Basis (Details) - CL&P - Level 3 - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	$ (353.1)	$ (386.5)	$ (356.5)	$ (362.3)
Net Realized/Unrealized (Losses)/Gains Included in Regulatory Assets	(2.5)	8.6	(7.8)	(28.2)
Settlements	10.2	8.6	18.9	21.2
Fair Value as of End of Period	$ (345.4)	$ (369.3)	$ (345.4)	$ (369.3)

MARKETABLE SECURITIES - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	$ 45.2		$ 45.2		$ 44.0
Unrealized gains recorded in other income	2.3	$ 0.9	3.3	$ 0.2
CYAPC and YAEC
Debt Securities, Available-for-sale [Line Items]
Available-for-sale equity securities	158.5		158.5		200.0
Marketable securities held in nuclear decommissioning trust	$ 172.4		$ 172.4		$ 143.9

MARKETABLE SECURITIES - Summary of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Amortized Cost	$ 204.3	$ 190.0
Pre-Tax Unrealized Gains	5.4	0.4
Pre-Tax Unrealized Losses	(0.1)	(4.0)
Fair Value	$ 209.6	$ 186.4

MARKETABLE SECURITIES - Contractual Maturities of Available-for-Sale Debt Securities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Amortized Cost
Less than one year	$ 26.9
One to five years	48.8
Six to ten years	38.4
Greater than ten years	90.2
Amortized Cost	204.3	$ 190.0
Fair Value
Less than one year	26.9
One to five years	49.6
Six to ten years	40.0
Greater than ten years	93.1
Fair Value	$ 209.6	$ 186.4

MARKETABLE SECURITIES - Marketable Securities Recorded at Fair Value on a Recurring Basis by Level (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 413.3	$ 430.4
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	224.2	269.9
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	189.1	160.5
Mutual Funds and Equities \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	203.7	244.0
Money Market Funds \| Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	20.5	25.9
U.S. Government Issued Debt Securities (Agency and Treasury) \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	107.0	79.6
Corporate Debt Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	46.1	39.5
Asset-Backed Debt Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	13.4	14.0
Municipal Bonds \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	12.8	19.2
Other Fixed Income Securities \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 9.8	$ 8.2

SHORT-TERM AND LONG-TERM DEBT - Narrative (Details) - USD ($)	6 Months Ended
	Jun. 30, 2019	Apr. 26, 2019	Dec. 31, 2018
Line of Credit Facility [Line Items]
Current portion of long-term debt	$ (779,289,000)		$ (837,319,000)
Long-term debt	13,039,180,000		12,248,743,000
NSTAR Electric
Line of Credit Facility [Line Items]
Current portion of long-term debt	(95,000,000)		0
Long-term debt	3,246,535,000		2,944,846,000
CL&P
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	259,400,000
Current portion of long-term debt	0		(250,000,000)
Long-term debt	3,309,455,000		3,004,016,000
PSNH
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	20,100,000		57,000,000.0
Amount of long-term debt approved for issuance		$ 300,000,000
Current portion of long-term debt	(150,000,000)		(150,000,000)
Long-term debt	951,834,000		655,173,000
HEEC
Line of Credit Facility [Line Items]
Notes payable to Eversource parent	40,300,000
NSTAR Gas \| Senior Notes \| NSTAR Gas 3.74% Series Q First Mortgage Bonds \| Adjustment
Line of Credit Facility [Line Items]
Current portion of long-term debt	(75,000,000)
Long-term debt	75,000,000
Commercial Paper \| NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	650,000,000
Line of Credit
Line of Credit Facility [Line Items]
Amount outstanding under line of credit	0		0
Line of Credit \| NSTAR Electric
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 650,000,000
Debt instrument term	5 years
Line of Credit \| Aquarion
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 100,000,000
Amount outstanding under line of credit	0		$ 0
Eversource Parent \| Commercial Paper
Line of Credit Facility [Line Items]
Maximum borrowing capacity	1,450,000,000
Eversource Parent \| Line of Credit
Line of Credit Facility [Line Items]
Maximum borrowing capacity	$ 1,450,000,000
Debt instrument term	5 years

SHORT-TERM AND LONG-TERM DEBT - Borrowings Outstanding and Available under the Commercial Paper Programs (Details) - Commercial Paper - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Borrowings outstanding	$ 566.0	$ 631.5
Available borrowing capacity	$ 884.0	$ 818.5
Weighted-average interest rate	2.55%	2.77%
NSTAR Electric
Debt Instrument [Line Items]
Borrowings outstanding	$ 163.0	$ 278.5
Available borrowing capacity	$ 487.0	$ 371.5
Weighted-average interest rate	2.42%	2.50%

SHORT-TERM AND LONG-TERM DEBT - Summary of Long-Term Debt Issuance and Repayments (Details) - USD ($) $ in Thousands			1 Months Ended			6 Months Ended
	May 01, 2019	Feb. 01, 2019	Jul. 31, 2019	Jun. 30, 2019	Apr. 30, 2019	Jun. 30, 2019	Jun. 30, 2018	Feb. 01, 2009
Debt Instrument [Line Items]
Repayments						$ (250,437)	$ (860,421)
CL&P
Debt Instrument [Line Items]
Repayments						(250,000)	(300,000)
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Issuances					$ 300,000
Interest rate, stated percentage					4.00%
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds \| Eversource Parent
Debt Instrument [Line Items]
Long-term debt				$ 800,000		800,000
CL&P \| Senior Notes \| 5.50% 2009 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments		$ (250,000)
Interest rate, stated percentage								5.50%
NSTAR Electric \| Senior Notes \| 3.25% 2019 Debentures
Debt Instrument [Line Items]
Issuances	$ 400,000
Interest rate, stated percentage	3.25%
PSNH
Debt Instrument [Line Items]
Repayments						$ 0	$ (110,000)
PSNH \| Senior Notes \| 3.60% 2019 Series T First Mortgage Bonds
Debt Instrument [Line Items]
Issuances				$ 300,000
Interest rate, stated percentage				3.60%		3.60%
Other \| Senior Notes \| NSTAR Gas 3.74% Series Q First Mortgage Bonds \| Subsequent Event
Debt Instrument [Line Items]
Issuances			$ 75,000
Interest rate, stated percentage			3.74%

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Narrative (Details) - PSNH - Rate Reduction Bonds $ in Millions	May 08, 2018 USD ($)
Debt Instrument [Line Items]
Amount of securitized rate reduction bonds issued	$ 635.7
Weighted average interest rate	3.66%

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	$ 4,919,500	$ 5,145,900
Regulatory Liabilities	3,639,792	3,609,475
Accrued Interest (included in Other Current Liabilities)	677,341	823,006
Rate Reduction Bonds - Current Portion	43,210	52,332
Rate Reduction Bonds - Long-Term Portion	561,727	583,331
Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	586,900	608,400
Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	148,800	208,000
Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	54,100	72,100
Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	72,000	3,200
PSNH
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	905,800	929,500
Regulatory Liabilities	416,999	428,069
Accrued Interest (included in Other Current Liabilities)	45,414	64,046
Rate Reduction Bonds - Current Portion	43,210	52,332
Rate Reduction Bonds - Long-Term Portion	561,727	583,331
PSNH \| Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	586,900	608,400
PSNH \| Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	17,700	12,100
PSNH \| Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	35,000	47,500
PSNH \| Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	3,200	3,200
PSNH \| VIE
Condensed Balance Sheet Statements, Captions [Line Items]
Rate Reduction Bonds - Current Portion	43,200	52,300
Rate Reduction Bonds - Long-Term Portion	561,700	583,300
PSNH \| VIE \| Securitized Stranded Costs
Condensed Balance Sheet Statements, Captions [Line Items]
Securitized Stranded Costs (included in Regulatory Assets)	586,900	608,400
PSNH \| VIE \| Other Regulatory Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Regulatory Liabilities	7,900	5,800
Accrued Interest (included in Other Current Liabilities)	8,900	14,400
PSNH \| VIE \| Prepayments and Other Current Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	35,000	47,500
PSNH \| VIE \| Other Long-Term Assets
Condensed Balance Sheet Statements, Captions [Line Items]
Restricted Cash	$ 3,200	$ 3,200

RATE REDUCTION BONDS AND VARIABLE INTEREST ENTITIES - Summary of the Impact of Funding on the Income Statements (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Income Statements, Captions [Line Items]
Interest Expense on RRB Principal (included in Interest Expense)	$ 132,705	$ 126,404	$ 264,438	$ 247,533
PSNH
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	5,857	8,926	19,523	13,961
Interest Expense on RRB Principal (included in Interest Expense)	13,909	14,612	28,276	27,386
PSNH \| VIE \| Rate Reduction Bonds
Condensed Income Statements, Captions [Line Items]
Amortization of RRB Principal (included in Amortization of Regulatory Assets, Net)	10,800	6,800	21,500	6,800
Interest Expense on RRB Principal (included in Interest Expense)	$ 5,300	$ 2,800	$ 10,700	$ 2,800

PENSION BENEFITS AND POSTRETIREMENT BENEFITS OTHER THAN PENSION (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	$ 16.1	$ 20.7	$ 35.4	$ 43.1
Interest Cost	54.8	49.1	109.1	97.8
Expected Return on Pension Plan Assets	(91.7)	(97.9)	(183.8)	(195.8)
Actuarial Loss	35.6	35.7	72.1	71.8
Prior Service Cost/(Credit)	0.3	2.1	0.6	4.1
Total Net Periodic Benefit Expense/(Income)	15.1	9.7	33.4	21.0
PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	1.8	2.5	3.9	5.0
Interest Cost	8.2	6.8	16.3	14.4
Expected Return on Pension Plan Assets	(16.8)	(16.7)	(33.4)	(34.8)
Actuarial Loss	1.6	1.6	4.1	4.4
Prior Service Cost/(Credit)	(5.8)	(5.7)	(11.6)	(11.5)
Total Net Periodic Benefit Expense/(Income)	(11.0)	(11.5)	(20.7)	(22.5)
CL&P \| Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	4.4	5.2	9.2	11.0
Interest Cost	11.4	10.5	23.0	20.9
Expected Return on Pension Plan Assets	(18.1)	(19.4)	(36.9)	(40.2)
Actuarial Loss	6.3	7.1	14.3	14.8
Prior Service Cost/(Credit)	0.0	0.2	0.0	0.6
Total Net Periodic Benefit Expense/(Income)	4.0	3.6	9.6	7.1
Intercompany Allocations	5.8	1.5	13.6	3.0
CL&P \| PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.3	0.4	0.7	0.9
Interest Cost	1.6	1.5	3.1	2.9
Expected Return on Pension Plan Assets	(2.3)	(2.6)	(4.5)	(5.2)
Actuarial Loss	0.3	0.4	0.7	0.8
Prior Service Cost/(Credit)	0.3	0.3	0.5	0.5
Total Net Periodic Benefit Expense/(Income)	0.2	0.0	0.5	(0.1)
Intercompany Allocations	(0.3)	(0.2)	(0.4)	(0.5)
NSTAR Electric \| Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	3.6	4.3	7.5	9.0
Interest Cost	12.3	10.9	24.2	21.7
Expected Return on Pension Plan Assets	(24.2)	(26.6)	(48.6)	(51.8)
Actuarial Loss	11.8	10.1	21.2	20.7
Prior Service Cost/(Credit)	0.0	0.1	0.1	0.1
Total Net Periodic Benefit Expense/(Income)	3.5	(1.2)	4.4	(0.3)
Intercompany Allocations	5.3	1.6	8.4	3.2
NSTAR Electric \| PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.4	0.5	0.9	1.0
Interest Cost	2.4	2.2	4.7	4.4
Expected Return on Pension Plan Assets	(7.5)	(8.1)	(15.1)	(16.2)
Actuarial Loss	0.7	0.4	1.7	1.1
Prior Service Cost/(Credit)	(4.2)	(4.3)	(8.5)	(8.5)
Total Net Periodic Benefit Expense/(Income)	(8.2)	(9.3)	(16.3)	(18.2)
Intercompany Allocations	(0.4)	(0.3)	(0.6)	(0.7)
PSNH \| Pension and SERP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	1.5	2.7	4.1	5.7
Interest Cost	6.0	5.5	12.2	10.9
Expected Return on Pension Plan Assets	(10.1)	(10.8)	(20.4)	(21.8)
Actuarial Loss	2.3	3.3	5.9	6.5
Prior Service Cost/(Credit)	0.0	0.1	0.0	0.2
Total Net Periodic Benefit Expense/(Income)	(0.3)	0.8	1.8	1.5
Intercompany Allocations	0.0	0.5	2.5	1.0
PSNH \| PBOP
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service Cost	0.1	0.3	0.4	0.6
Interest Cost	0.8	0.9	1.7	1.6
Expected Return on Pension Plan Assets	(1.3)	(1.5)	(2.8)	(3.0)
Actuarial Loss	0.0	0.2	0.2	0.4
Prior Service Cost/(Credit)	0.1	0.1	0.2	0.3
Total Net Periodic Benefit Expense/(Income)	(0.3)	0.0	(0.3)	(0.1)
Intercompany Allocations	$ (0.1)	$ (0.1)	$ (0.2)	$ (0.2)

COMMITMENTS AND CONTINGENCIES - Environmental Sites and Related Reserves (Details) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($) site	Dec. 31, 2018 USD ($) site
Site Contingency [Line Items]
Number of Sites \| site	58	60
Reserve \| $	$ 71.6	$ 64.7
CL&P
Site Contingency [Line Items]
Number of Sites \| site	15	15
Reserve \| $	$ 5.8	$ 5.4
NSTAR Electric
Site Contingency [Line Items]
Number of Sites \| site	15	16
Reserve \| $	$ 10.5	$ 10.9
PSNH
Site Contingency [Line Items]
Number of Sites \| site	9	9
Reserve \| $	$ 5.4	$ 5.4

COMMITMENTS AND CONTINGENCIES - Environmental Matters (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Site Contingency [Line Items]
Reserve balance	$ 71.6	$ 64.7
MGP Sites
Site Contingency [Line Items]
Reserve balance	$ 57.1	$ 50.1

COMMITMENTS AND CONTINGENCIES - Long-Term Contractual Arrangements (Details) - Milestone Nuclear Power Station MWh in Millions	Mar. 15, 2019 megawatt	Dec. 28, 2018 MWh
Long-term Purchase Commitment [Line Items]
Annual purchase requirement (in MWh) \| MWh		9
Percent of the facility's output required to be purchased	50.00%
Nameplate capacity (in megawatts) \| megawatt	2,112
CL&P
Long-term Purchase Commitment [Line Items]
Contract term	10 years	10 years
Percent of the facility's output required to be purchased	40.00%
UI
Long-term Purchase Commitment [Line Items]
Contract term	10 years	10 years

COMMITMENTS AND CONTINGENCIES - Guarantees and Indemnifications (Details)	Jun. 30, 2019 USD ($)
Guarantee of Financial Obligations of NPT
Guarantor Obligations [Line Items]
Maximum exposure (up to)	$ 25,000,000
Guarantee of NPT Letters of Credit
Guarantor Obligations [Line Items]
Maximum exposure (up to)	$ 14,000,000

COMMITMENTS AND CONTINGENCIES - Summary of Exposure to Guaruantees and Indemnifications (Details) $ in Millions	Jun. 30, 2019 USD ($)
Eversource Investment LLC - Declining Balance Guarantee for North East Offshore
Loss Contingencies [Line Items]
Maximum exposure	$ 113.9
Various - Surety Bonds
Loss Contingencies [Line Items]
Maximum exposure	34.0
Rocky River Realty Company and Eversource Service - Lease Payments for Real Estate
Loss Contingencies [Line Items]
Maximum exposure	7.1
Bay State Wind LLC - Real Estate Purchase
Loss Contingencies [Line Items]
Maximum exposure	$ 2.5

COMMITMENTS AND CONTINGENCIES - Spent Nuclear Fuel Obligations - Yankee Companies (Details) - USD ($) $ in Millions				1 Months Ended
	Jun. 12, 2019	Feb. 21, 2019	May 22, 2017	Jul. 31, 2019
Loss Contingencies [Line Items]
Damages awarded	$ 0.5
Remaining damages sought		$ 1.0
Subsequent Event
Loss Contingencies [Line Items]
Damages paid				$ 0.5
CYAPC, YAEC, and MYAPC
Loss Contingencies [Line Items]
Damages sought			$ 104.4
Damages awarded		103.2
CYAPC
Loss Contingencies [Line Items]
Damages awarded		40.7
YAEC
Loss Contingencies [Line Items]
Damages awarded		28.1
MYAPC
Loss Contingencies [Line Items]
Damages awarded		$ 34.4

COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints (Details) - USD ($) $ in Millions			6 Months Ended	36 Months Ended
	Apr. 29, 2016	Oct. 16, 2014	Jun. 30, 2019	Oct. 15, 2014
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			10.41%
Percentage of incentive cap on total ROE			13.08%
Minimum
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			9.60%
Maximum
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified			10.99%
FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Base ROE subsequently authorized			11.14%
FERC ROE First, Second and Third Complaints \| Minimum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project				11.14%
FERC ROE First, Second and Third Complaints \| Maximum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project				13.10%
FERC ROE Complaints
Loss Contingencies [Line Items]
Period of complaint			15 months
Basis point change			0.10%
Estimate of possible loss for each 10 basis point change to base ROE			$ 3.0
FERC ROE Fourth Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period	10.57%
Maximum percentage cap of ROE for incentive projects	11.74%
FERC ROE First Complaint
Loss Contingencies [Line Items]
Base ROE subsequently authorized		10.57%
Percentage of maximum ROE for any incentive project		11.74%
Amounts associated with first complaint refunded			38.9
FERC ROE First Complaint \| CL&P
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			22.4
FERC ROE First Complaint \| NSTAR Electric
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			13.7
FERC ROE First Complaint \| PSNH
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded			$ 2.8
FERC ROE Second Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period			10.57%
Percentage of maximum ROE for any incentive project			11.74%
Loss contingency, estimate of possible earnings impact			$ 39.1
FERC ROE Second Complaint \| CL&P
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			21.4
FERC ROE Second Complaint \| NSTAR Electric
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			14.6
FERC ROE Second Complaint \| PSNH
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact			$ 3.1

COMMITMENTS AND CONTINGENCIES - Eversource and NSTAR Electric Boston Harbor Civil Action (Details) $ in Millions		12 Months Ended
	Jul. 15, 2016 USD ($) kV	Dec. 31, 2018 USD ($)
Loss Contingencies [Line Items]
Amount of capacity required for installation of distribution cable (in kV) \| kV	115
NSTAR Electric
Loss Contingencies [Line Items]
Base rate credit for new cable \| $	$ 17.5	$ 17.5

LEASES - Narrative (Details)	6 Months Ended
LEASES - Narrative (Details)	Jun. 30, 2019
Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
CL&P \| Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
CL&P \| Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
NSTAR Electric \| Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
NSTAR Electric \| Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years
PSNH \| Minimum
Lessee, Lease, Description [Line Items]
Renewal period	1 year
PSNH \| Maximum
Lessee, Lease, Description [Line Items]
Renewal period	20 years

LEASES - Components of Lease Cost (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019
Financing Lease Cost:
Amortization of Right-of-use-Assets	$ 0.4	$ 0.7
Interest on Lease Liabilities	0.3	0.7
Total Finance Lease Cost	0.7	1.4
Operating Lease Cost	2.9	5.9
Variable Lease Cost	15.7	31.1
Total Lease Cost	19.3	38.4
CL&P
Financing Lease Cost:
Amortization of Right-of-use-Assets	0.2	0.4
Interest on Lease Liabilities	0.1	0.3
Total Finance Lease Cost	0.3	0.7
Operating Lease Cost	0.1	0.1
Variable Lease Cost	3.1	6.5
Total Lease Cost	3.5	7.3
NSTAR Electric
Financing Lease Cost:
Amortization of Right-of-use-Assets	0.0	0.1
Interest on Lease Liabilities	0.2	0.3
Total Finance Lease Cost	0.2	0.4
Operating Lease Cost	0.5	0.9
Variable Lease Cost	0.0	0.0
Total Lease Cost	0.7	1.3
PSNH
Financing Lease Cost:
Amortization of Right-of-use-Assets	0.0	0.0
Interest on Lease Liabilities	0.0	0.0
Total Finance Lease Cost	0.0	0.0
Operating Lease Cost	0.0	0.0
Variable Lease Cost	12.6	24.6
Total Lease Cost	$ 12.6	$ 24.6

LEASES - Supplemental Balance Sheet Information Related to Leases (Details) $ in Millions	Jun. 30, 2019 USD ($)
Operating Leases:
Operating Lease Right-of-use-Assets, Net	$ 54.6
Operating Lease Liabilities - Current Portion	8.8
Operating Lease Liabilities - Long-Term	45.8
Total Operating Lease Liabilities	54.6
Finance Leases:
Finance Lease Right-of-use-Assets, Net	9.4
Finance Lease Liabilities - Current Portion	2.3
Finance Lease Liabilities - Long-Term	9.3
Total Finance Lease Liabilities	11.6
CL&P
Operating Leases:
Operating Lease Right-of-use-Assets, Net	0.6
Operating Lease Liabilities - Current Portion	0.2
Operating Lease Liabilities - Long-Term	0.4
Total Operating Lease Liabilities	0.6
Finance Leases:
Finance Lease Right-of-use-Assets, Net	2.6
Finance Lease Liabilities - Current Portion	1.5
Finance Lease Liabilities - Long-Term	2.3
Total Finance Lease Liabilities	3.8
NSTAR Electric
Operating Leases:
Operating Lease Right-of-use-Assets, Net	24.4
Operating Lease Liabilities - Current Portion	0.5
Operating Lease Liabilities - Long-Term	23.9
Total Operating Lease Liabilities	24.4
Finance Leases:
Finance Lease Right-of-use-Assets, Net	3.4
Finance Lease Liabilities - Current Portion	0.0
Finance Lease Liabilities - Long-Term	4.4
Total Finance Lease Liabilities	4.4
PSNH
Operating Leases:
Operating Lease Right-of-use-Assets, Net	0.8
Operating Lease Liabilities - Current Portion	0.2
Operating Lease Liabilities - Long-Term	0.6
Total Operating Lease Liabilities	0.8
Finance Leases:
Finance Lease Right-of-use-Assets, Net	0.9
Finance Lease Liabilities - Current Portion	0.1
Finance Lease Liabilities - Long-Term	0.8
Total Finance Lease Liabilities	$ 0.9

LEASES - Other Information Related to Leases (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Weighted-Average Remaining Lease Term:
Operating Leases	12 years	12 years
Financing Leases	11 years	11 years
Weighted-Average Discount Rate:
Operating Leases	3.90%	3.90%
Financing Leases	4.30%	4.30%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 3.0	$ 5.9
Operating Cash Flows from Finance Leases	0.3	0.6
Financing Cash Flows from Finance Leases	0.5	0.9
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.4	1.7
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 1.3	$ 1.3
CL&P
Weighted-Average Remaining Lease Term:
Operating Leases	4 years	4 years
Financing Leases	2 years	2 years
Weighted-Average Discount Rate:
Operating Leases	2.70%	2.70%
Financing Leases	10.50%	10.50%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.1	$ 0.1
Operating Cash Flows from Finance Leases	0.1	0.3
Financing Cash Flows from Finance Leases	0.4	0.7
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.2	0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0.0	$ 0.0
NSTAR Electric
Weighted-Average Remaining Lease Term:
Operating Leases	21 years	21 years
Financing Leases	23 years	23 years
Weighted-Average Discount Rate:
Operating Leases	4.10%	4.10%
Financing Leases	2.90%	2.90%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.5	$ 0.8
Operating Cash Flows from Finance Leases	0.1	0.3
Financing Cash Flows from Finance Leases	0.0	0.0
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.0	0.0
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0.0	$ 0.0
PSNH
Weighted-Average Remaining Lease Term:
Operating Leases	8 years	8 years
Financing Leases	9 years	9 years
Weighted-Average Discount Rate:
Operating Leases	3.60%	3.60%
Financing Leases	3.50%	3.50%
Cash Paid for Amounts Included in the Measurement of Lease Liabilities:
Operating Cash Flows from Operating Leases	$ 0.0	$ 0.0
Operating Cash Flows from Finance Leases	0.0	0.0
Financing Cash Flows from Finance Leases	0.0	0.0
Supplemental Non-Cash Information on Lease Liabilities:
Right-of-use-Assets Obtained in Exchange for New Operating Lease Liabilities	0.2	0.2
Right-of-use-Assets Obtained in Exchange for New Finance Lease Liabilities	$ 0.0	$ 0.0

LEASES - Future Minimum Lease Payments under Long-Term Leases (Details) $ in Millions	Jun. 30, 2019 USD ($)
Operating Leases
July 1, 2019 through December 31, 2019	$ 5.7
Year Ending December 31,
2020	10.3
2021	9.2
2022	7.5
2023	4.9
2024	2.9
Thereafter	29.2
Future lease payments	69.7
Less amount representing interest	15.1
Present value of future minimum lease payments	54.6
Finance Leases
July 1, 2019 through December 31, 2019	1.7
Year Ending December 31,
2020	3.4
2021	2.9
2022	1.5
2023	0.7
2024	0.7
Thereafter	13.2
Future lease payments	24.1
Less amount representing interest	12.5
Present value of future minimum lease payments	11.6
CL&P
Operating Leases
July 1, 2019 through December 31, 2019	0.3
Year Ending December 31,
2020	0.2
2021	0.1
2022	0.0
2023	0.0
2024	0.0
Thereafter	0.1
Future lease payments	0.7
Less amount representing interest	0.1
Present value of future minimum lease payments	0.6
Finance Leases
July 1, 2019 through December 31, 2019	1.0
Year Ending December 31,
2020	2.0
2021	1.5
2022	0.0
2023	0.0
2024	0.0
Thereafter	0.0
Future lease payments	4.5
Less amount representing interest	0.7
Present value of future minimum lease payments	3.8
NSTAR Electric
Operating Leases
July 1, 2019 through December 31, 2019	0.8
Year Ending December 31,
2020	1.6
2021	1.6
2022	1.6
2023	1.6
2024	1.7
Thereafter	28.9
Future lease payments	37.8
Less amount representing interest	13.4
Present value of future minimum lease payments	24.4
Finance Leases
July 1, 2019 through December 31, 2019	0.3
Year Ending December 31,
2020	0.5
2021	0.5
2022	0.6
2023	0.6
2024	0.6
Thereafter	12.8
Future lease payments	15.9
Less amount representing interest	11.5
Present value of future minimum lease payments	4.4
PSNH
Operating Leases
July 1, 2019 through December 31, 2019	0.2
Year Ending December 31,
2020	0.2
2021	0.2
2022	0.1
2023	0.1
2024	0.0
Thereafter	0.2
Future lease payments	1.0
Less amount representing interest	0.2
Present value of future minimum lease payments	0.8
Finance Leases
July 1, 2019 through December 31, 2019	0.1
Year Ending December 31,
2020	0.1
2021	0.1
2022	0.1
2023	0.1
2024	0.1
Thereafter	0.4
Future lease payments	1.0
Less amount representing interest	0.1
Present value of future minimum lease payments	$ 0.9

LEASES - Future Minimum Rental Payments under Operating Leases (Details) $ in Millions	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
2019	$ 11.5
2020	9.8
2021	8.7
2022	7.2
2023	4.7
Thereafter	32.7
Future minimum lease payments	74.6
CL&P
Operating Leased Assets [Line Items]
2019	1.5
2020	1.4
2021	1.2
2022	1.1
2023	0.5
Thereafter	0.2
Future minimum lease payments	5.9
NSTAR Electric
Operating Leased Assets [Line Items]
2019	7.2
2020	6.0
2021	5.3
2022	4.4
2023	3.1
Thereafter	29.5
Future minimum lease payments	55.5
PSNH
Operating Leased Assets [Line Items]
2019	0.5
2020	0.4
2021	0.4
2022	0.4
2023	0.2
Thereafter	0.3
Future minimum lease payments	$ 2.2

LEASES - Future Minimum Rental Payments under Capital Leases (Details) $ in Millions	Dec. 31, 2018 USD ($)
Capital Leased Assets [Line Items]
2019	$ 3.4
2020	3.4
2021	2.9
2022	1.5
2023	0.7
Thereafter	13.9
Future minimum lease payments	25.8
Less amount representing interest	13.8
Present value of future minimum lease payments	12.0
CL&P
Capital Leased Assets [Line Items]
2019	2.0
2020	2.0
2021	1.5
2022	0.0
2023	0.0
Thereafter	0.0
Future minimum lease payments	5.5
Less amount representing interest	1.0
Present value of future minimum lease payments	4.5
NSTAR Electric
Capital Leased Assets [Line Items]
2019	0.5
2020	0.5
2021	0.5
2022	0.6
2023	0.6
Thereafter	13.4
Future minimum lease payments	16.1
Less amount representing interest	12.4
Present value of future minimum lease payments	3.7
PSNH
Capital Leased Assets [Line Items]
2019	0.1
2020	0.1
2021	0.1
2022	0.1
2023	0.1
Thereafter	0.5
Future minimum lease payments	1.0
Less amount representing interest	0.1
Present value of future minimum lease payments	$ 0.9

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	$ 155,570	$ 155,570
Rate Reduction Bonds	561,727	583,331
Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	155,600	155,600
Long-Term Debt	13,818,500	13,086,100
Rate Reduction Bonds	604,900	635,700
Fair Value \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	161,000	156,800
Long-Term Debt	14,639,400	13,154,900
Rate Reduction Bonds	642,200	645,800
CL&P
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	116,200	116,200
CL&P \| Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	116,200	116,200
Long-Term Debt	3,309,500	3,254,000
Rate Reduction Bonds	0	0
CL&P \| Fair Value \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	117,400	113,800
Long-Term Debt	3,724,900	3,429,200
Rate Reduction Bonds	0	0
NSTAR Electric
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	43,000	43,000
NSTAR Electric \| Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	43,000	43,000
Long-Term Debt	3,341,500	2,944,800
Rate Reduction Bonds	0	0
NSTAR Electric \| Fair Value \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	43,600	43,000
Long-Term Debt	3,599,600	3,024,100
Rate Reduction Bonds	0	0
PSNH
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Rate Reduction Bonds	561,727	583,331
PSNH \| Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-Term Debt	1,101,800	805,200
Rate Reduction Bonds	604,900	635,700
PSNH \| Fair Value \| Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Preferred Stock Not Subject to Mandatory Redemption	0	0
Long-Term Debt	1,145,300	819,500
Rate Reduction Bonds	$ 642,200	$ 645,800

ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications					$ 3,700	$ 2,000
Amounts Reclassified from AOCI					2,700	3,400
Other Comprehensive Income, Net of Tax	$ 4,163	$ 2,196	$ 2,142	$ 3,273	6,359	5,415
Total
AOCI Attributable to Parent [Roll Forward]
Balance		(60,000)		(66,400)	(60,000)	(66,400)
Other Comprehensive Income, Net of Tax	4,163	2,196	2,142	3,273
Balance	(53,600)		(61,000)		(53,600)	(61,000)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance		(4,400)		(6,200)	(4,400)	(6,200)
OCI Before Reclassifications					0	0
Amounts Reclassified from AOCI					600	1,200
Other Comprehensive Income, Net of Tax					600	1,200
Balance	(3,800)		(5,000)		(3,800)	(5,000)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance		(500)		0	(500)	0
OCI Before Reclassifications					1,100	(600)
Amounts Reclassified from AOCI					0	0
Other Comprehensive Income, Net of Tax					1,100	(600)
Balance	600		(600)		600	(600)
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Balance		$ (55,100)		$ (60,200)	(55,100)	(60,200)
OCI Before Reclassifications					2,600	2,600
Amounts Reclassified from AOCI					2,100	2,200
Other Comprehensive Income, Net of Tax					4,700	4,800
Balance	$ (50,400)		$ (55,400)		$ (50,400)	$ (55,400)

COMMON SHARES - Common Shares Authorized and Issued (Details) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Per value (in dollars per share)	$ 5
Authorized (in shares)	380,000,000	380,000,000
Issued (in shares)	339,858,402	333,878,402
CL&P
Class of Stock [Line Items]
Per value (in dollars per share)	$ 10
Authorized (in shares)	24,500,000	24,500,000
Issued (in shares)	6,035,205	6,035,205
NSTAR Electric
Class of Stock [Line Items]
Per value (in dollars per share)	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	200	200
PSNH
Class of Stock [Line Items]
Per value (in dollars per share)	$ 1
Authorized (in shares)	100,000,000	100,000,000
Issued (in shares)	301	301

COMMON SHARES - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended
	Jun. 04, 2019	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Equity [Abstract]
Equity offering (in shares)	17,940,000
Common shares issued directly by the Company (in shares)	5,980,000
Common shares issuable pursuant to forward sale agreement (in shares)	11,960,000
Net proceeds from common shares issued directly by the Company	$ 426,900	$ 426,902	$ 0
Forward sale price (in dollars per share)	$ 71.48
Amount that would have been required to be paid if net settled		$ 50,200
Shares that would have been required to be delivered if net settled (in shares)		662,694
Treasury stock (in shares)		16,283,963		16,992,594
Common stock outstanding (in shares)		323,574,439		316,885,808

COMMON SHAREHOLDERS' EQUITY AND NONCONTROLLING INTERESTS (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Equity [Abstract]
Dividends on preferred stock	$ 1,880	$ 1,880	$ 1,880	$ 1,880	$ 3,800	$ 3,800
Noncontrolling interest attributed to preferred stock of subsidiaries	$ 155,570				$ 155,570		$ 155,570

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net Income Attributable to Common Shareholders	$ 31,454	$ 242,767	$ 340,132	$ 512,313
Weighted Average Common Shares Outstanding:
Basic (in shares)	319,664,998	317,344,596	318,644,796	317,370,825
Dilutive Effect of:
Share-Based Compensation Awards and Other (in shares)	645,450	540,591	668,470	568,269
Equity Forward Sale Agreement (in shares)	78,042	0	39,021	0
Dilutive Effect (in shares)	723,492	540,591	707,491	568,269
Diluted (in shares)	320,388,490	317,885,187	319,352,287	317,939,094
Basic and Diluted EPS (in dollars per share)	$ 0.10	$ 0.76	$ 1.07	$ 1.61

REVENUES (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
REVENUES (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	$ 1,868,200	$ 1,860,600	$ 4,265,600	$ 4,138,900
Alternative Revenue Programs	10,100	(11,900)	24,800	(5,400)
Other Revenues	6,200	5,200	9,900	8,300
Operating Revenues	1,884,495	1,853,856	4,300,287	4,141,818
Lease revenue	1,100		2,200
Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	938,800	930,800	2,257,900	2,201,300
Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	697,400	705,700	1,506,900	1,466,000
Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	103,100	110,600	214,500	220,100
Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,739,300	1,747,100	3,979,300	3,887,400
Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	56,100	55,400	123,700	120,500
Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	54,700	47,200	128,800	124,300
Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	20,300	22,200	38,000	43,200
Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(2,200)	(11,300)	(4,200)	(36,500)
Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers
Operating Revenues
Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers
Other
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	250,800	237,000	509,000	467,900
Alternative Revenue Programs	0	0	0	0
Other Revenues	0	0	0	0
Operating Revenues	250,800	237,000	509,000	467,900
Other \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Other \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Other \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Other \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Other \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,700	12,600	28,300	22,700
Other \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Other \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	236,100	224,400	480,700	445,200
Other \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Eliminations
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(480,300)	(497,500)	(1,000,400)	(980,100)
Alternative Revenue Programs	(58,800)	(2,900)	(69,800)	7,700
Other Revenues	0	0	0	0
Operating Revenues	(539,100)	(500,400)	(1,070,200)	(972,400)
Eliminations \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Eliminations \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(900)	(2,000)	(2,000)	(2,100)
Eliminations \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(2,800)	(2,400)	(5,500)	(5,000)
Eliminations \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,700)	(4,400)	(7,500)	(7,100)
Eliminations \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(239,800)	(268,000)	(510,700)	(526,700)
Eliminations \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Eliminations \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(236,800)	(225,100)	(482,200)	(446,300)
Eliminations \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Distribution \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,550,500	1,550,100	3,379,400	3,293,500
Alternative Revenue Programs	6,300	(14,400)	8,400	(5,700)
Other Revenues	5,000	4,200	7,800	6,700
Operating Revenues	1,561,800	1,539,900	3,395,600	3,294,500
Electric Distribution \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	805,000	794,400	1,838,300	1,788,700
Electric Distribution \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	612,800	622,000	1,265,300	1,233,400
Electric Distribution \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	81,300	88,400	163,400	169,900
Electric Distribution \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,499,100	1,504,800	3,267,000	3,192,000
Electric Distribution \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Distribution \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	39,400	34,200	90,800	92,700
Electric Distribution \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	15,100	18,400	27,700	35,300
Electric Distribution \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,100)	(7,300)	(6,100)	(26,500)
Natural Gas Distribution \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	209,500	205,600	667,400	631,700
Alternative Revenue Programs	(2,700)	100	7,700	(1,700)
Other Revenues	900	800	1,500	1,400
Operating Revenues	207,700	206,500	676,600	631,400
Natural Gas Distribution \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	100,200	104,100	359,100	352,900
Natural Gas Distribution \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	69,500	70,000	213,300	204,700
Natural Gas Distribution \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	23,500	23,500	54,400	53,100
Natural Gas Distribution \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	193,200	197,600	626,800	610,700
Natural Gas Distribution \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Natural Gas Distribution \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	14,400	12,100	36,100	29,900
Natural Gas Distribution \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	400	(600)	1,400	(900)
Natural Gas Distribution \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,500	(3,500)	3,100	(8,000)
Electric Transmission \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	284,900	314,000	613,000	630,700
Alternative Revenue Programs	64,600	3,400	77,000	(8,300)
Other Revenues	100	0	100	0
Operating Revenues	349,600	317,400	690,100	622,400
Electric Transmission \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Transmission \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Transmission \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Transmission \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Transmission \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	281,200	310,800	606,100	624,500
Electric Transmission \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Electric Transmission \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	3,700	3,200	6,900	6,200
Electric Transmission \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Water Distribution \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	52,800	51,400	97,200	95,200
Alternative Revenue Programs	700	1,900	1,500	2,600
Other Revenues	200	200	500	200
Operating Revenues	53,700	53,500	99,200	98,000
Water Distribution \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	33,600	32,300	60,500	59,700
Water Distribution \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	16,000	15,700	30,300	30,000
Water Distribution \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,100	1,100	2,200	2,100
Water Distribution \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	50,700	49,100	93,000	91,800
Water Distribution \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	0
Water Distribution \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	900	900	1,900	1,700
Water Distribution \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	1,800	1,900	3,500	3,700
Water Distribution \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(600)	(500)	(1,200)	(2,000)
CL&P
Disaggregation of Revenue [Line Items]
Operating Revenues	740,846	694,892	1,590,092	1,479,875
Lease revenue	300		500
CL&P \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	798,400	798,900	1,757,600	1,697,100
Alternative Revenue Programs	55,100	1,000	60,900	(4,100)
Other Revenues	2,700	2,400	3,700	3,300
CL&P \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	402,800	387,100	913,400	870,400
CL&P \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	224,700	220,700	461,300	443,200
CL&P \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	33,800	36,500	68,400	72,300
CL&P \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	661,300	644,300	1,443,100	1,385,900
CL&P \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	115,900	139,900	270,700	290,600
CL&P \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	12,100	10,600	25,800	21,000
CL&P \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	9,100	8,300	18,000	16,200
CL&P \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	(4,200)	0	(16,600)
CL&P \| Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(115,400)	(107,400)	(232,100)	(216,400)
NSTAR Electric
Disaggregation of Revenue [Line Items]
Operating Revenues	681,893	690,737	1,479,505	1,460,865
Lease revenue	700		1,300
NSTAR Electric \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	777,800	792,500	1,665,100	1,648,000
Alternative Revenue Programs	2,100	(6,900)	9,300	(200)
Other Revenues	1,900	1,600	3,400	2,700
NSTAR Electric \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	282,300	292,500	653,200	656,700
NSTAR Electric \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	315,800	325,500	652,300	640,000
NSTAR Electric \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	28,900	30,900	57,800	59,000
NSTAR Electric \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	627,000	648,900	1,363,300	1,355,700
NSTAR Electric \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	127,500	120,900	250,100	239,500
NSTAR Electric \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	17,200	13,400	41,600	38,200
NSTAR Electric \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	6,100	9,300	10,100	18,300
NSTAR Electric \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	0	0	0	(3,700)
NSTAR Electric \| Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	(99,900)	(96,500)	(198,300)	(189,600)
PSNH
Disaggregation of Revenue [Line Items]
Operating Revenues	240,900	235,146	517,335	502,497
PSNH \| Operating Segments
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	260,200	273,800	571,900	581,800
Alternative Revenue Programs	13,700	(5,000)	15,200	(9,600)
Other Revenues	500	200	800	600
PSNH \| Operating Segments \| Residential
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	119,900	114,800	271,700	261,600
PSNH \| Operating Segments \| Commercial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	72,700	76,200	152,600	151,100
PSNH \| Operating Segments \| Industrial
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	18,600	21,000	37,200	38,600
PSNH \| Operating Segments \| Total Retail Tariff Sale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	211,200	212,000	461,500	451,300
PSNH \| Operating Segments \| Transmission Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	37,800	50,100	85,300	94,300
PSNH \| Operating Segments \| Wholesale Revenue
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	10,100	10,900	23,400	34,900
PSNH \| Operating Segments \| Other Revenues from Contracts with Customers
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	4,200	3,900	7,800	7,500
PSNH \| Operating Segments \| Reserve for Revenues Subject to Refund
Disaggregation of Revenue [Line Items]
Revenues from Contracts with Customers	(3,100)	(3,100)	(6,100)	(6,200)
PSNH \| Eliminations
Disaggregation of Revenue [Line Items]
Operating Revenues	$ (33,500)	$ (33,900)	$ (70,600)	$ (70,300)

SEGMENT INFORMATION - Narrative (Details) $ in Millions	6 Months Ended
SEGMENT INFORMATION - Narrative (Details) $ in Millions	Jun. 30, 2019 USD ($) segment company
Segment Reporting Information [Line Items]
Number of companies that transmit hydro electricity imported from The Hydro-Quebec System in Canada \| company	2
CL&P
Segment Reporting Information [Line Items]
Number of reportable segments	1
NSTAR Electric
Segment Reporting Information [Line Items]
Number of reportable segments	1
PSNH
Segment Reporting Information [Line Items]
Number of reportable segments	1
Affiliated Entity
Segment Reporting Information [Line Items]
Affiliate transaction costs classified as Purchased Power, Fuel and Transmission Costs \| $	$ 62.5

SEGMENT INFORMATION - Summary of Segment Information and Segmented Total Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Operating Revenues	$ 1,884,495	$ 1,853,856	$ 4,300,287	$ 4,141,818
Depreciation and Amortization	(258,000)	(235,300)	(544,000)	(484,800)
Impairment of Northern Pass Transmission	(239,644)	0	(239,644)	0
Other Operating Expenses	(1,235,900)	(1,227,200)	(2,871,000)	(2,823,100)
Operating Income/(Loss)	150,988	391,354	645,688	833,886
Interest Expense	(132,705)	(126,404)	(264,438)	(247,533)
Other Income/(Loss), Net	45,866	50,149	76,850	83,938
Net Income Attributable to Common Shareholders	31,454	242,767	340,132	512,313
Cash Flows Used for Investments in Plant			1,377,753	1,251,678
Assets	38,995,906		38,995,906		$ 38,241,256
Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues
Other
Segment Reporting Information [Line Items]
Operating Revenues	250,800	237,000	509,000	467,900
Depreciation and Amortization	(14,700)	(11,900)	(28,300)	(23,900)
Impairment of Northern Pass Transmission	0		0
Other Operating Expenses	(218,400)	(211,700)	(444,000)	(416,300)
Operating Income/(Loss)	17,700	13,400	36,700	27,700
Interest Expense	(44,500)	(32,300)	(88,600)	(64,300)
Other Income/(Loss), Net	(114,900)	302,000	316,800	662,100
Net Income Attributable to Common Shareholders	(145,600)	288,800	262,000	634,800
Cash Flows Used for Investments in Plant			103,200	77,100
Assets	18,550,400		18,550,400		17,874,200
Eliminations
Segment Reporting Information [Line Items]
Operating Revenues	(539,100)	(500,400)	(1,070,200)	(972,400)
Depreciation and Amortization	600	600	1,100	1,100
Impairment of Northern Pass Transmission	0		0
Other Operating Expenses	538,700	501,400	1,069,800	973,300
Operating Income/(Loss)	200	1,600	700	2,000
Interest Expense	13,600	8,000	26,100	15,400
Other Income/(Loss), Net	139,100	(281,800)	(288,500)	(637,000)
Net Income Attributable to Common Shareholders	152,900	(272,200)	(261,700)	(619,600)
Cash Flows Used for Investments in Plant			0	0
Assets	(18,004,800)		(18,004,800)		(17,464,900)
Electric Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	1,561,800	1,539,900	3,395,600	3,294,500
Depreciation and Amortization	(150,100)	(135,500)	(329,300)	(279,900)
Impairment of Northern Pass Transmission	0		0
Other Operating Expenses	(1,243,000)	(1,233,000)	(2,718,600)	(2,676,500)
Operating Income/(Loss)	168,700	171,400	347,700	338,100
Interest Expense	(50,800)	(52,100)	(100,000)	(99,500)
Other Income/(Loss), Net	12,200	19,000	30,400	38,600
Net Income Attributable to Common Shareholders	105,400	101,300	225,400	205,500
Cash Flows Used for Investments in Plant			571,300	475,600
Assets	21,628,800		21,628,800		21,389,100
Natural Gas Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	207,700	206,500	676,600	631,400
Depreciation and Amortization	(19,500)	(19,300)	(39,900)	(45,700)
Impairment of Northern Pass Transmission	0		0
Other Operating Expenses	(179,800)	(170,600)	(521,100)	(483,200)
Operating Income/(Loss)	8,400	16,600	115,600	102,500
Interest Expense	(11,900)	(11,400)	(23,700)	(22,500)
Other Income/(Loss), Net	700	1,600	1,000	3,500
Net Income Attributable to Common Shareholders	(1,800)	5,000	74,700	62,800
Cash Flows Used for Investments in Plant			202,700	150,300
Assets	4,031,300		4,031,300		3,904,900
Electric Transmission \| Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	349,600	317,400	690,100	622,400
Depreciation and Amortization	(62,300)	(57,000)	(123,700)	(113,500)
Impairment of Northern Pass Transmission	(239,600)		(239,600)
Other Operating Expenses	(108,400)	(88,800)	(207,200)	(172,000)
Operating Income/(Loss)	(60,700)	171,600	119,600	336,900
Interest Expense	(30,500)	(30,000)	(61,000)	(59,700)
Other Income/(Loss), Net	8,700	9,900	16,800	17,800
Net Income Attributable to Common Shareholders	(87,400)	112,700	30,900	220,100
Cash Flows Used for Investments in Plant			449,200	508,500
Assets	10,499,700		10,499,700		10,285,000
Water Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Operating Revenues	53,700	53,500	99,200	98,000
Depreciation and Amortization	(12,000)	(12,200)	(23,900)	(22,900)
Impairment of Northern Pass Transmission	0		0
Other Operating Expenses	(25,000)	(24,500)	(49,900)	(48,400)
Operating Income/(Loss)	16,700	16,800	25,400	26,700
Interest Expense	(8,600)	(8,600)	(17,200)	(16,900)
Other Income/(Loss), Net	100	(600)	400	(1,100)
Net Income Attributable to Common Shareholders	8,000	$ 7,200	8,800	8,700
Cash Flows Used for Investments in Plant			51,400	$ 40,200
Assets	$ 2,290,500		$ 2,290,500		$ 2,253,000