UNION ELECTRIC CO, 10-Q filed on 8/5/2016
Quarterly Report
Document and Entity Information
6 Months Ended
Jun. 30, 2016
Jul. 29, 2016
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Jun. 30, 2016 
 
Document Fiscal Year Focus
2016 
 
Document Fiscal Period Focus
Q2 
 
Trading Symbol
AEE 
 
Entity Registrant Name
AMEREN CORP 
 
Entity Central Index Key
0001002910 
 
Current Fiscal Year End Date
--12-31 
 
Entity Filer Category
Large Accelerated Filer 
 
Entity Common Stock, Shares Outstanding
 
242,634,798 
Union Electric Company
 
 
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Jun. 30, 2016 
 
Document Fiscal Year Focus
2016 
 
Document Fiscal Period Focus
Q2 
 
Entity Registrant Name
UNION ELECTRIC CO 
 
Entity Central Index Key
0000100826 
 
Current Fiscal Year End Date
--12-31 
 
Entity Filer Category
Non-accelerated Filer 
 
Entity Common Stock, Shares Outstanding
 
102,123,834 
Ameren Illinois Company
 
 
Entity Information [Line Items]
 
 
Document Type
10-Q 
 
Amendment Flag
false 
 
Document Period End Date
Jun. 30, 2016 
 
Document Fiscal Year Focus
2016 
 
Document Fiscal Period Focus
Q2 
 
Entity Registrant Name
AMEREN ILLINOIS CO 
 
Entity Central Index Key
0000018654 
 
Current Fiscal Year End Date
--12-31 
 
Entity Filer Category
Non-accelerated Filer 
 
Entity Common Stock, Shares Outstanding
 
25,452,373 
Consolidated Statement of Income (Loss) (USD $)
In Millions, except Per Share data, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Operating Revenues:
 
 
 
 
Electric
$ 1,274 
$ 1,250 
$ 2,376 
$ 2,393 
Gas
153 
151 
485 
564 
Total operating revenues
1,427 
1,401 
2,861 
2,957 
Operating Expenses:
 
 
 
 
Fuel
166 
205 
369 
411 
Purchased power
135 
101 
273 
240 
Gas purchased for resale
41 
46 
193 
282 
Other operations and maintenance
435 
427 
835 
828 
Provision for Callaway construction and operating license
0 
69 
0 
69 
Depreciation and amortization
210 
200 
417 
393 
Taxes other than income taxes
115 
116 
229 
241 
Total operating expenses
1,102 
1,164 
2,316 
2,464 
Operating Income
325 
237 
545 
493 
Other Income and Expenses:
 
 
 
 
Miscellaneous income
16 1
16 1
36 1
35 1
Miscellaneous expense
6 1
6 1
13 1
17 1
Total other income (expense)
10 
10 
23 
18 
Interest Charges
95 
89 
190 
177 
Income Before Income Taxes
240 
158 
378 
334 
Income Taxes
92 
59 
123 
125 
Income from Continuing Operations
148 
99 
255 
209 
Income from Discontinued Operations, Net of Taxes
0 
52 
0 
52 
Net Income (Loss)
148 
151 
255 
261 
Pension and other postretirement benefit plan activity, net of income taxes (benefit)
4 
4 
2 
4 
Comprehensive Income
151 
154 
254 
262 
Less: Net Income (Loss) Attributable to Noncontrolling Interests:
 
 
 
 
Net Income from Continuing Operations Attributable to Noncontrolling Interests
1 
1 
3 
3 
Net Income (Loss):
 
 
 
 
Continuing Operations
147 
98 
252 
206 
Discontinued Operations
0 
52 
0 
52 
Net Income (Loss)
147 
150 
252 
258 
Earnings Per Share, Basic [Abstract]
 
 
 
 
Continuing Operations
$ 0.61 
$ 0.40 
$ 1.04 
$ 0.85 
Discontinued Operations
$ 0 
$ 0.21 
$ 0 
$ 0.21 
Earnings Per Share, Basic
$ 0.61 
$ 0.61 
$ 1.04 
$ 1.06 
Dividends per Common Share
$ 0.425 
$ 0.41 
$ 0.85 
$ 0.82 
Average Common Shares Outstanding - Basic
242.6 
242.6 
242.6 
242.6 
Union Electric Company
 
 
 
 
Operating Revenues:
 
 
 
 
Electric
844 
859 
1,538 
1,601 
Gas
23 
24 
70 
82 
Other Revenue, Net
0 
1 
0 
1 
Total operating revenues
867 
884 
1,608 
1,684 
Operating Expenses:
 
 
 
 
Fuel
166 
205 
369 
411 
Purchased power
50 
19 
92 
58 
Gas purchased for resale
6 
7 
27 
38 
Other operations and maintenance
238 
229 
450 
440 
Provision for Callaway construction and operating license
0 
69 
0 
69 
Depreciation and amortization
127 
124 
254 
242 
Taxes other than income taxes
83 
85 
156 
165 
Total operating expenses
670 
738 
1,348 
1,423 
Operating Income
197 
146 
260 
261 
Other Income and Expenses:
 
 
 
 
Miscellaneous income
9 
12 
24 
23 
Miscellaneous expense
2 
2 
4 
5 
Total other income (expense)
7 
10 
20 
18 
Interest Charges
53 
55 
105 
110 
Income Before Income Taxes
151 
101 
175 
169 
Income Taxes
58 
39 
67 
65 
Net Income (Loss)
93 
62 
108 
104 
Other Comprehensive Income
0 
0 
0 
0 
Comprehensive Income
93 
62 
108 
104 
Net Income (Loss):
 
 
 
 
Net Income (Loss)
93 
62 
108 
104 
Earnings Per Share, Basic [Abstract]
 
 
 
 
Preferred Stock Dividends
1 
1 
2 
2 
Net Income Available to Common Stockholder
92 
61 
106 
102 
Ameren Illinois Company
 
 
 
 
Operating Revenues:
 
 
 
 
Electric
411 
386 
803 
776 
Gas
131 
127 
416 
482 
Total operating revenues
542 
513 
1,219 
1,258 
Operating Expenses:
 
 
 
 
Purchased power
90 
87 
194 
189 
Gas purchased for resale
35 
39 
166 
244 
Other operations and maintenance
200 
202 
394 
404 
Depreciation and amortization
80 
73 
157 
146 
Taxes other than income taxes
30 
29 
68 
72 
Total operating expenses
435 
430 
979 
1,055 
Operating Income
107 
83 
240 
203 
Other Income and Expenses:
 
 
 
 
Miscellaneous income
6 
4 
11 
11 
Miscellaneous expense
3 
2 
8 
7 
Total other income (expense)
3 
2 
3 
4 
Interest Charges
35 
33 
70 
66 
Income Before Income Taxes
75 
52 
173 
141 
Income Taxes
29 
20 
67 
55 
Net Income (Loss)
46 
32 
106 
86 
Pension and other postretirement benefit plan activity, net of income taxes (benefit)
(1)
(1)
(2)
(2)
Comprehensive Income
45 
31 
104 
84 
Net Income (Loss):
 
 
 
 
Net Income (Loss)
46 
32 
106 
86 
Earnings Per Share, Basic [Abstract]
 
 
 
 
Preferred Stock Dividends
1 
1 
2 
2 
Net Income Available to Common Stockholder
$ 45 
$ 31 
$ 104 
$ 84 
Consolidated Statement of Income (Loss) (Parenthetical) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Pension and other postretirement benefit plan activity, tax expense (benefit)
$ 3 
$ 4 
$ 4 
$ 4 
Ameren Illinois Company
 
 
 
 
Pension and other postretirement benefit plan activity, tax expense (benefit)
$ 0 
$ 0 
$ (1)
$ (1)
Consolidated Statement of Comprehensive Income (Loss) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
 
 
 
 
Income from Continuing Operations
$ 148 
$ 99 
$ 255 
$ 209 
Other Comprehensive Income from Continuing Operations, Net of Taxes
 
 
 
 
Pension and other postretirement benefit plan activity, net of income taxes (benefit)
4 
4 
2 
4 
Comprehensive Income from Continuing Operations
152 
103 
257 
213 
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests
1 
1 
3 
3 
Comprehensive Income from Continuing Operations Attributable to Ameren Common Shareholders
151 
102 
254 
210 
Income from Discontinued Operations, Net of Taxes
0 
52 
0 
52 
Other Comprehensive Income from Discontinued Operations, Net of Tax
0 
0 
0 
0 
Comprehensive Income from Discontinued Operations Attributable to Ameren Common Shareholders
0 
52 
0 
52 
Comprehensive Income Attributable to Ameren Common Shareholders
$ 151 
$ 154 
$ 254 
$ 262 
Consolidated Statement of Comprehensive Income (Loss) Consolidated Statement of Income (Parenthetical) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
 
 
 
 
Pension and other postretirement benefit plan activity, tax expense (benefit)
$ 3 
$ 4 
$ 4 
$ 4 
Consolidated Balance Sheet (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Current Assets:
 
 
Cash and cash equivalents
$ 13 
$ 292 
Accounts receivable - trade (less allowance for doubtful accounts)
445 
388 
Unbilled revenue
328 
239 
Miscellaneous accounts and notes receivable
65 
98 
Materials and supplies
515 
538 
Current regulatory assets
146 
260 
Other current assets
68 
88 
Assets of discontinued operations
14 
14 
Total current assets
1,594 
1,917 
Property and Plant, Net
19,324 
18,799 
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
582 
556 
Goodwill
411 
411 
Regulatory assets
1,330 
1,382 
Other assets
552 
575 
Total investments and other assets
2,875 
2,924 
TOTAL ASSETS
23,793 
23,640 
Current Liabilities:
 
 
Current maturities of long-term debt
431 
395 
Short-term Debt
778 
301 
Accounts and wages payable
499 
777 
Taxes accrued
124 
43 
Interest accrued
102 
89 
Customer deposits
100 
100 
Current regulatory liabilities
99 
80 
Other current liabilities
270 
279 
Liabilities of discontinued operations
27 
29 
Total current liabilities
2,430 
2,093 
Long-term Debt, Net
6,605 
6,880 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
4,028 
3,885 
Accumulated deferred investment tax credits
57 
60 
Regulatory liabilities
1,953 
1,905 
Asset retirement obligations
629 
618 
Pension and other postretirement benefits
537 
580 
Other deferred credits and liabilities
490 
531 
Total deferred credits and other liabilities
7,694 
7,579 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
2 
2 
Other paid-in capital
5,545 
5,616 
Retained earnings
1,376 
1,331 
Accumulated other comprehensive income (loss)
(1)
(3)
Stockholder's equity
6,922 
6,946 
Noncontrolling Interest
142 
142 
Total equity
7,064 
7,088 
TOTAL LIABILITIES AND EQUITY
23,793 
23,640 
Union Electric Company
 
 
Current Assets:
 
 
Cash and cash equivalents
0 
199 
Advances to money pool
0 
36 
Accounts receivable - trade (less allowance for doubtful accounts)
206 
174 
Accounts receivable - affiliates
15 
54 
Unbilled revenue
226 
128 
Miscellaneous accounts and notes receivable
52 
78 
Materials and supplies
396 
387 
Current regulatory assets
46 
89 
Other current assets
33 
41 
Total current assets
974 
1,186 
Property and Plant, Net
11,242 
11,183 
Investments and Other Assets:
 
 
Nuclear decommissioning trust fund
582 
556 
Regulatory assets
536 
605 
Other assets
315 
321 
Total investments and other assets
1,433 
1,482 
TOTAL ASSETS
13,649 
13,851 
Current Liabilities:
 
 
Current maturities of long-term debt
431 
266 
Short-term Debt
77 
0 
Accounts and wages payable
204 
417 
Accounts payable - affiliates
40 
56 
Taxes accrued
113 
31 
Interest accrued
68 
59 
Current regulatory liabilities
21 
28 
Other current liabilities
139 
120 
Total current liabilities
1,093 
977 
Long-term Debt, Net
3,568 
3,844 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
2,915 
2,844 
Accumulated deferred investment tax credits
55 
58 
Regulatory liabilities
1,197 
1,172 
Asset retirement obligations
623 
612 
Pension and other postretirement benefits
195 
234 
Other deferred credits and liabilities
24 
28 
Total deferred credits and other liabilities
5,009 
4,948 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
511 
511 
Other paid-in capital
1,822 
1,822 
Preferred stock
80 
80 
Retained earnings
1,566 
1,669 
Stockholder's equity
3,979 
4,082 
TOTAL LIABILITIES AND EQUITY
13,649 
13,851 
Ameren Illinois Company
 
 
Current Assets:
 
 
Cash and cash equivalents
0 
71 
Accounts receivable - trade (less allowance for doubtful accounts)
225 
204 
Accounts receivable - affiliates
15 
22 
Unbilled revenue
102 
111 
Miscellaneous accounts and notes receivable
12 
19 
Materials and supplies
119 
151 
Current regulatory assets
98 
167 
Other current assets
11 
15 
Total current assets
582 
760 
Property and Plant, Net
7,121 
6,848 
Investments and Other Assets:
 
 
Goodwill
411 
411 
Regulatory assets
786 
771 
Other assets
99 
113 
Total investments and other assets
1,296 
1,295 
TOTAL ASSETS
8,999 
8,903 
Current Liabilities:
 
 
Current maturities of long-term debt
0 
129 
Short-term Debt
177 
0 
Accounts and wages payable
212 
249 
Accounts payable - affiliates
43 
66 
Taxes accrued
9 
13 
Interest accrued
29 
28 
Customer deposits
67 
69 
Mark-to-market derivative liabilities
23 
45 
Current environmental remediation
35 
28 
Current regulatory liabilities
59 
39 
Other current liabilities
88 
86 
Total current liabilities
742 
752 
Long-term Debt, Net
2,343 
2,342 
Deferred Credits and Other Liabilities:
 
 
Accumulated deferred income taxes, net
1,546 
1,480 
Accumulated deferred investment tax credits
2 
2 
Regulatory liabilities
754 
732 
Pension and other postretirement benefits
284 
271 
Environmental remediation
183 
205 
Other deferred credits and liabilities
207 
222 
Total deferred credits and other liabilities
2,976 
2,912 
Commitments and Contingencies
   
   
Stockholders' Equity:
 
 
Common Stock
0 
0 
Other paid-in capital
2,005 
2,005 
Preferred stock
62 
62 
Retained earnings
868 
825 
Accumulated other comprehensive income (loss)
3 
5 
Stockholder's equity
2,938 
2,897 
TOTAL LIABILITIES AND EQUITY
$ 8,999 
$ 8,903 
Consolidated Balance Sheet (Parenthetical) (USD $)
In Millions, except Per Share data, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Accounts receivable - trade allowance for doubtful accounts
$ 21 
$ 19 
Common stock, par value
$ 0.01 
$ 0.01 
Common stock, shares authorized
400.0 
400.0 
Common stock, shares outstanding
242.6 
242.6 
Union Electric Company
 
 
Accounts receivable - trade allowance for doubtful accounts
7 
7 
Common stock, par value
$ 5 
$ 5 
Common stock, shares authorized
150.0 
150.0 
Common stock, shares outstanding
102.1 
102.1 
Ameren Illinois Company
 
 
Accounts receivable - trade allowance for doubtful accounts
$ 14 
$ 12 
Common stock, no par value
$ 0 
$ 0 
Common stock, shares authorized
45.0 
45.0 
Common stock, shares outstanding
25.5 
25.5 
Consolidated Statement of Cash Flows (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Cash Flows From Operating Activities:
 
 
Net income
$ 255 
$ 261 
(Income) from discontinued operations, net of taxes
0 
(52)
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
Provision for Callaway construction and operating license
0 
69 
Depreciation and amortization
419 
387 
Amortization of nuclear fuel
38 
47 
Amortization of debt issuance costs and premium/discounts
11 
11 
Deferred income taxes and investment tax credits, net
134 
116 
Allowance for equity funds used during construction
(13)1
(11)1
Share-based compensation costs
12 
14 
Other
(7)
(13)
Changes in assets and liabilities:
 
 
Receivables
(111)
(80)
Materials and supplies
23 
25 
Accounts and wages payable
(200)
(180)
Taxes accrued
80 
83 
Regulatory assets and liabilities
108 
65 
Assets, other
24 
27 
Liabilities, other
(12)
(15)
Pension and other postretirement benefits
4 
28 
Net cash provided by operating activities – continuing operations
765 
782 
Net cash used in operating activities – discontinued operations
(2)
(1)
Net cash provided by operating activities
763 
781 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(1,000)
(846)
Nuclear fuel expenditures
(24)
(28)
Purchases of securities - nuclear decommissioning trust fund
(201)
(117)
Sales and maturities of securities - nuclear decommissioning trust fund
192 
110 
Proceeds from Notes Receivable
0 
10 
Contributions to Note Receivable
0 
(7)
Other
(2)
3 
Net cash used in investing activities – continuing operations
(1,035)
(875)
Net cash used in investing activities – discontinued operations
0 
0 
Net cash used in investing activities
(1,035)
(875)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
(206)
(199)
Dividends paid to noncontrolling interest holders
(3)
(3)
Short-term debt, net
477 
172 
Maturities of Long-term Debt
(389)
(114)
Issuances of Long-term Debt
149 
249 
Employee payroll taxes related to share-based payments
(32)
(12)
Capital Issuance Costs
(1)
(2)
Other
(2)
0 
Net cash provided by (used in) financing activities – continuing operations
(7)
91 
Net change in cash and cash equivalents
(279)
(3)
Cash and cash equivalents at beginning of period
292 
5 
Cash and cash equivalents at end of period
13 
2 
Union Electric Company
 
 
Cash Flows From Operating Activities:
 
 
Net income
108 
104 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
Provision for Callaway construction and operating license
0 
69 
Depreciation and amortization
257 
238 
Amortization of nuclear fuel
38 
47 
Amortization of debt issuance costs and premium/discounts
3 
3 
Deferred income taxes and investment tax credits, net
66 
27 
Allowance for equity funds used during construction
(10)
(9)
Changes in assets and liabilities:
 
 
Receivables
(103)
(80)
Materials and supplies
(9)
(24)
Accounts and wages payable
(174)
(180)
Taxes accrued
80 
123 
Regulatory assets and liabilities
55 
63 
Assets, other
14 
16 
Liabilities, other
37 
35 
Pension and other postretirement benefits
2 
14 
Net cash provided by operating activities
364 
446 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(353)
(289)
Nuclear fuel expenditures
(24)
(28)
Purchases of securities - nuclear decommissioning trust fund
(201)
(117)
Sales and maturities of securities - nuclear decommissioning trust fund
192 
110 
Money pool advances, net
36 
0 
Other
(4)
(4)
Net cash used in investing activities
(354)
(328)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
(210)
(415)
Dividends on preferred stock
(2)
(2)
Short-term debt, net
77 
(59)
Maturities of Long-term Debt
(260)
(114)
Issuances of Long-term Debt
149 
249 
Capital contribution from parent
38 
224 
Capital Issuance Costs
(1)
(2)
Net cash provided by (used in) financing activities
(209)
(119)
Net change in cash and cash equivalents
(199)
(1)
Cash and cash equivalents at beginning of period
199 
1 
Cash and cash equivalents at end of period
0 
0 
Ameren Illinois Company
 
 
Cash Flows From Operating Activities:
 
 
Net income
106 
86 
Adjustments to reconcile net income to net cash provided by operating activities:
 
 
Depreciation and amortization
156 
144 
Amortization of debt issuance costs and premium/discounts
7 
7 
Deferred income taxes and investment tax credits, net
65 
45 
Allowance for equity funds used during construction
(3)
(2)
Other
(6)
(5)
Changes in assets and liabilities:
 
 
Receivables
(5)
57 
Materials and supplies
32 
48 
Accounts and wages payable
(20)
20 
Taxes accrued
(14)
(6)
Regulatory assets and liabilities
48 
(1)
Assets, other
11 
8 
Liabilities, other
(1)
(29)
Pension and other postretirement benefits
3 
12 
Net cash provided by operating activities
382 
386 
Cash Flows From Investing Activities:
 
 
Capital expenditures
(442)
(379)
Other
4 
4 
Net cash used in investing activities
(438)
(375)
Cash Flows From Financing Activities:
 
 
Dividends on common stock
(60)
0 
Dividends on preferred stock
(2)
(2)
Short-term debt, net
177 
(20)
Money pool borrowings, net
0 
10 
Maturities of Long-term Debt
(129)
0 
Other
(1)
0 
Net cash provided by (used in) financing activities
(15)
(12)
Net change in cash and cash equivalents
(71)
(1)
Cash and cash equivalents at beginning of period
71 
1 
Cash and cash equivalents at end of period
$ 0 
$ 0 
Summary Of Significant Accounting Policies
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
General
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005. Ameren’s primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below. Also see the Glossary of Terms and Abbreviations at the front of this report and in the Form 10-K.
•
Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas transmission and distribution business in Missouri.
•
Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric and natural gas transmission and distribution businesses in Illinois.
Additionally, Ameren has a subsidiary, ATXI, that operates a FERC rate-regulated electric transmission business. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers, Spoon River, and Mark Twain projects. Ameren is also pursuing projects to improve electric transmission system reliability within Ameren Missouri's and Ameren Illinois' service territories as well as competitive electric transmission investment opportunities outside of these territories, including investments outside of MISO. Ameren also has various other subsidiaries that conduct activities such as the provision of shared services.
Unless otherwise stated, these notes to Ameren’s financial statements exclude discontinued operations for all periods presented. See Note 12 – Discontinued Operations in this report and Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K for additional information.
Ameren’s financial statements are prepared on a consolidated basis and therefore include the accounts of its majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Missouri and Ameren Illinois have no subsidiaries, and therefore their financial statements are not prepared on a consolidated basis. All tabular dollar amounts are in millions, unless otherwise indicated.
Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair statement of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates. The results of operations of an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K.
Asset Retirement Obligations
AROs at Ameren, Ameren Missouri, and Ameren Illinois increased during the six months ended June 30, 2016 to reflect the accretion of obligations to their fair value, partially offset by immaterial settlements.
Share-based Compensation
A summary of nonvested performance share units at June 30, 2016, and changes during the six months ended June 30, 2016, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below:
 
Performance Share Units
 
Share Units
 
Weighted-average Fair Value per Share Unit
Nonvested at January 1, 2016
1,024,870

 
$
46.08

Granted(a)
584,312

 
44.13

Forfeitures
(15,949
)
 
45.07

Vested(b)
(10,754
)
 
43.44

Nonvested at June 30, 2016
1,582,479

 
$
45.39

(a)
Performance share units granted to certain executive and nonexecutive officers and other eligible employees under the 2014 Incentive Plan.
(b)
Performance share units vested due to the attainment of retirement eligibility by certain employees. Actual shares issued for retirement-eligible employees will vary depending on actual performance over the three-year measurement period.
The fair value of each performance share unit awarded in 2016 under the 2014 Incentive Plan was determined to be $44.13, which was based on Ameren’s closing common share price of $43.23 at December 31, 2015, and lattice simulations. Lattice simulations are used to estimate expected share payout based on Ameren’s total shareholder return for a three-year performance period relative to the designated peer group beginning January 1, 2016. The simulations can produce a greater fair value for the performance share unit than the December 31 applicable closing common share price because they include the weighted payout scenarios in which an increase in the share price has occurred. The significant assumptions used to calculate fair value also included a three-year risk-free rate of 1.31%, volatility of 15% to 20% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period.
Excise Taxes
Ameren Missouri and Ameren Illinois collect certain excise taxes from customers that are levied on the sale or distribution of natural gas and electricity. Excise taxes are levied on Ameren Missouri’s electric and natural gas businesses and on Ameren Illinois’ natural gas business and are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes for electric service in Illinois are levied on the customer and are therefore not included in Ameren Illinois’ revenues and expenses. The following table presents excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” for the three and six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
2016
 
2015
 
2016
 
2015
Ameren Missouri
$
40

 
$
41

 
$
70

 
$
75

Ameren Illinois
11

 
10

 
31

 
33

Ameren
$
51

 
$
51

 
$
101

 
$
108


Earnings Per Share
There were no material differences between Ameren’s basic and diluted earnings per share amounts for the six months ended June 30, 2016 and 2015. The assumed settlement of dilutive performance share units had an immaterial impact on earnings per share. The calculation of diluted earnings per share reflected the adoption of FASB guidance related to employee share-based payment accounting discussed below.
Accounting and Reporting Developments
Below is a summary of recently issued authoritative accounting standards relevant to the Ameren Companies.
Revenue from Contracts with Customers
In May 2014, the FASB issued authoritative accounting guidance that changes the criteria for recognizing revenue from a contract with a customer. The underlying principle of the guidance is that an entity will recognize revenue for the transfer of promised goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires additional disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Entities can apply the guidance retrospectively to each reporting period presented or retrospectively by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impact of this guidance on their results of operations, financial position, and disclosures, including their accounting for contributions in aid of construction and similar arrangements, as well as the transition method that they will use to adopt the guidance. The guidance will be effective for the Ameren Companies in the first quarter of 2018.
Amendments to the Consolidation Analysis
In February 2015, the FASB issued authoritative accounting guidance that amends the consolidation analysis for variable interest entities and voting interest entities. The new guidance affects (1) limited partnerships, similar legal entities, and certain investment funds, (2) the evaluation of fees paid to a decision maker or service provider as a variable interest, (3) how fee arrangements impact the primary beneficiary determination, and (4) the evaluation of related party relationships on the primary beneficiary determination. The adoption of this guidance in the first quarter of 2016 did not impact the Ameren Companies’ results of operations, financial position, liquidity, or disclosures.
Leases
In February 2016, the FASB issued authoritative accounting guidance that will require an entity to recognize assets and liabilities arising from a lease. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease will depend primarily on its classification as a finance or operating lease. The guidance also requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. The guidance will be effective for the Ameren Companies in the first quarter of 2019 with an option for entities to adopt early. Upon adoption, the Ameren Companies will recognize and measure operating leases on their respective balance sheets at the beginning of the earliest period presented. The Ameren Companies are currently assessing the impact of this guidance on their results of operations, financial position, statement of cash flows, and disclosures.
Improvements to Employee Share-Based Payment Accounting
In March 2016, the FASB issued authoritative accounting guidance that simplifies the accounting for share-based payment transactions, including the income tax consequences, the calculation of diluted earnings per share, the treatment of forfeitures, the classification of awards as either equity or liabilities, and the classification on the statement of cash flows. Ameren determines for each performance share unit award whether the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes results in either an excess tax benefit or an excess tax deficit. Previously, excess tax benefits were recognized in "Other paid-in capital" on Ameren’s consolidated balance sheet, and in certain cases, excess tax deficits were recognized in “Income taxes” on Ameren’s consolidated income statement. The new guidance increases income statement volatility by requiring all excess tax benefits and deficits to be recognized in “Income taxes,” and treated as discrete items in the period in which they occur. Ameren adopted this guidance in the first quarter of 2016 and prospectively applied the amendment in this guidance requiring recognition of excess tax benefits and deficits in the income statement, which resulted in recognition of a $21 million income tax benefit and a corresponding $21 million increase in income from continuing operations and net income (9 cents per diluted share) during the period. Also as a result of the adoption of this guidance, Ameren made an accounting policy election to continue to estimate the number of forfeitures expected to occur. The amendments in the guidance that require application using a modified retrospective transition method did not impact Ameren. Therefore, there was no cumulative-effect adjustment to retained earnings recognized as of January 1, 2016. Ameren applied the amendments in this guidance relating to classification on the statement of cash flows retrospectively. As a result, for the six months ended June 30, 2015, Ameren reclassified, for comparison purposes, $2 million of excess tax benefits on the statement of cash flows from financing to operating activity, and $12 million of employee payroll taxes related to share-based payments from operating to financing activity.
Rate And Regulatory Matters
RATE AND REGULATORY MATTERS
RATE AND REGULATORY MATTERS
Below is a summary of updates to significant regulatory proceedings and related lawsuits. See also Note 2 – Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.
Missouri
2016 Electric Rate Case
On July 1, 2016, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service by $206 million. The electric rate increase request is based on a 9.9% return on equity, a capital structure composed of 51.8% equity, a rate base of $7.2 billion, and a test year ended March 31, 2016, with certain pro-forma adjustments expected through the anticipated true-up date of December 31, 2016. The rate request includes $74 million that is primarily related to nearly $1.4 billion of gross electric infrastructure investments that have been placed into service since the true-up date in Ameren Missouri’s last electric rate case. This $74 million includes depreciation expenses of $39 million, return on rate base of $25 million, and increased property taxes of $10 million. The rate request also includes $51 million related to reduced customer sales volumes, including reductions from the idling of operations at Noranda’s aluminum smelter, and $34 million related to increases in transmission charges. Other changes in expenses reflected in the rate request include decreases in pension and other post-employment benefit plan expenses of $24 million and solar rebate expenses of $15 million, both of which are subject to regulatory tracking mechanisms; increased net energy costs, excluding the impact of reduced Noranda and other customer sales volumes, of $23 million; and increased income taxes of $15 million.
As a part of its filing, Ameren Missouri requested the amortization over ten years of an estimated $81 million of lost fixed cost recovery due to lower sales volumes, as discussed below, from Noranda during the period April 2015 through May 2017.
Ameren Missouri also requested continued use of its FAC and the regulatory tracking mechanisms for pension and postretirement benefits and uncertain income tax positions that the MoPSC previously authorized in earlier electric rate orders. Additionally, Ameren Missouri requested the implementation of a new regulatory tracking mechanism for transmission charges and revenues.
The MoPSC proceeding relating to the proposed electric service rate changes will take place over a period of up to 11 months, with a decision by the MoPSC expected by late April 2017 and new rates effective in late May 2017. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, when any rate change may go into effect, whether the requested regulatory tracking mechanisms will be approved, or whether any rate increase that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the increase goes into effect.
Noranda
In the first quarter of 2016, Noranda idled production at its aluminum smelter and filed voluntary petitions for a court-supervised restructuring process under Chapter 11 of the United States Bankruptcy Code. As of June 30, 2016, Ameren Missouri has been, and expects to continue to be, paid in full for its electric service provided to Noranda.
In its April 2015 electric rate order, the MoPSC approved a rate design that established $78 million in annual revenues, net of fuel and purchased power costs, as Noranda’s portion of Ameren Missouri’s revenue requirement. The portion of Ameren Missouri’s annual revenue requirement reflected in Noranda’s electric rate is based on the smelter using approximately 4.2 million megawatthours annually, which is almost 100% of its operating capacity. Ameren Missouri’s rates, including those for Noranda, are seasonal. Noranda’s summer base rate (June through September) is $45.78 per megawatthour, and its winter base rate (October through May) is $31.11 per megawatthour.
In 2016, actual sales volumes to Noranda will be significantly below the sales volumes reflected in rates. As a result, full recovery by Ameren Missouri of its revenue requirement has not occurred and will not occur until rates are adjusted prospectively by the MoPSC in the July 2016 electric rate case to accurately reflect Noranda’s actual sales volumes. Ameren Missouri is seeking to recover the April 2015 through May 2017 lost fixed costs caused by the lower Noranda sales volumes in its July 2016 electric rate case. Also as a result of Noranda’s idled production described above, Ameren Missouri is applying a provision in its FAC tariff that, under certain circumstances, allows Ameren Missouri to retain a portion of the revenues from any off-system sales it makes as a result of reduced tariff sales to Noranda. The current market price of electricity is less than Noranda’s electric rate, and Ameren Missouri expects market prices to remain below Noranda’s electric rate during 2016. Accordingly, this FAC-tariff provision will not enable Ameren Missouri to fully recover its revenue requirement under current market conditions.
MEEIA 2013
The MEEIA 2013 performance incentive allowed Ameren Missouri an opportunity to earn additional revenues by achieving certain customer energy efficiency goals, including $19 million if 100% of the goals were achieved during the three-year period, with the potential to earn a larger performance incentive if Ameren Missouri’s energy savings exceeded those goals. Ameren Missouri has not recorded any revenues associated with the MEEIA 2013 performance incentive. Ameren Missouri believes it will ultimately be found to have exceeded 100% of the customer energy efficiency goals. Therefore, regardless of the outcome of the appeal discussed below, Ameren Missouri expects to recognize revenues relating to the MEEIA 2013 performance incentive of at least $19 million in 2016.
In November 2015, the MoPSC issued an order that clarified the method applied to determine an input used to calculate the performance incentive. Ameren Missouri filed an appeal of the order with the Missouri Court of Appeals, Western District, which is expected to issue a decision in 2016. If the Missouri Court of Appeals overturns the MoPSC’s November 2015 order, the MEEIA 2013 performance incentive will be more than the performance incentive calculated using the MoPSC’s November 2015 order.
ATXI Transmission Projects
The Mark Twain project is a MISO-approved 95-mile transmission line located in northeast Missouri. In April 2016, the MoPSC granted ATXI a certificate of convenience and necessity for the Mark Twain project. Starting construction under the certificate is subject to ATXI obtaining assents from the five counties where the line will be constructed. The Mark Twain project is expected to be completed in 2018. Extended difficulties in obtaining the assents could delay the completion date. ATXI is in the process of obtaining the assents.
Illinois
IEIMA
Under the provisions of the IEIMA's performance-based formula rate-making framework, which currently extends through 2019, Ameren Illinois’ electric distribution service rates are subject to an annual revenue requirement reconciliation to its actual recoverable costs. Throughout each year, Ameren Illinois records a regulatory asset or a regulatory liability and a corresponding increase or decrease to operating revenues for any differences between the revenue requirement reflected in customer rates for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual recoverable costs incurred. As of June 30, 2016, Ameren Illinois had recorded regulatory assets of $12 million, $66 million, and $58 million to reflect its expected 2016 and 2015 revenue requirement reconciliation adjustments and the approved 2014 revenue requirement reconciliation adjustment, with interest, respectively.
In April 2016, Ameren Illinois filed with the ICC its annual electric distribution service formula rate update to establish the revenue requirement used for 2017 rates. Pending ICC approval, and if approved as filed, Ameren Illinois’ update filing would result in a $14 million decrease in Ameren Illinois’ electric distribution service revenue requirement, beginning in January 2017. This update reflects an increase to the annual formula rate based on 2015 actual costs and expected net plant additions for 2016, an increase to include the 2015 revenue requirement reconciliation adjustment, and a decrease for the conclusion of the 2014 revenue requirement reconciliation adjustment, which will be fully collected from customers in 2016, consistent with the ICC’s December 2015 annual update filing order. As of December 31, 2015, Ameren Illinois had recorded a regulatory asset of $103 million related to the approved 2014 revenue requirement reconciliation adjustment. In July 2016, the ICC staff submitted its calculation of the revenue requirement included in Ameren Illinois’ update filing. The ICC staff recommended a decrease in the electric distribution service revenue requirement in an amount consistent with Ameren Illinois’ filing. Other intervenors to this rate proceeding have recommended additional decreases to Ameren Illinois’ electric distribution service revenue requirement. An ICC decision on the revenue requirement used for 2017 rates is expected by December 2016.
Federal
FERC Complaint Cases
In November 2013, a customer group filed a complaint case with the FERC seeking a reduction in the allowed base return on common equity for the FERC-regulated transmission rate base under the MISO tariff from 12.38% to 9.15%. In December 2015, an administrative law judge issued an initial decision in the November 2013 complaint case that would lower the allowed base return on common equity to 10.32% and would require customer refunds to be issued for the 15-month period ending February 2015. The FERC is expected to issue a final order in the November 2013 complaint case in the fourth quarter of 2016, which will determine the allowed base return on common equity for the 15-month period ending February 2015. The final order in the November 2013 complaint case will also establish a new allowed base return on equity that will replace the current allowed base return on common equity of 12.38% for the period between the effective date of the November 2013 complaint case order and the effective date of the allowed base return on common equity established by the February 2015 complaint case, as discussed below.
After the maximum FERC-allowed refund period for the November 2013 complaint case ended in February 2015, another customer complaint case was filed in February 2015. The February 2015 complaint case seeks a reduction in the allowed base return on common equity for the FERC-regulated transmission rate base under the MISO tariff to 8.67%. In June 2016, an administrative law judge issued an initial decision in the February 2015 complaint case that would lower the allowed base return on common equity to 9.70% and would require customer refunds to be issued for the 15-month period ending May 2016. The FERC is expected to issue a final order in the February 2015 complaint case in the second quarter of 2017, which will determine the allowed base return on common equity for the 15-month period ending May 2016. The final order in the February 2015 complaint case will also establish the allowed base return on common equity that will apply prospectively from the effective date of the February 2015 complaint case order, replacing the allowed base return on equity established by the November 2013 complaint case.
On January 6, 2015, a FERC-approved incentive adder of up to 50 basis points on the allowed base return on common equity for our participation in an RTO became effective. Beginning with its January 6, 2015 effective date, the incentive adder will reduce any refund to customers relating to a reduction of the allowed base return on common equity from the complaint cases discussed above.
As of June 30, 2016, Ameren and Ameren Illinois recorded current regulatory liabilities of $58 million and $39 million, respectively, to reflect the potential refunds associated with the reduced allowed base returns on common equity in the initial decisions for the November 2013 and February 2015 complaint cases. Ameren’s and Ameren Illinois’ liabilities also reflect the January 6, 2015 incentive adder discussed above. Ameren Missouri did not record a liability as of June 30, 2016, and it does not expect that a reduction in the FERC-allowed base return on common equity for MISO transmission owners would be material to its results of operations, financial position, or liquidity.
Combined Construction and Operating License
In 2008, Ameren Missouri filed an application with the NRC for a COL for a second nuclear unit at Ameren Missouri's existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a second nuclear unit at its existing Callaway site, and the NRC suspended review of the COL application. Prior to suspending its efforts, Ameren Missouri had capitalized $69 million related to the project. Primarily because of changes in vendor support for licensing efforts at the NRC, Ameren Missouri’s assessment of long-term capacity needs, declining costs of alternative generation technologies, and the regulatory framework in Missouri, Ameren Missouri discontinued its efforts to license and build a second nuclear unit at its existing Callaway site. As a result of this decision, in the second quarter of 2015, Ameren and Ameren Missouri recognized a $69 million noncash pretax provision for all of the previously capitalized COL costs. Ameren Missouri has withdrawn its COL application with the NRC.
Short-Term Debt And Liquidity
SHORT-TERM DEBT AND LIQUIDITY
SHORT-TERM DEBT AND LIQUIDITY
The liquidity needs of the Ameren Companies are typically supported through the use of available cash, drawings under committed credit agreements, commercial paper issuances, or, in the case of Ameren Missouri and Ameren Illinois, short-term intercompany borrowings.
The Missouri Credit Agreement and the Illinois Credit Agreement, both of which expire on December 11, 2019, were not utilized for direct borrowings during the six months ended June 30, 2016, but were used to support commercial paper issuances and to issue letters of credit. Based on letters of credit issued under the Credit Agreements, as well as commercial paper outstanding, the aggregate amount of credit capacity available under the Credit Agreements to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, at June 30, 2016, was $1.3 billion.
Commercial Paper
The following table presents commercial paper outstanding as of June 30, 2016, and December 31, 2015:
  
June 30, 2016
 
December 31, 2015
Ameren (parent)
$
524

 
$
301

Ameren Missouri
77

 
—

Ameren Illinois
177

 
—

Ameren Consolidated
$
778

 
$
301

The following table summarizes the borrowing activity and relevant interest rates under Ameren’s (parent), Ameren Missouri’s, and Ameren Illinois’ commercial paper programs for the six months ended June 30, 2016 and 2015:
 
 
Ameren
(parent)
Ameren
Missouri
Ameren
Illinois
Ameren Consolidated
2016
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
402

 
$
117

$
12

$
531

Weighted-average interest rate
 
0.82
%
 
0.74
%
0.79
%
0.80
%
Peak commercial paper during period(a)
 
$
549

 
$
208

$
177

$
839

Peak interest rate
 
0.95
%
 
0.85
%
0.85
%
0.95
%
2015
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
754

 
$
84

$
5

$
843

Weighted-average interest rate
 
0.57
%
 
0.50
%
0.44
%
0.56
%
Peak commercial paper during period(a)
 
$
849

 
$
294

$
39

$
1,108

Peak interest rate
 
0.70
%
 
0.60
%
0.60
%
0.70
%

(a)
The timing of peak commercial paper issuances varies by company; therefore, the peak amounts presented by company might not equal the Ameren Consolidated peak commercial paper issuances for the period.
Indebtedness Provisions and Other Covenants
The information below is a summary of the Ameren Companies’ compliance with financial covenants in the Credit Agreements. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, in the Form 10-K for a detailed description of these provisions. The Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities.
The Credit Agreements require Ameren, Ameren Missouri, and Ameren Illinois to each maintain consolidated indebtedness of not more than 65% of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements. As of June 30, 2016, the ratios of consolidated indebtedness to consolidated total capitalization, calculated in accordance with the provisions of the Credit Agreements, were 52%, 49%, and 47% for Ameren, Ameren Missouri, and Ameren Illinois, respectively. In addition, under the Credit Agreements, if Ameren does not have a senior long-term unsecured credit rating of at least Baa3 from Moody’s or BBB- from S&P, Ameren is required to maintain a ratio of consolidated funds from operations plus interest expense to consolidated interest expense of at least 2.0 to 1.0. As of June 30, 2016, Ameren’s senior long-term unsecured credit rating exceeded the minimum rating requirements; therefore, the interest coverage requirement was not applicable. Failure of a borrower to satisfy a financial covenant constitutes an immediate default under the applicable Credit Agreement.
The Credit Agreements contain default provisions that apply separately to each borrower; provided, however, that a default of Ameren Missouri or Ameren Illinois under the applicable Credit Agreement will also be deemed to constitute a default of Ameren under such agreement. Defaults include a cross-default resulting from a default of such borrower under any other agreement covering outstanding indebtedness of such borrower and certain subsidiaries (other than project finance subsidiaries and nonmaterial subsidiaries) in excess of $75 million in the aggregate (including under the other Credit Agreement). However, under the default provisions of the Credit Agreements, any default of Ameren under any Credit Agreement that results solely from a default of Ameren Missouri or Ameren Illinois thereunder does not result in a cross-default of Ameren under the other Credit Agreement. Further, the Credit Agreement default provisions provide that an Ameren default under any of the Credit Agreements does not constitute a default by Ameren Missouri or Ameren Illinois.
None of the Ameren Companies' credit agreements or financing arrangements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. The Ameren Companies were in compliance with the covenants in their credit agreements at June 30, 2016.
Money Pools
Ameren has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements.
Ameren Missouri, Ameren Illinois, and ATXI may participate in the utility money pool as both lenders and borrowers. Ameren (parent) and Ameren Services may participate in the utility money pool only as lenders. Surplus internal funds are contributed to the utility money pool from participants. The primary sources of external funds for the utility money pool are the Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the utility money pool at any given time is reduced by the amount of borrowings made by participants, but is increased to the extent that the pool participants advance surplus funds to the utility money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. Participants receiving a loan under the utility money pool must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the utility money pool. The average interest rate for borrowing under the utility money pool for the three and six months ended June 30, 2016, was 0.60% and 0.54%, respectively (2015 - 0.08% for both periods).
See Note 8 – Related Party Transactions for the amount of interest income and expense from the money pool arrangements recorded by the Ameren Companies for the six months ended June 30, 2016 and 2015.
Long-Term Debt And Equity Financings
LONG-TERM DEBT AND EQUITY FINANCINGS
LONG-TERM DEBT AND EQUITY FINANCINGS
Ameren Missouri
In February 2016, Ameren Missouri's $260 million 5.40% senior secured notes matured and were repaid with cash on hand and commercial paper borrowings.
In June 2016, Ameren Missouri issued $150 million of 3.65% senior secured notes due April 15, 2045, with interest payable semiannually on April 15 and October 15 of each year, beginning October 15, 2016. Ameren Missouri received proceeds of $148 million, which were used to repay short-term debt.
Ameren Illinois
In June 2016, Ameren Illinois’ $54 million 6.20% senior secured notes and $75 million 6.25% senior secured notes matured and were repaid with commercial paper borrowings.
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures, credit facilities, and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions, but would restrict the companies’ ability to issue first mortgage bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and first mortgage bonds and preferred stock issuable as of June 30, 2016, at an assumed annual interest rate of 5% and dividend rate of 6%.
 
 
Required Interest
Coverage Ratio(a)
 
Actual Interest
Coverage Ratio
 
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
 
Actual Dividend
Coverage Ratio
 
Preferred Stock
Issuable
 
Ameren Missouri
 
≥2.0
 
4.7
$
3,793
 
≥2.5
 
105.4
$
2,346
 
Ameren Illinois
 
≥2.0
 
6.9
 
3,827
(d) 
≥1.5
 
2.8
 
203
(e) 
(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of first mortgage bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include first mortgage bonds issuable based on retired bond capacity of $1,206 million and $279 million at Ameren Missouri and Ameren Illinois, respectively.
(c)
Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.
(d)
Amount of first mortgage bonds issuable by Ameren Illinois based on unfunded property additions and retired bonds solely under the former IP mortgage indenture. The amount of first mortgage bonds issuable by Ameren Illinois is also subject to the lien restrictions contained in the Illinois Credit Agreement.
(e)
Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.
Ameren's indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million, or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including borrowings under the Credit Agreements or the Ameren commercial paper program, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period.

Ameren Missouri and Ameren Illinois and certain other Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” The FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from retained earnings. In addition, under Illinois law, Ameren Illinois may not pay any dividend on its stock, unless, among other things, its earnings and earned surplus are sufficient to declare and pay a dividend after provision is made for reasonable and proper reserves, or unless Ameren Illinois has specific authorization from the ICC.

Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois committed to the FERC to maintain a minimum of 30% equity in its capital structure. As of June 30, 2016, Ameren Illinois had 51% equity in its capital structure.
In order for the Ameren Companies to issue securities in the future, we have to comply with all applicable requirements in effect at the time of any such issuances.
Off-Balance-Sheet Arrangements
At June 30, 2016, none of the Ameren Companies had off-balance-sheet financing arrangements, other than operating leases entered into in the ordinary course of business, letters of credit, and Ameren parent guarantee arrangements on behalf of its subsidiaries. None of the Ameren Companies expect to engage in any significant off-balance-sheet financing arrangements in the near future.
Other Income and Expenses
OTHER INCOME AND EXPENSES
OTHER INCOME AND EXPENSES
The following table presents the components of “Other Income and Expenses” in the Ameren Companies’ statements of income for the six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Ameren:(a)
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
5

 
$
6

 
$
13

 
$
11

 
Interest income on industrial development revenue bonds
6

 
6

 
13

 
13

 
Interest income
4

 
4

 
8

 
8

 
Other
1

 
—

 
2

 
3

 
Total miscellaneous income
$
16

 
$
16

 
$
36

 
$
35

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
2

 
$
2

 
$
7

 
$
10

 
Other
4

 
4

 
6

 
7

 
Total miscellaneous expense
$
6

 
$
6

 
$
13

 
$
17

 
Ameren Missouri:
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
3

 
$
5

 
$
10

 
$
9

 
Interest income on industrial development revenue bonds
6

 
6

 
13

 
13

 
Interest income
—

 
1

 
—

 
1

 
Other
—

 
—

 
1

  
—

 
Total miscellaneous income
$
9

 
$
12

 
$
24

 
$
23

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
1

 
$
1

 
$
2

 
$
3

 
Other
1

 
1

 
2

 
2

 
Total miscellaneous expense
$
2

 
$
2

 
$
4

 
$
5

 
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Ameren Illinois:
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
2

 
$
1

 
$
3

 
$
2

 
Interest income
3

 
3

 
7

 
7

 
Other
1

 
—

 
1

 
2

 
Total miscellaneous income
$
6

 
$
4

 
$
11

 
$
11

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
1

 
$
1

 
$
5

 
$
4

 
Other
2

 
1

 
3

 
3

 
Total miscellaneous expense
$
3

 
$
2

 
$
8

 
$
7

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Derivative Financial Instruments
DERIVATIVE FINANCIAL INSTRUMENTS
NOTE 6 – DERIVATIVE FINANCIAL INSTRUMENTS
We use derivatives to manage the risk of changes in market prices for natural gas, power, and uranium, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following:
•
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
•
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
•
actual cash outlays for the purchase of these commodities that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.
The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of June 30, 2016, and December 31, 2015. As of June 30, 2016, these contracts extended through October 2018, March 2021, May 2032, and January 2019 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2016
2015
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
24

(b)

24

35

(b)

35

Natural gas (in mmbtu)
30

131

161

30

151

181

Power (in megawatthours)
1

10

11

1

10

11

Uranium (pounds in thousands)
395

(b)

395

494

(b)

494

(a)
Consists of ultra-low-sulfur diesel products.
(b)
Not applicable.
Authoritative accounting guidance regarding derivative instruments requires that all contracts considered to be derivative instruments be recorded on the balance sheet at their fair values, unless the NPNS exception applies. See Note 7 – Fair Value Measurements for a discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery.
If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine whether the resulting gains or losses qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or liabilities in the period in which the change occurs. We believe derivative losses and gains deferred as regulatory assets and liabilities are probable of recovery or refund through future rates charged to customers. Regulatory assets and liabilities are amortized to operating income as related losses and gains are reflected in rates charged to customers. Therefore, gains and losses on these derivatives have no effect on operating income. As of June 30, 2016, and December 31, 2015, all contracts received regulatory deferral.
Authoritative accounting guidance permits companies to offset fair value amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a liability) against fair value amounts recognized for derivative instruments that are executed with the same counterparty under a master netting arrangement or similar agreement. The Ameren Companies did not elect to adopt this guidance for any eligible derivative instruments.
The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of June 30, 2016, and December 31, 2015:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2016
 
 
 
 
 
 
Natural gas
Other current assets
 
$
—

 
$
2

 
$
2

 
Other assets
 
1

 
3

 
4

Power
Other current assets
 
15

 
—

 
15

 
Total assets (a)
 
$
16

 
$
5

 
$
21

Fuel oils
Other current liabilities
 
$
12

 
$
—

 
$
12

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
MTM derivative liabilities
 
(b)

 
11

 
(b)

 
Other current liabilities
 
3

 
—

 
14

 
Other deferred credits and liabilities
 
6

 
6

 
12

Power
MTM derivative liabilities
 
(b)

 
12

 
(b)

 
Other current liabilities
 
1

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
157

 
157

Uranium
Other current liabilities
 
1

 
—

 
1

 
Other deferred credits and liabilities
 
3

 
—

 
3

 
Total liabilities (c)
 
$
28

 
$
186

 
$
214

2015
 
 
 
 
 
 
Natural gas
Other current assets
 
$
—

 
$
1

 
$
1

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
16

 
—

 
16

 
Total assets (a)
 
$
17

 
$
1

 
$
18

Fuel oils
Other current liabilities
 
$
22

 
$
—

 
$
22

 
Other deferred credits and liabilities
 
7

 
—

 
7

Natural gas
MTM derivative liabilities
 
(b)

 
32

 
(b)

 
Other current liabilities
 
6

 
—

 
38

 
Other deferred credits and liabilities
 
8

 
18

 
26

Power
MTM derivative liabilities
 
(b)

 
13

 
(b)

 
Other current liabilities
 
—

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
157

 
157

Uranium
Other current liabilities
 
1

 
—

 
1

 
Total liabilities (c)
 
$
44

 
$
220

 
$
264


(a)
Because all contracts qualifying for hedge accounting receive regulatory deferral, the cumulative amount of pretax net gains on all derivative instruments is deferred as a regulatory liability.
(b)
Balance sheet line item not applicable to registrant.
(c)
Because all contracts qualifying for hedge accounting receive regulatory deferral, the cumulative amount of pretax net losses on all derivative instruments is deferred as a regulatory asset.
Derivative instruments are subject to various credit-related losses in the event of nonperformance by counterparties to the transaction. Exchange-traded contracts are supported by the financial and credit quality of the clearing members of the respective exchanges and have nominal credit risk. In all other transactions, we are exposed to credit risk. Our credit risk management program involves establishing credit limits and collateral requirements for counterparties, using master netting arrangements or similar agreements, and reporting daily exposure to senior management.
We believe that entering into master netting arrangements or similar agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. These master netting arrangements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master netting arrangement or similar agreement level by counterparty.
The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of June 30, 2016, and December 31, 2015:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2016
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
16

 
$
2

 
$
—

 
$
14

Ameren Illinois
 
5

 
4

 
—

 
1

Ameren
 
$
21

 
$
6

 
$
—

 
$
15

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
28

 
$
2

 
$
4

 
$
22

Ameren Illinois
 
186

 
4

 
—

 
182

Ameren
 
$
214

 
$
6

 
$
4

 
$
204

2015
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
17

 
$
1

 
$
—

 
$
16

Ameren Illinois
 
1

 
—

 
—

 
1

Ameren
 
$
18

 
$
1

 
$
—

 
$
17

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
44

 
$
1

 
$
8

 
$
35

Ameren Illinois
 
220

 
—

 
3

 
217

Ameren
 
$
264

 
$
1

 
$
11

 
$
252

(a)
Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.
Concentrations of Credit Risk
In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages. We calculate maximum exposures based on the gross fair value of financial instruments, including NPNS and other accrual contracts. These exposures are calculated on a gross basis, which include affiliate exposure not eliminated at the consolidated Ameren level. The potential loss on counterparty exposures may be reduced or eliminated by the application of master netting arrangements or similar agreements and collateral held. As of June 30, 2016, if counterparty groups were to fail completely to perform on contracts, the Ameren Companies’ maximum exposure would have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held.
Derivative Instruments with Credit Risk-Related Contingent Features
Our commodity contracts contain collateral provisions tied to the Ameren Companies’ credit ratings. If we were to experience an adverse change in our credit ratings, or if a counterparty with reasonable grounds for uncertainty regarding our ability to satisfy an obligation requested adequate assurance of performance, additional collateral postings might be required. The following table presents, as of June 30, 2016, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that counterparties could require. The additional collateral required is the net liability position allowed under the master netting arrangements or similar agreements, assuming (1) the credit risk-related contingent features underlying these arrangements were triggered on June 30, 2016, and (2) those counterparties with rights to do so requested collateral.
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
2016
 
 
 
 
 
Ameren Missouri
$
74

 
$
2

 
$
66

Ameren Illinois
50

 
—

 
41

Ameren
$
124

 
$
2

 
$
107

(a)
Before consideration of master netting arrangements or similar agreements and including NPNS and other accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master netting arrangements or similar agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements.
Fair Value Measurements
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS
Fair value is defined as the price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value.
All financial assets and liabilities carried at fair value are classified and disclosed in one of three hierarchy levels. See Note 8 – Fair Value Measurements under Part II, Item 8, of the Form 10-K for information related to hierarchy levels. We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.
The following table describes the valuation techniques and unobservable inputs utilized by the Ameren Companies for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the periods ended June 30, 2016, and December 31, 2015:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
2016
 
 
 
 
 
 
 
 
Natural gas
$
—

$
(1
)
Discounted cash flow
Nodal basis ($/mmbtu)(b)
(0.80) – 0
(0.50)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.22 – 6
2
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.38
(e)
 
Power(f)
15

(170
)
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps ($/MWh)(g)
27 – 43
30
 
 
 
 
 
Estimated auction price for FTRs ($/MW)(b)
(309) – 1,509
96
 
 
 
 
 
Nodal basis ($/MWh)(g)
(9) – (1)
(2)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.56
(e)
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.38
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices ($/mmbtu)(b)
3 – 5
4
 
 
 
 
 
Escalation rate (%)(b)(h)
4
(e)
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs ($/credit)(b)
5 – 7
6
 
Uranium
—

(4
)
Option model
Volatilities (%)(b)
21
(e)
 
 
 
 
Discounted cash flow
Average forward uranium pricing ($/pound)(b)
27 – 30
29
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.38
(e)
2015
 
 
 
 
 
 
 
 
Natural gas
$
1

$
(1
)
Option model
Volatilities (%)(b)
35 – 55
45
 
 
 
 
 
Nodal basis ($/mmbtu)(c)
(0.30) – 0
(0.20)
 
 
 
 
Discounted cash flow
Nodal basis ($/mmbtu)(b)
(0.10) – 0
(0.10)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.40 – 12
7
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.40
(e)
 
Power(f)
16

(170
)
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps ($/MWh)(g)
22 – 39
29
 
 
 
 
 
Estimated auction price for FTRs ($/MW)(b)
(270) – 2,057
211
 
 
 
 
 
Nodal basis ($/MWh)(g)
(10) – (1)
(3)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.86
(e)
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.40
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices ($/mmbtu)(b)
3 – 4
4
 
 
 
 
 
Escalation rate (%)(b)(h)
3
(e)
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs ($/credit)(b)
5 – 7
6
 
Uranium
—

(1
)
Option model
Volatilities (%)(b)
20
(e)
 
 
 
 
Discounted cash flow
Average forward uranium pricing ($/pound)(b)
35 – 42
37
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.40
(e)

(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Not applicable.
(f)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2020. Valuations beyond 2020 use fundamentally modeled pricing by month for peak and off-peak demand.
(g)
The balance at Ameren is comprised of Ameren Missouri and Ameren Illinois power contracts, which respond differently to unobservable input changes due to their opposing positions.
(h)
Escalation rate applies to power prices in 2031 and beyond for June 30, 2016 and to power prices in 2026 and beyond for December 31, 2015.
In accordance with applicable authoritative accounting guidance, we consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing, as well as any potential credit enhancements, into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default derived from market data such as the price of credit default swaps, bond yields, and credit ratings. No gains or losses related to valuation adjustments for counterparty default risk were recorded at Ameren, Ameren Missouri, or Ameren Illinois in the first six months of 2016 or 2015. At June 30, 2016, and December 31, 2015, the counterparty default risk valuation adjustment related to derivative contracts was immaterial for Ameren, Ameren Missouri, and Ameren Illinois.
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2016:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
1

 
$
5

 
$
—

 
$
6

 
 
Power
 
—

 
—

 
15

 
15

 
 
Total derivative assets – commodity contracts
 
$
1

 
$
5

 
$
15

 
$
21

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
378

 
—

 
—

 
378

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
129

 
—

 
129

 
 
Corporate bonds
 
—

 
56

 
—

 
56

 
 
Other
 
—

 
16

 
—

 
16

 
 
Total nuclear decommissioning trust fund
 
$
379

 
$
201

 
$
—

 
$
580

(b) 
 
Total Ameren
 
$
380

 
$
206

 
$
15

 
$
601

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
 
Power
 
—

 
—

 
15

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
1

 
$
15

 
$
16

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
378

 
—

 
—

 
378

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
129

 
—

 
129

 
 
Corporate bonds
 
—

 
56

 
—

 
56

 
 
Other
 
—

 
16

 
—

 
16

 
 
Total nuclear decommissioning trust fund
 
$
379

 
$
201

 
$
—

 
$
580

(b) 
 
Total Ameren Missouri
 
$
379

 
$
202

 
$
15

 
$
596

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
1

 
$
4

 
$
—

 
$
5

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
14

 
$
—

 
$
—

 
$
14

 
 
Natural gas
 
—

 
25

 
1

 
26

 
 
Power
 
—

 
—

 
170

 
170

 
 
Uranium
 
—

 
—

 
4

 
4

 
 
Total Ameren
 
$
14

 
$
25

 
$
175

 
$
214

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
14

 
$
—

 
$
—

 
$
14

 
 
Natural gas
 
—

 
9

 
—

 
9

 
 
Power
 
—

 
—

 
1

 
1

 
 
Uranium
 
—

 
—

 
4

 
4

 
 
Total Ameren Missouri
 
$
14

 
$
9

 
$
5

 
$
28

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
—

 
$
16

 
$
1

 
$
17

 
 
Power
 
—

 
—

 
169

 
169

 
 
Total Ameren Illinois
 
$
—

 
$
16

 
$
170

 
$
186

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $2 million of receivables, payables, and accrued income, net.
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2015:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
1

 
$
2

 
 
Power
 
—

 
—

 
16

 
16

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
1

 
$
17

 
$
18

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
4

 
$
—

 
$
—

 
$
4

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
109

 
—

 
109

 
 
Corporate bonds
 
—

 
58

 
—

 
58

 
 
Other
 
—

 
22

 
—

 
22

 
 
Total nuclear decommissioning trust fund
 
$
368

 
$
189

 
$
—

 
$
557

(b) 
 
Total Ameren
 
$
368

 
$
190

 
$
17

 
$
575

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Natural gas
 
$
—

 
$
—

 
$
1

 
$
1

 
 
Power
 
—

 
—

 
16

 
16

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
—

 
$
17

 
$
17

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
4

 
$
—

 
$
—

 
$
4

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
109

 
—

 
109

 
 
Corporate bonds
 
—

 
58

 
—

 
58

 
 
Other
 
—

 
22

 
—

 
22

 
 
Total nuclear decommissioning trust fund
 
$
368

 
$
189

 
$
—

 
$
557

(b) 
 
Total Ameren Missouri
 
$
368

 
$
189

 
$
17

 
$
574

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
29

 
$
—

 
$
—

 
$
29

 
 
Natural gas
 
1

 
62

 
1

 
64

 
 
Power
 
—

 
—

 
170

 
170

 
 
Uranium
 
—

 
—

 
1

 
1

 
 
Total Ameren
 
$
30

 
$
62

 
$
172

 
$
264

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
29

 
$
—

 
$
—

 
$
29

 
 
Natural gas
 
—

 
13

 
1

 
14

 
 
Uranium
 
—

 
—

 
1

 
1

 
 
Total Ameren Missouri
 
$
29

 
$
13

 
$
2

 
$
44

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
1

 
$
49

 
$
—

 
$
50

 
 
Power
 
—

 
—

 
170

 
170

 
 
Total Ameren Illinois
 
$
1

 
$
49

 
$
170

 
$
220

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $(1) million of receivables, payables, and accrued income, net.
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2016:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Natural gas:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
—

$
(1
)
$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Settlements
 
—

 
1

 
1

Ending balance at June 30, 2016
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(1
)
$
(1
)
Power:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
6

$
(187
)
$
(181
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(1
)
 
14

 
13

Purchases
 
13

 
—

 
13

Settlements
 
(4
)
 
4

 
—

Ending balance at June 30, 2016
$
14

$
(169
)
$
(155
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
14

$
14

Uranium:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
(4
)
$
(a)

$
(4
)
Ending balance at June 30, 2016
$
(4
)
$
(a)

$
(4
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(a)

$
—

(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2015:
 
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(6
)
$
(a)

$
(6
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
1

 
(a)

 
1

Settlements
 
2

 
(a)

 
2

Transfers out of Level 3
 
2

 
(a)

 
2

Ending balance at June 30, 2015
$
(1
)
$
(a)

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
3

$
(a)

$
3

Natural gas:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(1
)
$
1

$
—

Purchases
 
—

 
(1
)
 
(1
)
Settlements
 
1

 
(1
)
 
—

Ending balance at June 30, 2015
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
4

$
(164
)
$
(160
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(4
)
 
(4
)
Purchases
 
29

 
—

 
29

Settlements
 
(6
)
 
3

 
(3
)
Ending balance at June 30, 2015
$
27

$
(165
)
$
(138
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
1

$
(5
)
$
(4
)
Uranium:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(1
)
 
(a)

 
(1
)
Ending balance at June 30, 2015
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
(1
)
$
(a)

$
(1
)
(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2016:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
—

$
—

$
—

Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Ending balance at June 30, 2016
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(1
)
$
(1
)
Power:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
16

$
(170
)
$
(154
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(4
)
 
(7
)
 
(11
)
Purchases
 
13

 
—

 
13

Settlements
 
(11
)
 
8

 
(3
)
Ending balance at June 30, 2016
$
14

$
(169
)
$
(155
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(5
)
$
(5
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(3
)
 
(a)

 
(3
)
Ending balance at June 30, 2016
$
(4
)
$
(a)

$
(4
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
(3
)
$
(a)

$
(3
)
(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2015:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(6
)
$
(a)

$
(6
)
Settlements
 
3

 
(a)

 
3

Transfers out of Level 3
 
2

 
(a)

 
2

Ending balance at June 30, 2015
$
(1
)
$
(a)

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(a)

$
—

Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(1
)
$
—

$
(1
)
Settlements
 
1

 
(1
)
 
—

Ending balance at June 30, 2015
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
9

$
(142
)
$
(133
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(2
)
 
(29
)
 
(31
)
Purchases
 
29

 
—

 
29

Settlements
 
(9
)
 
6

 
(3
)
Ending balance at June 30, 2015
$
27

$
(165
)
$
(138
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(29
)
$
(29
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(2
)
$
(a)

$
(2
)
Ending balance at June 30, 2015
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(a)

$
—

(a)
Not applicable.
Transfers into or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level, but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) existing assets and liabilities that were previously classified as Level 3, but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers between Level 1 and Level 3 for fuel oils were primarily caused by changes in availability of similar financial trades observable on electronic exchanges between the periods. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the three and six months ended June 30, 2016, and 2015, there were no transfers between Level 1 and Level 2 or between Level 2 and Level 3 related to derivative commodity contracts.
The Ameren Companies’ carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. They are considered to be Level 1 in the fair value hierarchy. The Ameren Companies' short-term borrowings also approximate fair value because of their short-term nature. Short-term borrowings are considered to be Level 2 in the fair value hierarchy as they are valued based on market rates for similar market transactions. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments, which fair value measurement is considered to be Level 2 in the fair value hierarchy.
The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations and preferred stock at June 30, 2016, and December 31, 2015:
 
June 30, 2016
 
December 31, 2015
 
Carrying
Amount
 
Fair
Value
 
Carrying
Amount
 
Fair
Value
Ameren:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
7,036

 
$
7,973

 
$
7,275

 
$
7,814

Preferred stock(a)
142

 
127

 
142

 
125

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,999

 
$
4,539

 
$
4,110

 
$
4,449

Preferred stock
80

 
77

 
80

 
75

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
2,343

 
$
2,692

 
$
2,471

 
$
2,665

Preferred stock
62

 
50

 
62

 
50

(a)
Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.
Related Party Transactions
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS
Ameren (parent) and its subsidiaries have engaged in, and may in the future engage in, affiliate transactions in the normal course of business. These transactions primarily consist of power purchases and sales, services received or rendered, and borrowings and lendings.
Transactions between affiliates are reported as intercompany transactions on their respective financial statements but are eliminated in consolidation for Ameren’s financial statements. For a discussion of our material related party agreements, see Note 14 – Related Party Transactions under Part II, Item 8, of the Form 10-K and the money pool arrangements discussed in Note 3 – Short-term Debt and Liquidity of this report.
Electric Power Supply Agreement
In April 2016, Ameren Illinois conducted a procurement event, administered by the IPA, to purchase energy products through May 31, 2019. Ameren Missouri was among the winning suppliers in this event. As a result, Ameren Missouri and Ameren Illinois entered into an energy product agreement by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, 375,200 megawatthours at an average price of $34.71 per megawatthour during the period of June 1, 2017, through September 30, 2018.
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the three and six months ended June 30, 2016 and 2015:
 
 
 
 
 
Three Months
 
Six Months
Agreement
Income Statement
Line Item
 
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply
Operating Revenues
 
2016
$
3

$
(a)

$
12

$
(a)

agreements with Ameren Illinois
 
 
2015
 
4

 
(a)

 
5

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2016
 
7

 
1

 
13

 
2

rent and facility services
 
 
2015
 
7

 
1

 
13

 
2

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2016
 
(b)

 
(b)

 
(b)

 
(b)

miscellaneous support services
 
 
2015
 
1

 
(b)

 
1

 
(b)

Total Operating Revenues
 
 
2016
$
10

$
1

$
25

$
2

 
 
 
2015
 
12

 
1

 
19

 
2

Ameren Illinois power supply
Purchased Power
 
2016
$
(a)

$
3

$
(a)

$
12

agreements with Ameren Missouri
 
 
2015
 
(a)

 
4

 
(a)

 
5

Ameren Illinois transmission
Purchased Power
 
2016
 
(a)

 
1

 
(a)

 
1

services with ATXI
 
 
2015
 
(a)

 
(b)

 
(a)

 
1

Total Purchased Power
 
 
2016
$
(a)

$
4

$
(a)

$
13

 
 
 
2015
 
(a)

 
4

 
(a)

 
6

Ameren Services support services
Other Operations and Maintenance
 
2016
$
32

$
30

$
66

$
61

agreement
 
 
2015
 
32

 
30

 
66

 
59

Money pool borrowings (advances)
Interest Charges/ Miscellaneous Income
 
2016
$
(b)

$
(b)

$
(b)

$
(b)

 
 
 
2015
 
(b)

 
(b)

 
(b)

 
(b)

(a)
Not applicable.
(b)
Amount less than $1 million.
Commitments And Contingencies
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES
We are involved in legal, tax and regulatory proceedings before various courts, regulatory commissions, authorities and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in the notes to our financial statements in this report and in our Form 10-K, will not have a material adverse effect on our results of operations, financial position, or liquidity.
Reference is made to Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 14 – Related Party Transactions, Note 15 – Commitments and Contingencies, and Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K. See also Note 2 – Rate and Regulatory Matters, Note 8 – Related Party Transactions, and Note 10 – Callaway Energy Center.
Callaway Energy Center
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at June 30, 2016. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year. Both coverages were renewed in 2016.
Type and Source of Coverage
Maximum  Coverages
 
Maximum Assessments
for Single Incidents
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375

  
$
—

  
Pool participation
12,986

(a) 
127

(b) 
 
$
13,361

(c) 
$
127

  
Property damage:
 
 
 
 
NEIL
$
2,750

(d) 
$
30

(e) 
European Mutual Association for Nuclear Insurance
450

(f) 
—

 
 
$
3,200

 
$
30

 
Replacement power:
 
 
 
 
NEIL
$
490

(g) 
$
7

(e) 
(a)
Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)
Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)
Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $127 million per incident for each licensed reactor it operates with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)
NEIL provides $2.75 billion in property damage, decontamination, and premature decommissioning insurance for radiation events. NEIL provides $2.3 billion in property damage for nonradiation events.
(e)
All NEIL insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)
European Mutual Association for Nuclear Insurance provides $450 million in excess of the $2.75 billion and $2.3 billion property coverage for radiation and nonradiation events, respectively, provided by NEIL.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first twelve weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $328 million.
The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The most recent five-year inflationary adjustment became effective in September 2013. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.
Losses resulting from terrorist attacks on nuclear facilities are covered under NEIL’s insurance policies, subject to an industrywide aggregate policy limit of $3.24 billion within a 12-month period, or $1.83 billion for events not involving radiation contamination.
If losses from a nuclear incident at the Callaway energy center exceed the limits of, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.
Other Obligations
To supply a portion of the fuel requirements of Ameren Missouri’s energy centers, Ameren Missouri has entered into various long-term commitments for the procurement of coal, natural gas, nuclear fuel, and methane gas. Additionally, Ameren Missouri and Ameren Illinois have entered into various long-term commitments for purchased power and natural gas for distribution. At June 30, 2016, total obligations related to commitments for coal, natural gas, nuclear fuel, purchased power, methane gas, equipment, and meter reading services, among other agreements, at Ameren, Ameren Missouri, and Ameren Illinois were $4,465 million, $2,614 million, and $1,790 million, respectively. For additional information regarding our obligations and commitments at December 31, 2015, see Note 15 – Commitments and Contingencies under Part II, Item 8 of the Form 10-K.
In April 2016, Ameren Illinois conducted a procurement event, administered by the IPA, to purchase energy products through May 31, 2019. In this event, Ameren Illinois contracted to purchase approximately 3,609,800 megawatthours of energy products for $105 million from June 1, 2016, through May 31, 2019. See Note 8 – Related Party Transactions for additional information regarding the energy product agreement between Ameren Missouri and Ameren Illinois as a result of this procurement event.
Environmental Matters
We are subject to various environmental laws and regulations enforced by federal, state, and local authorities. Such requirements can impact the siting, development and operation of new and existing generation, transmission, distribution and natural gas storage facilities. Such requirements can encompass emissions, discharges to water, water usage, impacts to air, land, and water, and chemical and waste handling. Complex and lengthy approval processes are required to obtain, modify or renew permits and licenses for new or existing facilities. Additionally, the use and handling of various chemicals or hazardous materials at some of our facilities require release prevention plans and emergency response procedures.
The EPA has promulgated several environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be costly for Ameren Missouri, which operates coal-fired power plants. Significant new rules include the regulation of CO2 emissions from existing power plants through the Clean Power Plan and from new power plants through the revised NSPS; the CSAPR, which requires further reductions of SO2 emissions and NOx emissions from power plants; a regulation governing management and storage of CCR; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from power plants; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to wastewater discharges from power plants; and new regulations under the Clean Water Act that could require significant capital expenditures, such as modifications to water intake structures at Ameren Missouri’s energy centers. The EPA also periodically reviews and revises national ambient air quality standards, including those standards associated with emissions from power plants, such as particulate matter, ozone, SO2 and NOx. Certain of these new regulations are being or are likely to be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of future regulations are unknown, the individual or combined effects of new environmental regulations could result in significant capital expenditures and increased operating costs for Ameren and Ameren Missouri. Compliance with all of these environmental laws and regulations could be prohibitively expensive, result in the closure or alteration of the operation of some of Ameren Missouri’s energy centers, or require capital investment. Ameren and Ameren Missouri expect that these costs would be recoverable through rates, subject to MoPSC prudence review, but the nature and timing of costs and their recovery could result in regulatory lag.
Ameren Missouri's current plan for compliance with existing environmental regulations for air emissions includes burning ultra-low-sulfur coal and installing new or optimizing existing pollution control equipment. Ameren and Ameren Missouri estimate that they will need to make capital expenditures of $600 million to $700 million in the aggregate from 2016 through 2020 in order to comply with existing environmental regulations. Additionally, Ameren Missouri may be required to install additional air emissions controls within the next six to 10 years. This estimate includes capital expenditures required for the CCR regulations, the Clean Water Act rule applicable to cooling water intake structures at existing power plants, and the Clean Water Act effluent limitation guidelines applicable to steam electric generating units, all of which are discussed below. These estimates do not include the potential impacts of the Clean Power Plan discussed below. The actual amount of capital expenditures required to comply with existing environmental regulations may vary substantially from the above estimate due to uncertainty as to the precise compliance strategies that will be used and their ultimate cost, among other things.
The following sections describe the more significant new environmental laws and rules and environmental enforcement and remediation matters that affect or could affect our operations.
Clean Air Act
Federal and state laws require significant reductions in SO2 and NOx through either emission source reductions or the use and retirement of emission allowances. The first phase of the CSAPR emission reduction requirements became effective in 2015 and the second phase of emission reduction requirements will become effective in 2017; additional emission reduction requirements may apply in subsequent years. To achieve compliance with the CSAPR, Ameren Missouri burns ultra-low-sulfur coal, operates two scrubbers at its Sioux energy center, and optimizes other existing pollution control equipment. Ameren Missouri does not expect to make additional capital investments to comply with the current CSAPR requirements. However, Ameren Missouri expects to incur additional costs to lower its emissions at one or more of its energy centers to comply with the CSAPR in future years. These higher costs are expected to be recovered from customers through the FAC or higher base rates.
CO2 Emissions Standards
The Clean Power Plan, which sets forth CO2 emissions standards applicable to existing power plants, was issued by the EPA in August 2015 but stayed by the United States Supreme Court in February 2016, pending the outcome of various appeals, as discussed below.
If upheld, the Clean Power Plan would require Missouri and Illinois to reduce CO2 emissions from power plants within their states significantly below 2005 levels by 2030. The rule contains interim compliance periods commencing in 2022 that would require each state to demonstrate progress in achieving its CO2 reduction target. Ameren continues to evaluate the Clean Power Plan's potential impacts to its operations, including those related to electric system reliability, and to its level of investment in customer energy efficiency programs, renewable energy, and other forms of generation. Significant uncertainty exists regarding the impact of the Clean Power Plan, as its implementation will depend upon plans to be developed by the states. Numerous legal challenges are pending, which could result in the rule being declared invalid or the nature and timing of CO2 emissions reductions being revised. All implementation requirements are deferred until such time as these legal challenges are concluded. A decision by the District of Columbia Circuit Court of Appeals is expected to be issued in the fourth quarter of 2016 or the first quarter of 2017, and subsequent appeals to the United States Supreme Court are likely. We cannot predict the outcome of such legal challenges or their impact on our results of operations, financial position, or liquidity. If the rule is ultimately upheld and implemented in substantially similar form to the rule when issued, compliance measures could result in the closure or alteration of the operation of some of Ameren Missouri’s coal and natural-gas-fired energy centers, which could result in increased operating costs and require Ameren Missouri to make new or accelerated capital expenditures. Ameren Missouri expects substantially all of these increased costs to be recoverable, subject to MoPSC prudence review, through higher rates to customers, which could be significant.
In 2015, the EPA also issued final regulations that set CO2 emissions standards for new power plants. These new standards establish separate emissions limits for new natural-gas-fired combined cycle plants and new coal-fired plants.
Federal and state legislation or regulations that mandate limits on the emission of CO2 may result in significant increases in capital expenditures and operating costs, which could lead to increased liquidity needs and higher financing costs. Mandatory limits on the emission of CO2 could increase costs for Ameren Missouri’s customers or have a material adverse effect on Ameren's and Ameren Missouri's results of operations, financial position, and liquidity if regulators delay or deny recovery in rates of these compliance costs. The cost of Ameren Illinois’ purchased power and gas purchased for resale could increase. However, Ameren Illinois expects these costs would be recovered from customers with no material adverse effect on its results of operations, financial position, or liquidity. Ameren's and Ameren Missouri's earnings might benefit from increased investment to comply with CO2 emission limitations to the extent that the investments are reflected and recovered on a timely basis in rates charged to customers.
NSR and Clean Air Litigation
In January 2011, the Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri. The EPA's complaint, as amended in October 2013, alleges that in performing projects at its Rush Island coal-fired energy center in 2007 and 2010, Ameren Missouri violated provisions of the Clean Air Act and Missouri law. Ameren Missouri anticipates that a trial of this case will begin in August 2016. Ameren Missouri believes its defenses are meritorious and is defending itself vigorously. However, there can be no assurances that it will be successful in its efforts.
The ultimate resolution of this matter could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri. A resolution of this matter could result in increased capital expenditures for the installation of pollution control equipment and increased operations and maintenance expenses. We are unable to predict the ultimate resolution of these matters or the costs that might be incurred.
Clean Water Act
In 2014, the EPA issued its final rule applicable to cooling water intake structures at existing power plants. The rule requires a case-by-case evaluation and plan for reducing aquatic organisms impinged on the facility’s intake screens or entrained through the plant's cooling water system. Additionally, in 2015, the EPA issued its final rule to revise the effluent limitation guidelines applicable to steam electric generating units. Effluent limitation guidelines are national standards for water discharges that are based on the effectiveness of available control technology. The EPA's rule prohibits effluent discharges of certain waste streams and imposes more stringent limitations on certain components in water discharges from power plants. All of Ameren Missouri’s coal-fired and nuclear energy centers are subject to the cooling water intake structures rule and all of Ameren Missouri’s coal-fired energy centers are subject to the effluent limitations rule. Implementation of both rules will occur during the renewal process of each energy center’s water discharge permits, which will occur between 2018 and 2023. The rules could have an adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity if their implementation requires extensive modifications to the cooling water systems and water discharge systems at Ameren Missouri’s energy centers and if those investments are not recovered on a timely basis in electric rates charged to Ameren Missouri’s customers.
Ash Management
In 2015, the EPA issued regulations regarding the management and disposal of CCR. These regulations will affect CCR disposal and handling costs at Ameren Missouri's energy centers. The regulations allow for the management of CCR as a solid waste, as well as for its continued beneficial uses, such as recycling, which could reduce the amount to be disposed. The regulations also establish criteria regarding the structural integrity, location, and operation of CCR impoundments and landfills. They require groundwater monitoring, and closure of impoundments if the groundwater standards are not achieved. Ameren Missouri's capital expenditure plan includes the cost of constructing landfills as part of its environmental compliance plan.
The new regulations do not apply to ash ponds at plants no longer in operation, such as Ameren’s Meredosia and Hutsonville energy centers.
Remediation
The Ameren Companies are involved in a number of remediation actions to clean up sites impacted by the use or disposal of materials containing hazardous substances. Federal and state laws can require responsible parties to fund remediation actions regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. Ameren Missouri and Ameren Illinois have each been identified by federal or state governments as a potentially responsible party at several contaminated sites.
As of June 30, 2016, Ameren Illinois owned or was otherwise responsible for 44 former MGP sites in Illinois, which are in various stages of investigation, evaluation, remediation, and closure. Ameren Illinois estimates it could substantially conclude remediation efforts by 2025. The ICC allows Ameren Illinois to recover remediation and litigation costs associated with its former MGP sites from its electric and natural gas utility customers through environmental adjustment rate riders. Costs are subject to annual review by the ICC. As of June 30, 2016, Ameren Illinois estimated the obligation related to these former MGP sites at $217 million to $306 million. Ameren and Ameren Illinois recorded a liability of $217 million to represent the estimated minimum obligation for these sites, as no other amount within the range was a better estimate.
The scope and extent to which these former MGP sites are remediated may increase as remediation efforts continue. Considerable uncertainty remains in these estimates because many site-specific factors can influence the ultimate actual costs, including unanticipated underground structures, the degree to which groundwater is encountered, regulatory changes, local ordinances, and site accessibility. The actual costs may vary substantially from these estimates.
Ameren Illinois is also responsible for the cleanup of some underground storage tanks and a water treatment plant in Illinois. As of June 30, 2016, Ameren Illinois recorded a liability of $0.7 million to represent its best estimate of its obligation for these sites.
In 2008, the EPA issued an administrative order to three companies, including Ameren Missouri, to conduct a site investigation at a former coal tar distillery in St. Louis, Missouri. While Ameren Missouri is the current owner of the site, it did not conduct any of the manufacturing operations involving coal tar or its byproducts. Site investigation activities and studies are complete, and reports have been submitted to the EPA for review. Based upon the results of those studies, it is unlikely that further remediation will be required. Accordingly, as of June 30, 2016, Ameren Missouri did not record a liability for remediation at this site.
Ameren Missouri also participated in the investigation of various sites known as Sauget Area 2 located in Sauget, Illinois. In 2000, the EPA notified Ameren Missouri and numerous other companies, including Solutia, Inc., that former landfills and lagoons at those sites may contain soil and groundwater contamination. From about 1926 until 1976, Ameren Missouri operated an energy center adjacent to Sauget Area 2. Ameren Missouri currently owns a parcel of property at Sauget Area 2 that was once used by others as a landfill.
In December 2013, the EPA issued its record of decision for Sauget Area 2 approving the investigation and the remediation actions recommended by the potentially responsible parties. Further negotiation among the potentially responsible parties will determine how to fund the implementation of the EPA-approved cleanup remedies. As of June 30, 2016, Ameren Missouri estimated its obligation related to Sauget Area 2 at $1 million to $2.5 million. Ameren Missouri recorded a liability of $1 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate.
In December 2012, Ameren Missouri signed an administrative order with the EPA and agreed to investigate soil and groundwater conditions at an Ameren Missouri-owned substation in St. Charles, Missouri. As of June 30, 2016, Ameren Missouri estimated and recorded a $0.6 million liability related to the site. Although monitoring will continue for some time, no significant remediation measures are anticipated.
Our operations or those of our predecessor companies involve the use of, disposal of, and in appropriate circumstances, the cleanup of substances regulated under environmental laws. We are unable to determine whether such practices will result in future environmental commitments or will affect our results of operations, financial position, or liquidity.
Ameren Missouri Municipal Taxes
The cities of Creve Coeur and Winchester, Missouri, on behalf of themselves and other municipalities in Ameren Missouri’s service area, filed a class action lawsuit in November 2011, against Ameren Missouri in the Circuit Court of St. Louis County, Missouri. The lawsuit alleges that Ameren Missouri failed to collect and pay gross receipts taxes or license fees on certain revenues, including revenues from wholesale power and interchange sales. Ameren and Ameren Missouri recorded immaterial liabilities on their respective balance sheets as of June 30, 2016 and December 31, 2015, representing their estimate of the probable taxes and fees due as a result of this lawsuit. Ameren Missouri believes there is a remote possibility that a liability relating to this lawsuit could be material to Ameren and Ameren Missouri’s results of operations, financial position, and liquidity. Ameren Missouri believes its defenses are meritorious and is defending itself vigorously. However, there can be no assurances that Ameren Missouri will be successful in its efforts.
Callaway Energy Center
CALLAWAY ENERGY CENTER
CALLAWAY ENERGY CENTER
Under the NWPA, the DOE is responsible for disposing of spent nuclear fuel from the Callaway energy center and other commercial nuclear energy centers. Under the NWPA, Ameren and other utilities that own and operate those energy centers are responsible for paying the disposal costs. The NWPA established the fee that these utilities pay the federal government for disposing of the spent nuclear fuel at one mill, or one-tenth of one cent, for each kilowatthour generated and sold by those plants. The NWPA also requires the DOE to review the nuclear waste fee annually against the cost of the nuclear waste disposal program and to propose to the United States Congress any fee adjustment necessary to offset the costs of the program. As required by the NWPA, Ameren Missouri and other utilities have entered into standard contracts with the DOE. Consistent with the NWPA and its standard contract, Ameren Missouri had historically collected one mill from its electric customers for each kilowatthour of electricity that it generated and sold from its Callaway energy center. Because the federal government is not meeting its disposal obligation, the collection of this fee has been suspended since May 2014.
Although both the NWPA and the standard contract stated that the DOE would begin to dispose of spent nuclear fuel by 1998, the DOE is not meeting its disposal obligation. The DOE's delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway energy center is not expected to adversely affect the continued operations of the energy center.
As a result of the DOE's failure to begin to dispose of spent nuclear fuel from commercial nuclear energy centers and fulfill its contractual obligations, Ameren Missouri and other nuclear energy center owners sued the DOE to recover costs, such as certain NRC fees and ad valorem taxes, incurred for ongoing storage of their spent fuel. The lawsuit resulted in a settlement agreement that provides for annual recovery of additional spent fuel storage and related costs. Ameren Missouri will continue to apply for reimbursement from the DOE for allowable costs associated with the ongoing storage of spent fuel.
Electric utility rates charged to customers provide for the recovery of the Callaway energy center's decommissioning costs, which include decontamination, dismantling, and site restoration costs, over the expected life of the nuclear energy center. Amounts collected from customers are deposited into the external nuclear decommissioning trust fund to provide for the Callaway energy center’s decommissioning. It is assumed that the Callaway energy center site will be decommissioned through the immediate dismantlement method and removed from service. Ameren and Ameren Missouri have recorded an ARO for the Callaway energy center decommissioning costs at fair value, which represents the present value of estimated future cash outflows. Annual decommissioning costs of $7 million are included in the costs used to establish electric rates for Ameren Missouri's customers. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway energy center. In April 2016, the MoPSC approved no change in electric service rates for decommissioning costs based on Ameren Missouri’s updated cost study and funding analysis filed in April 2015.
The fair value of the trust fund for Ameren Missouri's Callaway energy center is reported as "Nuclear decommissioning trust fund" in Ameren's and Ameren Missouri's balance sheets. This amount is legally restricted and may be used only to fund the costs of nuclear decommissioning. Changes in the fair value of the trust fund are recorded as an increase or decrease to the nuclear decommissioning trust fund, with an offsetting adjustment to the related regulatory liability. If the assumed return on trust assets is not earned, Ameren Missouri believes that it is probable that any such earnings deficiency will be recovered in rates.
Retirement Benefits
RETIREMENT BENEFITS
RETIREMENT BENEFITS
The following table presents the components of the net periodic benefit cost (benefit) incurred for Ameren’s pension and postretirement benefit plans for the three and six months ended June 30, 2016 and 2015:
  
Pension Benefits
 
Postretirement Benefits
 
 
Three Months
 
Six Months
 
Three Months
 
Six Months
 
  
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
Service cost
$
20

 
$
22

 
$
40

 
$
46

 
$
5

 
$
6

 
$
10

 
$
11

 
Interest cost
45

 
43

 
92

 
87

 
12

 
12

 
24

 
24

 
Expected return on plan assets
(63
)
 
(62
)
 
(126
)
 
(124
)
 
(18
)
 
(17
)
 
(36
)
 
(34
)
 
Amortization of:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Prior service benefit
—

 
—

 
—

 
—

 
(1
)
 
(1
)
 
(2
)
 
(2
)
 
Actuarial loss (gain)
7

 
19

 
16

 
37

 
(2
)
 
2

 
(5
)
 
3

 
Settlement loss
—

 
1

 
—

 
1

 
—

 
—

 
—

 
—

 
Net periodic benefit cost (benefit)
$
9

 
$
23

 
$
22

 
$
47

 
$
(4
)
 
$
2

 
$
(9
)
 
$
2

 

Ameren Missouri and Ameren Illinois are responsible for their respective shares of Ameren’s pension and postretirement costs. The following table presents the pension costs and the postretirement benefit costs (benefit) incurred for the three and six months ended June 30, 2016 and 2015:
  
Pension Benefits
 
Postretirement Benefits
 
 
Three Months
 
Six Months
 
Three Months
 
Six Months
 
  
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
Ameren Missouri(a)
$
5

 
$
13

 
$
13

 
$
28

 
$
(1
)
 
$
3

 
$
(2
)
 
$
4

 
Ameren Illinois
6

 
10

 
11

 
19

 
(3
)
 
(1
)
 
(7
)
 
(2
)
 
Other
(2
)
 
—

 
(2
)
 
—

 
—

 
—

 
—

 
—

 
Ameren(a)(b)
$
9

 
$
23

 
$
22

 
$
47

 
$
(4
)
 
$
2

 
$
(9
)
 
$
2

 

(a)
Does not include the impact of the regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates.
(b)
Includes amounts for Ameren registrants and nonregistrant subsidiaries.
Divestiture Transactions and Discontinued Operations
DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
DISCONTINUED OPERATIONS
See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of the Form 10-K for additional information related to discontinued operations.
All matters related to the final tax basis of New AER and the related tax benefit resulting from the divested merchant generation business were resolved with the completion of the IRS audit for 2013. During the second quarter of 2015, based on the completion of the IRS audit, Ameren removed a reserve for unrecognized tax benefits recorded in 2013 and recognized a tax benefit from discontinued operations. 
The following table presents the components of discontinued operations in Ameren's consolidated statement of income for the three and six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Operating revenues
$
—

 
$
—

 
$
—

 
$
—

 
Operating benefits (expenses)
—

 
—

 
—

 
3

 
Operating income before income tax
—

 
—

 
—

 
3

 
Income tax benefit
—

 
52

 
—

 
49

 
Income from discontinued operations, net of taxes
$
—

 
$
52

 
$
—

 
$
52

 
The following table presents the carrying amounts of the components of assets and liabilities of Ameren’s discontinued operations, which consist primarily of AROs and related deferred income tax assets associated with the abandoned Meredosia and Hutsonville energy centers, at June 30, 2016, and December 31, 2015:
 
June 30, 2016
 
December 31, 2015
Assets of discontinued operations
 
 
 
Accumulated deferred income taxes, net
$
14

 
$
14

Total assets of discontinued operations
$
14

 
$
14

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
1

 
$
1

Asset retirement obligations(a)
26

 
28

Total liabilities of discontinued operations
$
27

 
$
29

(a)
Ameren has demolished and completed its retirement obligations at the Hutsonville energy center. The remaining ARO liabilities relate to the abandoned Meredosia energy center.
Segment Information
SEGMENT INFORMATION
SEGMENT INFORMATION
Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. Ameren Missouri and Ameren Illinois each have one reportable segment. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all of the operations of Ameren Missouri’s business as described in Note 1 – Summary of Significant Accounting Policies. The Ameren Illinois segment for both Ameren and Ameren Illinois includes all of the operations of Ameren Illinois’ business as described in Note 1 – Summary of Significant Accounting Policies. The category called Other primarily includes Ameren parent company activities, Ameren Services, and ATXI.
The following table presents information about the reported revenues and net income attributable to Ameren common shareholders from continuing operations for the three and six months ended June 30, 2016 and 2015, and total assets of continuing operations as of June 30, 2016, and December 31, 2015:
Three Months
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Ameren
 
2016
 
 
 
 
 
 
 
 
 
 
External revenues
$
857

 
$
541

 
$
29

  
$
—

 
$
1,427

 
Intersegment revenues
10

 
1

 
1

  
(12
)
 
—

 
Net income attributable to Ameren common shareholders from continuing operations
92

 
45

 
10

 
—

 
147

 
2015
 
 
 
 
 
 
 
 
 
 
External revenues
$
872

 
$
512

 
$
17

 
$
—

 
$
1,401

 
Intersegment revenues
12

 
1

 
—

 
(13
)
 
—

 
Net income attributable to Ameren common shareholders from continuing operations
61

 
31

 
6

 
—

 
98

 
Six Months
  
 
  
 
  
 
  
 
  
 
2016
 
 
 
 
 
 
 
 
 
 
External revenues
$
1,583

 
$
1,217

 
$
61

 
$
—

 
$
2,861

 
Intersegment revenues
25

 
2

 
1

 
(28
)
 
—

 
Net income attributable to Ameren common stockholders from continuing operations
106

 
104

 
42

 
—

 
252

 
2015
 
 
 
 
 
 
 
 
 
 
External revenues
$
1,665

 
$
1,256

 
$
36

 
$
—

 
$
2,957

 
Intersegment revenues
19

 
2

 
1

 
(22
)
 
—

 
Net income (loss) attributable to Ameren common stockholders from continuing operations
102

 
84

 
20

 
—

 
206

 
As of June 30, 2016:
 
 
 
 
 
 
 
 
 
 
Total assets
$
13,649

 
$
8,999

 
$
1,276

 
$
(145
)
 
$
23,779

(a) 
As of December 31, 2015:
 
 
 
 
 
 
 
 
 
 
Total assets
$
13,851

 
$
8,903

 
$
1,139

 
$
(267
)
 
$
23,626

(a) 
(a)    Excludes total assets from discontinued operations of $14 million as of June 30, 2016, and December 31, 2015.
Summary Of Significant Accounting Policies (Policies)
Consolidation 
Ameren’s financial statements are prepared on a consolidated basis and therefore include the accounts of its majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Missouri and Ameren Illinois have no subsidiaries, and therefore their financial statements are not prepared on a consolidated basis. All tabular dollar amounts are in millions, unless otherwise indicated.
Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair statement of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates. The results of operations of an interim period may not give a true indication of results that may be expected for a full year. These financial statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K.
Excise Taxes 
Excise taxes are levied on Ameren Missouri’s electric and natural gas businesses and on Ameren Illinois’ natural gas business and are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes for electric service in Illinois are levied on the customer and are therefore not included in Ameren Illinois’ revenues and expenses.
Earnings Per Share 
There were no material differences between Ameren’s basic and diluted earnings per share amounts for the six months ended June 30, 2016 and 2015. The assumed settlement of dilutive performance share units had an immaterial impact on earnings per share. The calculation of diluted earnings per share reflected the adoption of FASB guidance related to employee share-based payment accounting discussed below.
Accounting and Reporting Developments 
Below is a summary of recently issued authoritative accounting standards relevant to the Ameren Companies.
Revenue from Contracts with Customers
In May 2014, the FASB issued authoritative accounting guidance that changes the criteria for recognizing revenue from a contract with a customer. The underlying principle of the guidance is that an entity will recognize revenue for the transfer of promised goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. The guidance also requires additional disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. Entities can apply the guidance retrospectively to each reporting period presented or retrospectively by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impact of this guidance on their results of operations, financial position, and disclosures, including their accounting for contributions in aid of construction and similar arrangements, as well as the transition method that they will use to adopt the guidance. The guidance will be effective for the Ameren Companies in the first quarter of 2018.
Amendments to the Consolidation Analysis
In February 2015, the FASB issued authoritative accounting guidance that amends the consolidation analysis for variable interest entities and voting interest entities. The new guidance affects (1) limited partnerships, similar legal entities, and certain investment funds, (2) the evaluation of fees paid to a decision maker or service provider as a variable interest, (3) how fee arrangements impact the primary beneficiary determination, and (4) the evaluation of related party relationships on the primary beneficiary determination. The adoption of this guidance in the first quarter of 2016 did not impact the Ameren Companies’ results of operations, financial position, liquidity, or disclosures.
Leases
In February 2016, the FASB issued authoritative accounting guidance that will require an entity to recognize assets and liabilities arising from a lease. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease will depend primarily on its classification as a finance or operating lease. The guidance also requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. The guidance will be effective for the Ameren Companies in the first quarter of 2019 with an option for entities to adopt early. Upon adoption, the Ameren Companies will recognize and measure operating leases on their respective balance sheets at the beginning of the earliest period presented. The Ameren Companies are currently assessing the impact of this guidance on their results of operations, financial position, statement of cash flows, and disclosures.
Improvements to Employee Share-Based Payment Accounting
In March 2016, the FASB issued authoritative accounting guidance that simplifies the accounting for share-based payment transactions, including the income tax consequences, the calculation of diluted earnings per share, the treatment of forfeitures, the classification of awards as either equity or liabilities, and the classification on the statement of cash flows. Ameren determines for each performance share unit award whether the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes results in either an excess tax benefit or an excess tax deficit. Previously, excess tax benefits were recognized in "Other paid-in capital" on Ameren’s consolidated balance sheet, and in certain cases, excess tax deficits were recognized in “Income taxes” on Ameren’s consolidated income statement. The new guidance increases income statement volatility by requiring all excess tax benefits and deficits to be recognized in “Income taxes,” and treated as discrete items in the period in which they occur. Ameren adopted this guidance in the first quarter of 2016 and prospectively applied the amendment in this guidance requiring recognition of excess tax benefits and deficits in the income statement, which resulted in recognition of a $21 million income tax benefit and a corresponding $21 million increase in income from continuing operations and net income (9 cents per diluted share) during the period. Also as a result of the adoption of this guidance, Ameren made an accounting policy election to continue to estimate the number of forfeitures expected to occur. The amendments in the guidance that require application using a modified retrospective transition method did not impact Ameren. Therefore, there was no cumulative-effect adjustment to retained earnings recognized as of January 1, 2016. Ameren applied the amendments in this guidance relating to classification on the statement of cash flows retrospectively. As a result, for the six months ended June 30, 2015, Ameren reclassified, for comparison purposes, $2 million of excess tax benefits on the statement of cash flows from financing to operating activity, and $12 million of employee payroll taxes related to share-based payments from operating to financing activity.
Derivative Financial Instruments Derivative Financial Instruments (Policies)
Derivatives
•
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
•
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
•
actual cash outlays for the purchase of these commodities that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.
Summary Of Significant Accounting Policies (Tables)
Summary Of Nonvested Shares Related To Long-Term Incentive Plan 
A summary of nonvested performance share units at June 30, 2016, and changes during the six months ended June 30, 2016, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below:
 
Performance Share Units
 
Share Units
 
Weighted-average Fair Value per Share Unit
Nonvested at January 1, 2016
1,024,870

 
$
46.08

Granted(a)
584,312

 
44.13

Forfeitures
(15,949
)
 
45.07

Vested(b)
(10,754
)
 
43.44

Nonvested at June 30, 2016
1,582,479

 
$
45.39

(a)
Performance share units granted to certain executive and nonexecutive officers and other eligible employees under the 2014 Incentive Plan.
(b)
Performance share units vested due to the attainment of retirement eligibility by certain employees. Actual shares issued for retirement-eligible employees will vary depending on actual performance over the three-year measurement period.
Schedule of Excise Taxes 
The following table presents excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas” and “Operating Expenses – Taxes other than income taxes” for the three and six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
2016
 
2015
 
2016
 
2015
Ameren Missouri
$
40

 
$
41

 
$
70

 
$
75

Ameren Illinois
11

 
10

 
31

 
33

Ameren
$
51

 
$
51

 
$
101

 
$
108

Short-Term Debt And Liquidity Short-Term Debt and Liquidity (Tables)
Schedule of Short-term Debt
The following table presents commercial paper outstanding as of June 30, 2016, and December 31, 2015:
  
June 30, 2016
 
December 31, 2015
Ameren (parent)
$
524

 
$
301

Ameren Missouri
77

 
—

Ameren Illinois
177

 
—

Ameren Consolidated
$
778

 
$
301

The following table summarizes the borrowing activity and relevant interest rates under Ameren’s (parent), Ameren Missouri’s, and Ameren Illinois’ commercial paper programs for the six months ended June 30, 2016 and 2015:
 
 
Ameren
(parent)
Ameren
Missouri
Ameren
Illinois
Ameren Consolidated
2016
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
402

 
$
117

$
12

$
531

Weighted-average interest rate
 
0.82
%
 
0.74
%
0.79
%
0.80
%
Peak commercial paper during period(a)
 
$
549

 
$
208

$
177

$
839

Peak interest rate
 
0.95
%
 
0.85
%
0.85
%
0.95
%
2015
 
 
 
 
 
 
Average daily commercial paper outstanding
 
$
754

 
$
84

$
5

$
843

Weighted-average interest rate
 
0.57
%
 
0.50
%
0.44
%
0.56
%
Peak commercial paper during period(a)
 
$
849

 
$
294

$
39

$
1,108

Peak interest rate
 
0.70
%
 
0.60
%
0.60
%
0.70
%

(a)
The timing of peak commercial paper issuances varies by company; therefore, the peak amounts presented by company might not equal the Ameren Consolidated peak commercial paper issuances for the period.
Long-Term Debt And Equity Financings (Tables)
Schedule Of Coverage Ratios
Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures, credit facilities, and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions, but would restrict the companies’ ability to issue first mortgage bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and first mortgage bonds and preferred stock issuable as of June 30, 2016, at an assumed annual interest rate of 5% and dividend rate of 6%.
 
 
Required Interest
Coverage Ratio(a)
 
Actual Interest
Coverage Ratio
 
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
 
Actual Dividend
Coverage Ratio
 
Preferred Stock
Issuable
 
Ameren Missouri
 
≥2.0
 
4.7
$
3,793
 
≥2.5
 
105.4
$
2,346
 
Ameren Illinois
 
≥2.0
 
6.9
 
3,827
(d) 
≥1.5
 
2.8
 
203
(e) 
(a)
Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.
(b)
Amount of first mortgage bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include first mortgage bonds issuable based on retired bond capacity of $1,206 million and $279 million at Ameren Missouri and Ameren Illinois, respectively.
(c)
Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.
(d)
Amount of first mortgage bonds issuable by Ameren Illinois based on unfunded property additions and retired bonds solely under the former IP mortgage indenture. The amount of first mortgage bonds issuable by Ameren Illinois is also subject to the lien restrictions contained in the Illinois Credit Agreement.
(e)
Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.
Other Income and Expenses (Tables)
Other Income And Expenses
The following table presents the components of “Other Income and Expenses” in the Ameren Companies’ statements of income for the six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Ameren:(a)
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
5

 
$
6

 
$
13

 
$
11

 
Interest income on industrial development revenue bonds
6

 
6

 
13

 
13

 
Interest income
4

 
4

 
8

 
8

 
Other
1

 
—

 
2

 
3

 
Total miscellaneous income
$
16

 
$
16

 
$
36

 
$
35

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
2

 
$
2

 
$
7

 
$
10

 
Other
4

 
4

 
6

 
7

 
Total miscellaneous expense
$
6

 
$
6

 
$
13

 
$
17

 
Ameren Missouri:
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
3

 
$
5

 
$
10

 
$
9

 
Interest income on industrial development revenue bonds
6

 
6

 
13

 
13

 
Interest income
—

 
1

 
—

 
1

 
Other
—

 
—

 
1

  
—

 
Total miscellaneous income
$
9

 
$
12

 
$
24

 
$
23

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
1

 
$
1

 
$
2

 
$
3

 
Other
1

 
1

 
2

 
2

 
Total miscellaneous expense
$
2

 
$
2

 
$
4

 
$
5

 
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Ameren Illinois:
 
 
 
 
 
 
 
 
Miscellaneous income:
 
 
 
 
 
 
 
 
Allowance for equity funds used during construction
$
2

 
$
1

 
$
3

 
$
2

 
Interest income
3

 
3

 
7

 
7

 
Other
1

 
—

 
1

 
2

 
Total miscellaneous income
$
6

 
$
4

 
$
11

 
$
11

 
Miscellaneous expense:
 
 
 
 
 
 
 
 
Donations
$
1

 
$
1

 
$
5

 
$
4

 
Other
2

 
1

 
3

 
3

 
Total miscellaneous expense
$
3

 
$
2

 
$
8

 
$
7

 
(a)
Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Derivative Financial Instruments (Tables)
Open Gross Derivative Volumes By Commodity Type 
The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of June 30, 2016, and December 31, 2015. As of June 30, 2016, these contracts extended through October 2018, March 2021, May 2032, and January 2019 for fuel oils, natural gas, power, and uranium, respectively.
  
Quantity (in millions, except as indicated)
 
2016
2015
Commodity
Ameren Missouri
Ameren Illinois
Ameren
Ameren Missouri
Ameren Illinois
Ameren
Fuel oils (in gallons)(a)
24

(b)

24

35

(b)

35

Natural gas (in mmbtu)
30

131

161

30

151

181

Power (in megawatthours)
1

10

11

1

10

11

Uranium (pounds in thousands)
395

(b)

395

494

(b)

494

(a)
Consists of ultra-low-sulfur diesel products.
(b)
Not applicable.
Derivative Instruments Carrying Value 
The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of June 30, 2016, and December 31, 2015:
 
Balance Sheet Location
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
2016
 
 
 
 
 
 
Natural gas
Other current assets
 
$
—

 
$
2

 
$
2

 
Other assets
 
1

 
3

 
4

Power
Other current assets
 
15

 
—

 
15

 
Total assets (a)
 
$
16

 
$
5

 
$
21

Fuel oils
Other current liabilities
 
$
12

 
$
—

 
$
12

 
Other deferred credits and liabilities
 
2

 
—

 
2

Natural gas
MTM derivative liabilities
 
(b)

 
11

 
(b)

 
Other current liabilities
 
3

 
—

 
14

 
Other deferred credits and liabilities
 
6

 
6

 
12

Power
MTM derivative liabilities
 
(b)

 
12

 
(b)

 
Other current liabilities
 
1

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
157

 
157

Uranium
Other current liabilities
 
1

 
—

 
1

 
Other deferred credits and liabilities
 
3

 
—

 
3

 
Total liabilities (c)
 
$
28

 
$
186

 
$
214

2015
 
 
 
 
 
 
Natural gas
Other current assets
 
$
—

 
$
1

 
$
1

 
Other assets
 
1

 
—

 
1

Power
Other current assets
 
16

 
—

 
16

 
Total assets (a)
 
$
17

 
$
1

 
$
18

Fuel oils
Other current liabilities
 
$
22

 
$
—

 
$
22

 
Other deferred credits and liabilities
 
7

 
—

 
7

Natural gas
MTM derivative liabilities
 
(b)

 
32

 
(b)

 
Other current liabilities
 
6

 
—

 
38

 
Other deferred credits and liabilities
 
8

 
18

 
26

Power
MTM derivative liabilities
 
(b)

 
13

 
(b)

 
Other current liabilities
 
—

 
—

 
13

 
Other deferred credits and liabilities
 
—

 
157

 
157

Uranium
Other current liabilities
 
1

 
—

 
1

 
Total liabilities (c)
 
$
44

 
$
220

 
$
264


(a)
Because all contracts qualifying for hedge accounting receive regulatory deferral, the cumulative amount of pretax net gains on all derivative instruments is deferred as a regulatory liability.
(b)
Balance sheet line item not applicable to registrant.
(c)
Because all contracts qualifying for hedge accounting receive regulatory deferral, the cumulative amount of pretax net losses on all derivative instruments is deferred as a regulatory asset.
Offsetting Derivative Assets and Liabilities 
The following table provides the recognized gross derivative balances and the net amounts of those derivatives subject to an enforceable master netting arrangement or similar agreement as of June 30, 2016, and December 31, 2015:
 
 
 
 
Gross Amounts Not Offset in the Balance Sheet
 
 
Commodity Contracts Eligible to be Offset
 
Gross Amounts Recognized in the Balance Sheet
 
Derivative Instruments
 
Cash Collateral Received/Posted(a)
 
Net
Amount
2016
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
16

 
$
2

 
$
—

 
$
14

Ameren Illinois
 
5

 
4

 
—

 
1

Ameren
 
$
21

 
$
6

 
$
—

 
$
15

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
28

 
$
2

 
$
4

 
$
22

Ameren Illinois
 
186

 
4

 
—

 
182

Ameren
 
$
214

 
$
6

 
$
4

 
$
204

2015
 
 
 
 
 
 
 
 
Assets:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
17

 
$
1

 
$
—

 
$
16

Ameren Illinois
 
1

 
—

 
—

 
1

Ameren
 
$
18

 
$
1

 
$
—

 
$
17

Liabilities:
 
 
 
 
 
 
 
 
Ameren Missouri
 
$
44

 
$
1

 
$
8

 
$
35

Ameren Illinois
 
220

 
—

 
3

 
217

Ameren
 
$
264

 
$
1

 
$
11

 
$
252

(a)
Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.
Derivative Instruments With Credit Risk-Related Contingent Features 
The following table presents, as of June 30, 2016, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that counterparties could require. The additional collateral required is the net liability position allowed under the master netting arrangements or similar agreements, assuming (1) the credit risk-related contingent features underlying these arrangements were triggered on June 30, 2016, and (2) those counterparties with rights to do so requested collateral.
 
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
2016
 
 
 
 
 
Ameren Missouri
$
74

 
$
2

 
$
66

Ameren Illinois
50

 
—

 
41

Ameren
$
124

 
$
2

 
$
107

(a)
Before consideration of master netting arrangements or similar agreements and including NPNS and other accrual contract exposures.
(b)
As collateral requirements with certain counterparties are based on master netting arrangements or similar agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements.
Fair Value Measurements (Tables)
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques 
The following table describes the valuation techniques and unobservable inputs utilized by the Ameren Companies for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the periods ended June 30, 2016, and December 31, 2015:
 
 
Fair Value
 
 
 
Weighted Average
 
 
Assets
Liabilities
Valuation Technique(s)
Unobservable Input
Range
Level 3 Derivative asset and liability – commodity contracts(a):
 
 
 
2016
 
 
 
 
 
 
 
 
Natural gas
$
—

$
(1
)
Discounted cash flow
Nodal basis ($/mmbtu)(b)
(0.80) – 0
(0.50)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.22 – 6
2
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.38
(e)
 
Power(f)
15

(170
)
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps ($/MWh)(g)
27 – 43
30
 
 
 
 
 
Estimated auction price for FTRs ($/MW)(b)
(309) – 1,509
96
 
 
 
 
 
Nodal basis ($/MWh)(g)
(9) – (1)
(2)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.56
(e)
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.38
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices ($/mmbtu)(b)
3 – 5
4
 
 
 
 
 
Escalation rate (%)(b)(h)
4
(e)
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs ($/credit)(b)
5 – 7
6
 
Uranium
—

(4
)
Option model
Volatilities (%)(b)
21
(e)
 
 
 
 
Discounted cash flow
Average forward uranium pricing ($/pound)(b)
27 – 30
29
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.38
(e)
2015
 
 
 
 
 
 
 
 
Natural gas
$
1

$
(1
)
Option model
Volatilities (%)(b)
35 – 55
45
 
 
 
 
 
Nodal basis ($/mmbtu)(c)
(0.30) – 0
(0.20)
 
 
 
 
Discounted cash flow
Nodal basis ($/mmbtu)(b)
(0.10) – 0
(0.10)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.40 – 12
7
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.40
(e)
 
Power(f)
16

(170
)
Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps ($/MWh)(g)
22 – 39
29
 
 
 
 
 
Estimated auction price for FTRs ($/MW)(b)
(270) – 2,057
211
 
 
 
 
 
Nodal basis ($/MWh)(g)
(10) – (1)
(3)
 
 
 
 
 
Counterparty credit risk (%)(c)(d)
0.86
(e)
 
 
 
 
 
Ameren Illinois credit risk (%)(c)(d)
0.40
(e)
 
 
 
 
Fundamental energy production model
Estimated future gas prices ($/mmbtu)(b)
3 – 4
4
 
 
 
 
 
Escalation rate (%)(b)(h)
3
(e)
 
 
 
 
Contract price allocation
Estimated renewable energy credit costs ($/credit)(b)
5 – 7
6
 
Uranium
—

(1
)
Option model
Volatilities (%)(b)
20
(e)
 
 
 
 
Discounted cash flow
Average forward uranium pricing ($/pound)(b)
35 – 42
37
 
 
 
 
 
Ameren Missouri credit risk (%)(c)(d)
0.40
(e)

(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)
Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)
Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)
Not applicable.
(f)
Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2020. Valuations beyond 2020 use fundamentally modeled pricing by month for peak and off-peak demand.
(g)
The balance at Ameren is comprised of Ameren Missouri and Ameren Illinois power contracts, which respond differently to unobservable input changes due to their opposing positions.
(h)
Escalation rate applies to power prices in 2031 and beyond for June 30, 2016 and to power prices in 2026 and beyond for December 31, 2015.
Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis 
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of June 30, 2016:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
1

 
$
5

 
$
—

 
$
6

 
 
Power
 
—

 
—

 
15

 
15

 
 
Total derivative assets – commodity contracts
 
$
1

 
$
5

 
$
15

 
$
21

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
378

 
—

 
—

 
378

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
129

 
—

 
129

 
 
Corporate bonds
 
—

 
56

 
—

 
56

 
 
Other
 
—

 
16

 
—

 
16

 
 
Total nuclear decommissioning trust fund
 
$
379

 
$
201

 
$
—

 
$
580

(b) 
 
Total Ameren
 
$
380

 
$
206

 
$
15

 
$
601

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
 
Power
 
—

 
—

 
15

 
15

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
1

 
$
15

 
$
16

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
1

 
$
—

 
$
—

 
$
1

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
378

 
—

 
—

 
378

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
129

 
—

 
129

 
 
Corporate bonds
 
—

 
56

 
—

 
56

 
 
Other
 
—

 
16

 
—

 
16

 
 
Total nuclear decommissioning trust fund
 
$
379

 
$
201

 
$
—

 
$
580

(b) 
 
Total Ameren Missouri
 
$
379

 
$
202

 
$
15

 
$
596

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
1

 
$
4

 
$
—

 
$
5

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
14

 
$
—

 
$
—

 
$
14

 
 
Natural gas
 
—

 
25

 
1

 
26

 
 
Power
 
—

 
—

 
170

 
170

 
 
Uranium
 
—

 
—

 
4

 
4

 
 
Total Ameren
 
$
14

 
$
25

 
$
175

 
$
214

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
14

 
$
—

 
$
—

 
$
14

 
 
Natural gas
 
—

 
9

 
—

 
9

 
 
Power
 
—

 
—

 
1

 
1

 
 
Uranium
 
—

 
—

 
4

 
4

 
 
Total Ameren Missouri
 
$
14

 
$
9

 
$
5

 
$
28

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
—

 
$
16

 
$
1

 
$
17

 
 
Power
 
—

 
—

 
169

 
169

 
 
Total Ameren Illinois
 
$
—

 
$
16

 
$
170

 
$
186

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $2 million of receivables, payables, and accrued income, net.
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 2015:
 
 
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 
Total
 
Assets:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Natural gas
 
$
—

 
$
1

 
$
1

 
$
2

 
 
Power
 
—

 
—

 
16

 
16

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
1

 
$
17

 
$
18

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
4

 
$
—

 
$
—

 
$
4

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
109

 
—

 
109

 
 
Corporate bonds
 
—

 
58

 
—

 
58

 
 
Other
 
—

 
22

 
—

 
22

 
 
Total nuclear decommissioning trust fund
 
$
368

 
$
189

 
$
—

 
$
557

(b) 
 
Total Ameren
 
$
368

 
$
190

 
$
17

 
$
575

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Natural gas
 
$
—

 
$
—

 
$
1

 
$
1

 
 
Power
 
—

 
—

 
16

 
16

 
 
Total derivative assets – commodity contracts
 
$
—

 
$
—

 
$
17

 
$
17

 
 
Nuclear decommissioning trust fund:
 
 
 
 
 
 
 
 
 
 
Cash and cash equivalents
 
$
4

 
$
—

 
$
—

 
$
4

 
 
Equity securities:
 
 
 
 
 
 
 
 
 
 
U.S. large capitalization
 
364

 
—

 
—

 
364

 
 
Debt securities:
 
 
 
 
 
 
 
 
 
 
U.S. treasury and agency securities
 
—

 
109

 
—

 
109

 
 
Corporate bonds
 
—

 
58

 
—

 
58

 
 
Other
 
—

 
22

 
—

 
22

 
 
Total nuclear decommissioning trust fund
 
$
368

 
$
189

 
$
—

 
$
557

(b) 
 
Total Ameren Missouri
 
$
368

 
$
189

 
$
17

 
$
574

 
Ameren
Derivative assets – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
—

 
$
1

 
$
—

 
$
1

 
Liabilities:
 
 
 
 
 
 
 
 
 
 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
 
Fuel oils
 
$
29

 
$
—

 
$
—

 
$
29

 
 
Natural gas
 
1

 
62

 
1

 
64

 
 
Power
 
—

 
—

 
170

 
170

 
 
Uranium
 
—

 
—

 
1

 
1

 
 
Total Ameren
 
$
30

 
$
62

 
$
172

 
$
264

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Missouri
Fuel oils
 
$
29

 
$
—

 
$
—

 
$
29

 
 
Natural gas
 
—

 
13

 
1

 
14

 
 
Uranium
 
—

 
—

 
1

 
1

 
 
Total Ameren Missouri
 
$
29

 
$
13

 
$
2

 
$
44

 
Ameren
Derivative liabilities – commodity contracts(a):
 
 
 
 
 
 
 
 
 
Illinois
Natural gas
 
$
1

 
$
49

 
$
—

 
$
50

 
 
Power
 
—

 
—

 
170

 
170

 
 
Total Ameren Illinois
 
$
1

 
$
49

 
$
170

 
$
220

 
(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)
Balance excludes $(1) million of receivables, payables, and accrued income, net.
Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level Three In The Fair Value Hierarchy 
The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2016:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Natural gas:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
—

$
(1
)
$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Settlements
 
—

 
1

 
1

Ending balance at June 30, 2016
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(1
)
$
(1
)
Power:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
6

$
(187
)
$
(181
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(1
)
 
14

 
13

Purchases
 
13

 
—

 
13

Settlements
 
(4
)
 
4

 
—

Ending balance at June 30, 2016
$
14

$
(169
)
$
(155
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
14

$
14

Uranium:
 
 
 
 
 
 
Beginning balance at April 1, 2016
$
(4
)
$
(a)

$
(4
)
Ending balance at June 30, 2016
$
(4
)
$
(a)

$
(4
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(a)

$
—

(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the three months ended June 30, 2015:
 
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(6
)
$
(a)

$
(6
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
1

 
(a)

 
1

Settlements
 
2

 
(a)

 
2

Transfers out of Level 3
 
2

 
(a)

 
2

Ending balance at June 30, 2015
$
(1
)
$
(a)

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
3

$
(a)

$
3

Natural gas:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(1
)
$
1

$
—

Purchases
 
—

 
(1
)
 
(1
)
Settlements
 
1

 
(1
)
 
—

Ending balance at June 30, 2015
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
4

$
(164
)
$
(160
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(4
)
 
(4
)
Purchases
 
29

 
—

 
29

Settlements
 
(6
)
 
3

 
(3
)
Ending balance at June 30, 2015
$
27

$
(165
)
$
(138
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
1

$
(5
)
$
(4
)
Uranium:
 
 
 
 
 
 
Beginning balance at April 1, 2015
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(1
)
 
(a)

 
(1
)
Ending balance at June 30, 2015
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
(1
)
$
(a)

$
(1
)
(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2016:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
—

$
—

$
—

Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
—

 
(1
)
 
(1
)
Ending balance at June 30, 2016
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(1
)
$
(1
)
Power:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
16

$
(170
)
$
(154
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(4
)
 
(7
)
 
(11
)
Purchases
 
13

 
—

 
13

Settlements
 
(11
)
 
8

 
(3
)
Ending balance at June 30, 2016
$
14

$
(169
)
$
(155
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
—

$
(5
)
$
(5
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2016
$
(1
)
$
(a)

$
(1
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(3
)
 
(a)

 
(3
)
Ending balance at June 30, 2016
$
(4
)
$
(a)

$
(4
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2016
$
(3
)
$
(a)

$
(3
)
(a)
Not applicable.

The following table summarizes the changes in the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the six months ended June 30, 2015:
  
 
Net derivative commodity contracts
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Fuel oils:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(6
)
$
(a)

$
(6
)
Settlements
 
3

 
(a)

 
3

Transfers out of Level 3
 
2

 
(a)

 
2

Ending balance at June 30, 2015
$
(1
)
$
(a)

$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(a)

$
—

Natural gas:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(1
)
$
—

$
(1
)
Settlements
 
1

 
(1
)
 
—

Ending balance at June 30, 2015
$
—

$
(1
)
$
(1
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
—

$
—

Power:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
9

$
(142
)
$
(133
)
Realized and unrealized gains (losses) included in regulatory assets/liabilities
 
(2
)
 
(29
)
 
(31
)
Purchases
 
29

 
—

 
29

Settlements
 
(9
)
 
6

 
(3
)
Ending balance at June 30, 2015
$
27

$
(165
)
$
(138
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(29
)
$
(29
)
Uranium:
 
 
 
 
 
 
Beginning balance at January 1, 2015
$
(2
)
$
(a)

$
(2
)
Ending balance at June 30, 2015
$
(2
)
$
(a)

$
(2
)
Change in unrealized gains (losses) related to assets/liabilities held at June 30, 2015
$
—

$
(a)

$
—

(a)
Not applicable.
Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt, Capital Lease Obligations And Preferred Stock 
The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations and preferred stock at June 30, 2016, and December 31, 2015:
 
June 30, 2016
 
December 31, 2015
 
Carrying
Amount
 
Fair
Value
 
Carrying
Amount
 
Fair
Value
Ameren:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
7,036

 
$
7,973

 
$
7,275

 
$
7,814

Preferred stock(a)
142

 
127

 
142

 
125

Ameren Missouri:
 
 
 
 
 
 
 
Long-term debt and capital lease obligations (including current portion)
$
3,999

 
$
4,539

 
$
4,110

 
$
4,449

Preferred stock
80

 
77

 
80

 
75

Ameren Illinois:
 
 
 
 
 
 
 
Long-term debt (including current portion)
$
2,343

 
$
2,692

 
$
2,471

 
$
2,665

Preferred stock
62

 
50

 
62

 
50

(a)
Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.
Related Party Transactions (Tables)
Schedule of Related Party Transactions
The following table presents the impact on Ameren Missouri and Ameren Illinois of related party transactions for the three and six months ended June 30, 2016 and 2015:
 
 
 
 
 
Three Months
 
Six Months
Agreement
Income Statement
Line Item
 
 
 
Ameren
Missouri
 
Ameren
Illinois
 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply
Operating Revenues
 
2016
$
3

$
(a)

$
12

$
(a)

agreements with Ameren Illinois
 
 
2015
 
4

 
(a)

 
5

 
(a)

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2016
 
7

 
1

 
13

 
2

rent and facility services
 
 
2015
 
7

 
1

 
13

 
2

Ameren Missouri and Ameren Illinois
Operating Revenues
 
2016
 
(b)

 
(b)

 
(b)

 
(b)

miscellaneous support services
 
 
2015
 
1

 
(b)

 
1

 
(b)

Total Operating Revenues
 
 
2016
$
10

$
1

$
25

$
2

 
 
 
2015
 
12

 
1

 
19

 
2

Ameren Illinois power supply
Purchased Power
 
2016
$
(a)

$
3

$
(a)

$
12

agreements with Ameren Missouri
 
 
2015
 
(a)

 
4

 
(a)

 
5

Ameren Illinois transmission
Purchased Power
 
2016
 
(a)

 
1

 
(a)

 
1

services with ATXI
 
 
2015
 
(a)

 
(b)

 
(a)

 
1

Total Purchased Power
 
 
2016
$
(a)

$
4

$
(a)

$
13

 
 
 
2015
 
(a)

 
4

 
(a)

 
6

Ameren Services support services
Other Operations and Maintenance
 
2016
$
32

$
30

$
66

$
61

agreement
 
 
2015
 
32

 
30

 
66

 
59

Money pool borrowings (advances)
Interest Charges/ Miscellaneous Income
 
2016
$
(b)

$
(b)

$
(b)

$
(b)

 
 
 
2015
 
(b)

 
(b)

 
(b)

 
(b)

(a)
Not applicable.
(b)
Amount less than $1 million.
Commitments And Contingencies (Tables)
Schedule of Insurance Coverage at Callaway Energy Center
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at June 30, 2016. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year. Both coverages were renewed in 2016.
Type and Source of Coverage
Maximum  Coverages
 
Maximum Assessments
for Single Incidents
 
Public liability and nuclear worker liability:
 
 
 
 
American Nuclear Insurers
$
375

  
$
—

  
Pool participation
12,986

(a) 
127

(b) 
 
$
13,361

(c) 
$
127

  
Property damage:
 
 
 
 
NEIL
$
2,750

(d) 
$
30

(e) 
European Mutual Association for Nuclear Insurance
450

(f) 
—

 
 
$
3,200

 
$
30

 
Replacement power:
 
 
 
 
NEIL
$
490

(g) 
$
7

(e) 
(a)
Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)
Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)
Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $127 million per incident for each licensed reactor it operates with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)
NEIL provides $2.75 billion in property damage, decontamination, and premature decommissioning insurance for radiation events. NEIL provides $2.3 billion in property damage for nonradiation events.
(e)
All NEIL insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)
European Mutual Association for Nuclear Insurance provides $450 million in excess of the $2.75 billion and $2.3 billion property coverage for radiation and nonradiation events, respectively, provided by NEIL.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first twelve weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $328 million.
Retirement Benefits (Tables)
Components Of Net Periodic Benefit Cost 
The following table presents the components of the net periodic benefit cost (benefit) incurred for Ameren’s pension and postretirement benefit plans for the three and six months ended June 30, 2016 and 2015:
  
Pension Benefits
 
Postretirement Benefits
 
 
Three Months
 
Six Months
 
Three Months
 
Six Months
 
  
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
Service cost
$
20

 
$
22

 
$
40

 
$
46

 
$
5

 
$
6

 
$
10

 
$
11

 
Interest cost
45

 
43

 
92

 
87

 
12

 
12

 
24

 
24

 
Expected return on plan assets
(63
)
 
(62
)
 
(126
)
 
(124
)
 
(18
)
 
(17
)
 
(36
)
 
(34
)
 
Amortization of:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Prior service benefit
—

 
—

 
—

 
—

 
(1
)
 
(1
)
 
(2
)
 
(2
)
 
Actuarial loss (gain)
7

 
19

 
16

 
37

 
(2
)
 
2

 
(5
)
 
3

 
Settlement loss
—

 
1

 
—

 
1

 
—

 
—

 
—

 
—

 
Net periodic benefit cost (benefit)
$
9

 
$
23

 
$
22

 
$
47

 
$
(4
)
 
$
2

 
$
(9
)
 
$
2

 

Summary Of Benefit Plan Costs Incurred 
Ameren Missouri and Ameren Illinois are responsible for their respective shares of Ameren’s pension and postretirement costs. The following table presents the pension costs and the postretirement benefit costs (benefit) incurred for the three and six months ended June 30, 2016 and 2015:
  
Pension Benefits
 
Postretirement Benefits
 
 
Three Months
 
Six Months
 
Three Months
 
Six Months
 
  
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
2016
 
2015
 
Ameren Missouri(a)
$
5

 
$
13

 
$
13

 
$
28

 
$
(1
)
 
$
3

 
$
(2
)
 
$
4

 
Ameren Illinois
6

 
10

 
11

 
19

 
(3
)
 
(1
)
 
(7
)
 
(2
)
 
Other
(2
)
 
—

 
(2
)
 
—

 
—

 
—

 
—

 
—

 
Ameren(a)(b)
$
9

 
$
23

 
$
22

 
$
47

 
$
(4
)
 
$
2

 
$
(9
)
 
$
2

 

(a)
Does not include the impact of the regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs included in rates.
(b)
Includes amounts for Ameren registrants and nonregistrant subsidiaries.
Divestiture Transactions and Discontinued Operations Divestiture Transactions and Discontinued Operations (Tables)
Schedule of Disposal Groups, Including Discontinued Operations Income Staement, balance Sheet and Additional Disclosures
The following table presents the components of discontinued operations in Ameren's consolidated statement of income for the three and six months ended June 30, 2016 and 2015:
 
Three Months
 
Six Months
 
 
2016
 
2015
 
2016
 
2015
 
Operating revenues
$
—

 
$
—

 
$
—

 
$
—

 
Operating benefits (expenses)
—

 
—

 
—

 
3

 
Operating income before income tax
—

 
—

 
—

 
3

 
Income tax benefit
—

 
52

 
—

 
49

 
Income from discontinued operations, net of taxes
$
—

 
$
52

 
$
—

 
$
52

 
The following table presents the carrying amounts of the components of assets and liabilities of Ameren’s discontinued operations, which consist primarily of AROs and related deferred income tax assets associated with the abandoned Meredosia and Hutsonville energy centers, at June 30, 2016, and December 31, 2015:
 
June 30, 2016
 
December 31, 2015
Assets of discontinued operations
 
 
 
Accumulated deferred income taxes, net
$
14

 
$
14

Total assets of discontinued operations
$
14

 
$
14

Liabilities of discontinued operations
 
 
 
Accounts payable and other current obligations
$
1

 
$
1

Asset retirement obligations(a)
26

 
28

Total liabilities of discontinued operations
$
27

 
$
29

(a)
Ameren has demolished and completed its retirement obligations at the Hutsonville energy center. The remaining ARO liabilities relate to the abandoned Meredosia energy center.
Segment Information (Tables)
Schedule Of Segment Reporting Information By Segment
The following table presents information about the reported revenues and net income attributable to Ameren common shareholders from continuing operations for the three and six months ended June 30, 2016 and 2015, and total assets of continuing operations as of June 30, 2016, and December 31, 2015:
Three Months
Ameren
Missouri
 
Ameren
Illinois
 
Other
 
Intersegment
Eliminations
 
Ameren
 
2016
 
 
 
 
 
 
 
 
 
 
External revenues
$
857

 
$
541

 
$
29

  
$
—

 
$
1,427

 
Intersegment revenues
10

 
1

 
1

  
(12
)
 
—

 
Net income attributable to Ameren common shareholders from continuing operations
92

 
45

 
10

 
—

 
147

 
2015
 
 
 
 
 
 
 
 
 
 
External revenues
$
872

 
$
512

 
$
17

 
$
—

 
$
1,401

 
Intersegment revenues
12

 
1

 
—

 
(13
)
 
—

 
Net income attributable to Ameren common shareholders from continuing operations
61

 
31

 
6

 
—

 
98

 
Six Months
  
 
  
 
  
 
  
 
  
 
2016
 
 
 
 
 
 
 
 
 
 
External revenues
$
1,583

 
$
1,217

 
$
61

 
$
—

 
$
2,861

 
Intersegment revenues
25

 
2

 
1

 
(28
)
 
—

 
Net income attributable to Ameren common stockholders from continuing operations
106

 
104

 
42

 
—

 
252

 
2015
 
 
 
 
 
 
 
 
 
 
External revenues
$
1,665

 
$
1,256

 
$
36

 
$
—

 
$
2,957

 
Intersegment revenues
19

 
2

 
1

 
(22
)
 
—

 
Net income (loss) attributable to Ameren common stockholders from continuing operations
102

 
84

 
20

 
—

 
206

 
As of June 30, 2016:
 
 
 
 
 
 
 
 
 
 
Total assets
$
13,649

 
$
8,999

 
$
1,276

 
$
(145
)
 
$
23,779

(a) 
As of December 31, 2015:
 
 
 
 
 
 
 
 
 
 
Total assets
$
13,851

 
$
8,903

 
$
1,139

 
$
(267
)
 
$
23,626

(a) 
(a)    Excludes total assets from discontinued operations of $14 million as of June 30, 2016, and December 31, 2015.
Summary Of Significant Accounting Policies (Narrative) (Detail) (USD $)
In Millions, except Per Share data, unless otherwise specified
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Basis Of Presentation And Significant Accounting Policies [Line Items]
 
 
Income Tax Expense (Benefit)
$ 21 
 
Adjustments related to Income Tax Benefit from Share-Based payment per diluted share
$ 0.09 
 
Excess Tax Benefit from Share-based Compensation, Operating Activities
 
2 
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense
$ 32 
$ 12 
Summary Of Significant Accounting Policies (Schedule Of Excise Taxes) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Accounting Policies [Line Items]
 
 
 
 
Excise tax expense
$ 51 
$ 51 
$ 101 
$ 108 
Union Electric Company
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
Excise tax expense
40 
41 
70 
75 
Ameren Illinois Company
 
 
 
 
Accounting Policies [Line Items]
 
 
 
 
Excise tax expense
$ 11 
$ 10 
$ 31 
$ 33 
Rate And Regulatory Matters (Narrative-Missouri) (Detail) (USD $)
6 Months Ended 12 Months Ended 3 Months Ended
Jun. 30, 2016
Electric Distribution
Union Electric Company
MEEIA
Jun. 30, 2016
Mark Twain Project
Ameren Transmission Company of Illinois
mi
Dec. 31, 2015
Noranda [Member]
Union Electric Company
MWh
Sep. 30, 2016
Subsequent Event
Noranda [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Return on Rate Base [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Pending Rate Case
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Depreciation Expense [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Property Taxes [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Customer Sales Volumes [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Transmission Charges [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Pension and Other Post-Employment Benefit Plan Expenses [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Solar Rebate Expenses [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Net Energy Costs [Member]
Electric Distribution
Union Electric Company
Sep. 30, 2016
Subsequent Event
Components of Rate Increase - Income Taxes [Member]
Electric Distribution
Union Electric Company
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Public Utilities, Requested Rate Increase (Decrease), Amount
 
 
 
 
$ 25,000,000 
$ 206,000,000 
$ 74,000,000 
$ 39,000,000 
$ 10,000,000 
$ 51,000,000 
$ 34,000,000 
$ 24,000,000 
$ 15,000,000 
$ 23,000,000 
$ 15,000,000 
Public Utilities, Requested Return on Equity, Percentage
 
 
 
 
 
9.90% 
 
 
 
 
 
 
 
 
 
Public Utilities, Requested Equity Capital Structure, Percentage
 
 
 
 
 
51.80% 
 
 
 
 
 
 
 
 
 
Rate Base
 
 
 
 
 
7,200,000,000 
 
 
 
 
 
 
 
 
 
Plant Additions to Rate Base
 
 
 
 
 
1,400,000,000 
 
 
 
 
 
 
 
 
 
Regulatory Asset, Amortization Period
 
 
 
10 years 
 
 
 
 
 
 
 
 
 
 
 
Revenue Requirement
 
 
78,000,000 
81,000,000 
 
 
 
 
 
 
 
 
 
 
 
Number of Months to complete MoPSC Electric Service Proceeding
 
 
 
 
 
11 months 
 
 
 
 
 
 
 
 
 
Noranda Annual Megawatthours
 
 
4,200,000.0 
 
 
 
 
 
 
 
 
 
 
 
 
Noranda Operating Capacity
 
 
100.00% 
 
 
 
 
 
 
 
 
 
 
 
 
Noranda Summer Base Rate
 
 
45.78 
 
 
 
 
 
 
 
 
 
 
 
 
Noranda Winter Base Rate
 
 
31.11 
 
 
 
 
 
 
 
 
 
 
 
 
Incentive Award if Energy Efficiency Goals Are Achieved
$ 19,000,000 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Achieved Percentage of Energy Efficiency Earnings For Incentive Award
100.00% 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Incentive Award if Energy Efficiency Goals Are Achieved, Period of Recognition
3 years 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Transmission Line Miles
 
95 
 
 
 
 
 
 
 
 
 
 
 
 
 
Rate And Regulatory Matters (Narrative-Illinois) (Detail) (USD $)
In Millions, unless otherwise specified
1 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Jun. 30, 2016
Ameren Illinois Company
Dec. 31, 2015
Ameren Illinois Company
Jun. 30, 2016
2016 IEIMA Revenue Requirement Reconciliation
IEIMA
Ameren Illinois Company
Electric Distribution
Jun. 30, 2016
2015 IEIMA Revenue Requirement Reconciliation
IEIMA
Ameren Illinois Company
Electric Distribution
Jun. 30, 2016
2014 IEIMA Revenue Requirement Reconciliation
IEIMA
Ameren Illinois Company
Electric Distribution
Dec. 31, 2015
2014 IEIMA Revenue Requirement Reconciliation
IEIMA
Ameren Illinois Company
Electric Distribution
Apr. 30, 2016
Pending Rate Case
IEIMA
Ameren Illinois Company
Electric Distribution
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
Regulatory assets
$ 1,330 
$ 1,382 
$ 786 
$ 771 
$ 12 
$ 66 
 
 
 
Current regulatory assets
146 
260 
98 
167 
 
 
58 
103 
 
Public Utilities, Requested Rate Increase (Decrease), Amount
 
 
 
 
 
 
 
 
$ 14 
Rate And Regulatory Matters (Narrative-Federal) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 6 Months Ended 12 Months Ended 1 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Jun. 30, 2015
New Nuclear Energy Center COL [Member]
Jun. 30, 2016
Ameren Illinois Company
Dec. 31, 2015
Ameren Illinois Company
Jun. 30, 2016
Union Electric Company
Jun. 30, 2015
Union Electric Company
Jun. 30, 2016
Union Electric Company
Jun. 30, 2015
Union Electric Company
Dec. 31, 2015
Union Electric Company
Jun. 30, 2015
Union Electric Company
New Nuclear Energy Center COL [Member]
Jun. 30, 2016
Midwest Independent Transmission System Operator, Inc
Administrative Law Judge [Member]
Dec. 31, 2015
Midwest Independent Transmission System Operator, Inc
Administrative Law Judge [Member]
Feb. 28, 2015
Midwest Independent Transmission System Operator, Inc
Pending Ferc Case
Jun. 30, 2016
Midwest Independent Transmission System Operator, Inc
Pending Ferc Case
Jun. 30, 2016
Midwest Independent Transmission System Operator, Inc
Pending Ferc Case
Ameren Illinois Company
Rate And Regulatory Matters [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Public Utilities, Approved Return on Equity, Percentage
 
 
 
 
 
 
 
 
 
 
 
 
 
 
9.70% 
10.32% 
 
12.38% 
 
Customer Requested Rate on Equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
8.67% 
9.15% 
 
Current regulatory liabilities
$ 99 
 
$ 99 
 
$ 80 
 
$ 59 
$ 39 
$ 21 
 
$ 21 
 
$ 28 
 
 
 
 
$ 58 
$ 39 
Incentive adder to FERC allowed base return on common equity
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
0.50% 
 
Investments in Power and Distribution Projects
 
 
 
 
 
 
 
 
 
 
 
 
 
69 
 
 
 
 
 
Provision for Callaway construction and operating license
$ 0 
$ 69 
$ 0 
$ 69 
 
$ 69 
 
 
$ 0 
$ 69 
$ 0 
$ 69 
 
$ 69 
 
 
 
 
 
Short-Term Debt And Liquidity (Narrative) (Detail) (USD $)
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Utilities
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Short Term Debt, Weighted Average Interest Rate During Period
0.60% 
0.08% 
0.54% 
0.08% 
Credit Agreements 2012
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Line of credit facility, maximum borrowing capacity
$ 1,300,000,000 
 
$ 1,300,000,000 
 
Actual debt-to-capital ratio
0.52 
 
0.52 
 
Line of Credit Facility, Covenant Terms, Default Provision, Maximum Indebtedness
$ 75,000,000 
 
$ 75,000,000 
 
Credit Agreements 2012 |
Maximum
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Actual debt-to-capital ratio
0.65 
 
0.65 
 
Interest Coverage Requirement
200.00% 
 
200.00% 
 
Credit Agreements 2012 |
Union Electric Company |
Maximum
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Actual debt-to-capital ratio
0.65 
 
0.65 
 
Credit Agreements 2012 |
Ameren Illinois Company |
Maximum
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Actual debt-to-capital ratio
0.65 
 
0.65 
 
Missouri Credit Agreement 2012 |
Union Electric Company
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Actual debt-to-capital ratio
0.49 
 
0.49 
 
Illinois Credit Agreement 2012 |
Ameren Illinois Company
 
 
 
 
Line of Credit Facility [Line Items]
 
 
 
 
Actual debt-to-capital ratio
0.47 
 
0.47 
 
Short-Term Debt And Liquidity Short-Term Debt and Liquidity (Commercial Paper outstanding) (Details) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
$ 778 
$ 301 
Ameren (parent)
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
524 
301 
Union Electric Company
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
77 
0 
Ameren Illinois Company
 
 
Line of Credit Facility [Line Items]
 
 
Commercial paper outstanding
$ 177 
$ 0 
Short-Term Debt And Liquidity Short-Term Debt and Liquidity (Commercial Paper) (Details) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
$ 531 
$ 843 
Weighted Average Interest Rate
0.80% 
0.56% 
Peak Short Term Borrowings
839 1
1,108 1
Peak Short Term Borrowings Interest Rate
0.95% 
0.70% 
Ameren (parent)
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
402 
754 
Weighted Average Interest Rate
0.82% 
0.57% 
Peak Short Term Borrowings
549 1
849 1
Peak Short Term Borrowings Interest Rate
0.95% 
0.70% 
Union Electric Company
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
117 
84 
Weighted Average Interest Rate
0.74% 
0.50% 
Peak Short Term Borrowings
208 1
294 1
Peak Short Term Borrowings Interest Rate
0.85% 
0.60% 
Ameren Illinois Company
 
 
Line of Credit Facility [Line Items]
 
 
Average Daily Commercial Paper Borrowings Outstanding
12 
5 
Weighted Average Interest Rate
0.79% 
0.44% 
Peak Short Term Borrowings
$ 177 1
$ 39 1
Peak Short Term Borrowings Interest Rate
0.85% 
0.60% 
Long-Term Debt And Equity Financings (Narrative) (Detail) (USD $)
6 Months Ended
Jun. 30, 2016
Long-Term Debt And Equity Financings [Line Items]
 
Debt Default Provision Excess
$ 25,000,000 
Ameren Missouri And Ameren Illinois
 
Long-Term Debt And Equity Financings [Line Items]
 
Assumed interest rate
5.00% 
Dividend rate
6.00% 
Secured Debt |
Senior Secured Notes540 Due2016 [Member] |
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Debt Instrument, Interest Rate, Stated Percentage
5.40% 
Repayments of Other Long-term Debt
260,000,000 
Secured Debt |
Senior Secured Notes, 3.65%, Due 2045 [Member] |
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Debt Instrument, Face Amount
150,000,000 
Debt Instrument, Interest Rate, Stated Percentage
3.65% 
Proceeds from Issuance of Secured Debt
148,000,000 
Secured Debt |
Senior Secured Notes620 Due2016 [Member] |
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Debt Instrument, Interest Rate, Stated Percentage
6.20% 
Repayments of Other Long-term Debt
54,000,000 
Secured Debt |
Senior Secured Notes625 Due2016 [Member] |
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Debt Instrument, Interest Rate, Stated Percentage
6.25% 
Repayments of Other Long-term Debt
$ 75,000,000 
Federal Energy Regulatory Commission Restriction [Member] |
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Common stock equity to total capitalization
51.00% 
Federal Energy Regulatory Commission Restriction [Member] |
Ameren Illinois Company |
Minimum
 
Long-Term Debt And Equity Financings [Line Items]
 
Common stock equity to total capitalization
30.00% 
Long-Term Debt And Equity Financings (Schedule Of Covered Ratio) (Detail) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2016
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Bonds Issuable
$ 3,793 1
Preferred Stock Issuable
2,346 
Retired bond capacity
1,206 
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Bonds Issuable
3,827 1 2
Preferred Stock Issuable
203 3
Retired bond capacity
$ 279 
Minimum Required Ratio [Member] |
Minimum |
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
2.0 4
Dividend Coverage Ratio
2.5 5
Minimum Required Ratio [Member] |
Minimum |
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
2.0 4
Dividend Coverage Ratio
1.5 5
Actual Ratio [Member] |
Union Electric Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
4.7 
Dividend Coverage Ratio
105.4 
Actual Ratio [Member] |
Ameren Illinois Company
 
Long-Term Debt And Equity Financings [Line Items]
 
Restricted payment interest coverage ratio, Actual
6.9 
Dividend Coverage Ratio
2.8 
Other Income and Expenses (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Other Nonoperating Income (Expense) [Line Items]
 
 
 
 
Allowance for equity funds used during construction
$ 5 1
$ 6 1
$ 13 1
$ 11 1
Interest income on industrial development revenue bonds
6 1
6 1
13 1
13 1
Interest and dividend income
4 1
4 1
8 1
8 1
Other
1 1
0 1
2 1
3 1
Total miscellaneous income
16 1
16 1
36 1
35 1
Donations
2 1
2 1
7 1
10 1
Other
4 1
4 1
6 1
7 1
Total miscellaneous expense
6 1
6 1
13 1
17 1
Union Electric Company
 
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
 
Allowance for equity funds used during construction
3 
5 
10 
9 
Interest income on industrial development revenue bonds
6 
6 
13 
13 
Interest and dividend income
0 
1 
0 
1 
Other
0 
0 
1 
0 
Total miscellaneous income
9 
12 
24 
23 
Donations
1 
1 
2 
3 
Other
1 
1 
2 
2 
Total miscellaneous expense
2 
2 
4 
5 
Ameren Illinois Company
 
 
 
 
Other Nonoperating Income (Expense) [Line Items]
 
 
 
 
Allowance for equity funds used during construction
2 
1 
3 
2 
Interest and dividend income
3 
3 
7 
7 
Other
1 
0 
1 
2 
Total miscellaneous income
6 
4 
11 
11 
Donations
1 
1 
5 
4 
Other
2 
1 
3 
3 
Total miscellaneous expense
$ 3 
$ 2 
$ 8 
$ 7 
Derivative Financial Instruments (Open Gross Derivative Volumes By Commodity Type) (Detail)
Jun. 30, 2016
gal
Dec. 31, 2015
gal
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
24,000,000 1
35,000,000 1
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
161,000,000 
181,000,000 
Power
 
 
Derivative [Line Items]
 
 
Quantity
11,000,000 
11,000,000 
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
395,000 
494,000 
Union Electric Company |
Fuel Oils
 
 
Derivative [Line Items]
 
 
Quantity
24,000,000 1
35,000,000 1
Union Electric Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
30,000,000 
30,000,000 
Union Electric Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
1,000,000 
1,000,000 
Union Electric Company |
Uranium
 
 
Derivative [Line Items]
 
 
Quantity
395,000 
494,000 
Ameren Illinois Company |
Natural Gas
 
 
Derivative [Line Items]
 
 
Quantity
131,000,000 
151,000,000 
Ameren Illinois Company |
Power
 
 
Derivative [Line Items]
 
 
Quantity
10,000,000 
10,000,000 
Derivative Financial Instruments (Derivative Instruments Carrying Value) (Detail) (Not Designated As Hedging Instrument, USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Derivative [Line Items]
 
 
Derivative assets
$ 21 1
$ 18 1
Derivative liabilities
214 2
264 2
Fuel Oils |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
12 
22 
Fuel Oils |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 
7 
Natural Gas |
Other Current Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 
1 
Natural Gas |
Other Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
4 
1 
Natural Gas |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
14 
38 
Natural Gas |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
12 
26 
Power |
Other Current Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
15 
16 
Power |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
13 
13 
Power |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
157 
157 
Uranium |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 
1 
Uranium |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
3 
 
Union Electric Company
 
 
Derivative [Line Items]
 
 
Derivative assets
16 1
17 1
Derivative liabilities
28 2
44 2
Union Electric Company |
Fuel Oils |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
12 
22 
Union Electric Company |
Fuel Oils |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
2 
7 
Union Electric Company |
Natural Gas |
Other Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
1 
1 
Union Electric Company |
Natural Gas |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
3 
6 
Union Electric Company |
Natural Gas |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 
8 
Union Electric Company |
Power |
Other Current Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
15 
16 
Union Electric Company |
Power |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 
 
Union Electric Company |
Power |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Union Electric Company |
Uranium |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
1 
1 
Union Electric Company |
Uranium |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
3 
 
Ameren Illinois Company
 
 
Derivative [Line Items]
 
 
Derivative assets
5 1
1 1
Derivative liabilities
186 2
220 2
Ameren Illinois Company |
Fuel Oils |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Ameren Illinois Company |
Fuel Oils |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Ameren Illinois Company |
Natural Gas |
Other Current Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
2 
1 
Ameren Illinois Company |
Natural Gas |
Other Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
3 
 
Ameren Illinois Company |
Natural Gas |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Ameren Illinois Company |
Natural Gas |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
6 
18 
Ameren Illinois Company |
Natural Gas |
Mark To Market Derivative Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
11 
32 
Ameren Illinois Company |
Power |
Other Current Assets
 
 
Derivative [Line Items]
 
 
Derivative assets
0 
0 
Ameren Illinois Company |
Power |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Ameren Illinois Company |
Power |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
157 
157 
Ameren Illinois Company |
Power |
Mark To Market Derivative Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
12 
13 
Ameren Illinois Company |
Uranium |
Other Current Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
0 
0 
Ameren Illinois Company |
Uranium |
Other Deferred Credits And Liabilities
 
 
Derivative [Line Items]
 
 
Derivative liabilities
$ 0 
 
Derivative Financial Instruments (Offsetting Derivative Assets and Liabilities) (Details) (Commodity Contract, USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
$ 21 1
$ 18 1
Derivative Instruments
6 
1 
Derivative, Collateral, Obligation to Return Cash
0 2
0 2
Net Amount
15 
17 
Gross Amounts Recognized in the Balance Sheet
214 1
264 1
Derivative Instruments
6 
1 
Cash Collateral Received/Posted
4 2
11 2
Net Amount
204 
252 
Union Electric Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
16 1
17 1
Derivative Instruments
2 
1 
Derivative, Collateral, Obligation to Return Cash
0 2
0 2
Net Amount
14 
16 
Gross Amounts Recognized in the Balance Sheet
28 1
44 1
Derivative Instruments
2 
1 
Cash Collateral Received/Posted
4 2
8 2
Net Amount
22 
35 
Ameren Illinois Company
 
 
Offsetting Assets and Liabilities [Line Items]
 
 
Gross Amounts Recognized in the Balance Sheet
5 
1 
Derivative Instruments
4 
0 
Derivative, Collateral, Obligation to Return Cash
0 2
0 2
Net Amount
1 
1 
Gross Amounts Recognized in the Balance Sheet
186 1
220 1
Derivative Instruments
4 
0 
Cash Collateral Received/Posted
0 2
3 2
Net Amount
$ 182 
$ 217 
Fair Value Measurements (Schedule Of Valuation Process And Unobservable Inputs) (Detail) (USD $)
In Millions, unless otherwise specified
6 Months Ended 12 Months Ended
Jun. 30, 2016
Dec. 31, 2015
Natural Gas |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.22% 1 2
0.40% 1 2
Nodal basis
(0.80)3
(0.10)3
Credit risk
0.38% 1 2
0.40% 1 2
Natural Gas |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
6.00% 1 2
12.00% 1 2
Nodal basis
0 3
0 3
Credit risk
0.38% 1 2
0.40% 1 2
Natural Gas |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
2.00% 1 2
7.00% 1 2
Nodal basis
(0.50)3
(0.10)3
Credit risk
0.38% 1 2
0.40% 1 2
Natural Gas |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
 
35.00% 3
Nodal basis
 
(0.30)1
Natural Gas |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
 
55.00% 3
Nodal basis
 
0 1
Natural Gas |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
 
45.00% 3
Nodal basis
 
(0.20)1
Natural Gas |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
$ 0 4
$ 1 4
Natural Gas |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(1)4
(1)4
Power |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.56% 1 2
0.86% 1 2
Nodal basis
(9)5
(10)5
Credit risk
0.38% 1 2
0.40% 1 2
Average forward peak and off-peak pricing
27 5
22 5
Estimated auction price
(309)3
(270)3
Power |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.56% 1 2
0.86% 1 2
Nodal basis
(1)5
(1)5
Credit risk
0.38% 1 2
0.40% 1 2
Average forward peak and off-peak pricing
43 5
39 5
Estimated auction price
1,509 3
2,057 3
Power |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Counterparty credit risk
0.56% 1 2
0.86% 1 2
Nodal basis
(2)5
(3)5
Credit risk
0.38% 1 2
0.40% 1 2
Average forward peak and off-peak pricing
30 5
29 5
Estimated auction price
96 3
211 3
Power |
Fundamental Energy Production Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 3 6
3.00% 3 6
Estimated future gas prices
3 3
3 3
Power |
Fundamental Energy Production Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 3 6
3.00% 3 6
Estimated future gas prices
5 3
4 3
Power |
Fundamental Energy Production Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Escalation rate
4.00% 3 6
3.00% 3 6
Estimated future gas prices
4 3
4 3
Power |
Contract Price Allocation |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
5 3
5 3
Power |
Contract Price Allocation |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
7 3
7 3
Power |
Contract Price Allocation |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Estimated renewable energy credit costs
6 3
6 3
Power |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
15 4 7
16 4 7
Power |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
(170)4 7
(170)4 7
Uranium |
Discounted Cash Flow |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.38% 1 2
0.40% 1 2
Average forward pricing
27 3
35 3
Uranium |
Discounted Cash Flow |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.38% 1 2
0.40% 1 2
Average forward pricing
30 3
42 3
Uranium |
Discounted Cash Flow |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Credit risk
0.38% 1 2
0.40% 1 2
Average forward pricing
29 3
37 3
Uranium |
Option Model |
Minimum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
21.00% 3
20.00% 3
Uranium |
Option Model |
Maximum
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
21.00% 3
20.00% 3
Uranium |
Option Model |
Weighted Average
 
 
Fair Value Inputs [Abstract]
 
 
Volatilities
21.00% 3
20.00% 3
Uranium |
Derivative Assets
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative assets
0 4
0 4
Uranium |
Derivative Liabilities
 
 
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
 
 
Derivative liabilities
$ (4)4
$ (1)4
Fair Value Measurements (Schedule Of Fair Value Hierarchy Of Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
$ 580 1
$ 557 2
Assets fair value
601 3
575 3
Excluded receivables, payables, and accrued income, net
2 
(1)
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
580 1
557 2
Assets fair value
596 3
574 3
Excluded receivables, payables, and accrued income, net
2 
(1)
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
21 3
18 3
Derivative liabilities
214 3
264 3
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
16 3
17 3
Derivative liabilities
28 3
44 3
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 
1 
Derivative liabilities
186 3
220 3
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
4 
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
4 
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
378 
364 
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
378 
364 
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
56 
58 
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
56 
58 
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
129 
109 
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
129 
109 
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
16 
22 
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
16 
22 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
379 
368 
Assets fair value
380 3
368 3
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
379 
368 
Assets fair value
379 3
368 3
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
0 3
Derivative liabilities
14 3
30 3
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
14 3
29 3
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
1 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
4 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
1 
4 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
378 
364 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
378 
364 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Observable Inputs (Level 2)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
201 
189 
Assets fair value
206 3
190 3
Significant Other Observable Inputs (Level 2) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
201 
189 
Assets fair value
202 3
189 3
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 3
1 3
Derivative liabilities
25 3
62 3
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
0 3
Derivative liabilities
9 3
13 3
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
16 3
49 3
Significant Other Observable Inputs (Level 2) |
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Observable Inputs (Level 2) |
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Observable Inputs (Level 2) |
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Observable Inputs (Level 2) |
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
56 
58 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
56 
58 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
129 
109 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
129 
109 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
16 
22 
Significant Other Observable Inputs (Level 2) |
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
16 
22 
Significant Other Unobservable Inputs (Level 3)
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Assets fair value
15 3
17 3
Significant Other Unobservable Inputs (Level 3) |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Assets fair value
15 3
17 3
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
17 3
Derivative liabilities
175 3
172 3
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
17 3
Derivative liabilities
5 3
2 3
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
170 3
170 3
Significant Other Unobservable Inputs (Level 3) |
Cash and cash equivalents
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Cash and cash equivalents |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Equity Securities |
U.S. large capitalization
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Equity Securities |
U.S. large capitalization |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
Corporate bonds
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
Corporate bonds |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
US treasury and government securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
US treasury and government securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
Other Debt Securities
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Significant Other Unobservable Inputs (Level 3) |
Debt Securities |
Other Debt Securities |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Nuclear Decommissioning Trust Fund
0 
0 
Uranium |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
4 3
1 3
Uranium |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
4 3
1 3
Uranium |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Uranium |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Uranium |
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Uranium |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Uranium |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
4 3
1 3
Uranium |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
4 3
1 3
Fuel Oils |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
14 3
29 3
Fuel Oils |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
14 3
29 3
Fuel Oils |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
14 3
29 3
Fuel Oils |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
14 3
29 3
Fuel Oils |
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Fuel Oils |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Fuel Oils |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Fuel Oils |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Power |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
16 3
Derivative liabilities
170 3
170 3
Power |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
16 3
Derivative liabilities
1 3
 
Power |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
169 3
170 3
Power |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
0 3
0 3
Power |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
0 3
 
Power |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 3
Power |
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
0 3
0 3
Power |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
0 3
 
Power |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
0 3
0 
Power |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
16 3
Derivative liabilities
170 3
170 3
Power |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
15 3
16 3
Derivative liabilities
1 3
 
Power |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative liabilities
169 3
170 3
Natural Gas |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
6 3
2 3
Derivative liabilities
26 3
64 3
Natural Gas |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
1 3
Derivative liabilities
9 3
14 3
Natural Gas |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 3
1 3
Derivative liabilities
17 3
50 3
Natural Gas |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
0 3
Derivative liabilities
0 3
1 3
Natural Gas |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
0 3
0 3
Natural Gas |
Quoted Prices In Active Markets For Identical Assets or Liabilities (Level 1) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
0 3
Derivative liabilities
0 3
1 3
Natural Gas |
Significant Other Observable Inputs (Level 2) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
5 3
1 3
Derivative liabilities
25 3
62 3
Natural Gas |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
1 3
0 3
Derivative liabilities
9 3
13 3
Natural Gas |
Significant Other Observable Inputs (Level 2) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
4 3
1 3
Derivative liabilities
16 3
49 3
Natural Gas |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
1 3
Derivative liabilities
1 3
1 3
Natural Gas |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
1 3
Derivative liabilities
0 3
1 3
Natural Gas |
Significant Other Unobservable Inputs (Level 3) |
Commodity Contract |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Derivative assets
0 3
0 3
Derivative liabilities
$ 1 3
$ 0 3
Fair Value Measurements (Schedule Of Changes In The Fair Value Of Financial Assets And Liabilities Classified As Level Three In The Fair Value Hierarchy) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended 3 Months Ended 6 Months Ended
Jun. 30, 2015
Fuel Oils
Jun. 30, 2015
Fuel Oils
Jun. 30, 2016
Uranium
Jun. 30, 2015
Uranium
Jun. 30, 2016
Uranium
Dec. 31, 2014
Uranium
Jun. 30, 2016
Natural Gas
Jun. 30, 2015
Natural Gas
Jun. 30, 2016
Natural Gas
Jun. 30, 2015
Natural Gas
Jun. 30, 2016
Power
Jun. 30, 2015
Power
Jun. 30, 2016
Power
Jun. 30, 2015
Power
Jun. 30, 2015
Union Electric Company
Fuel Oils
Jun. 30, 2015
Union Electric Company
Fuel Oils
Jun. 30, 2016
Union Electric Company
Uranium
Jun. 30, 2015
Union Electric Company
Uranium
Jun. 30, 2016
Union Electric Company
Uranium
Dec. 31, 2014
Union Electric Company
Uranium
Jun. 30, 2016
Union Electric Company
Natural Gas
Jun. 30, 2015
Union Electric Company
Natural Gas
Jun. 30, 2016
Union Electric Company
Natural Gas
Jun. 30, 2015
Union Electric Company
Natural Gas
Jun. 30, 2016
Union Electric Company
Power
Jun. 30, 2015
Union Electric Company
Power
Jun. 30, 2016
Union Electric Company
Power
Jun. 30, 2015
Union Electric Company
Power
Jun. 30, 2016
Ameren Illinois Company
Natural Gas
Jun. 30, 2015
Ameren Illinois Company
Natural Gas
Jun. 30, 2016
Ameren Illinois Company
Natural Gas
Jun. 30, 2015
Ameren Illinois Company
Natural Gas
Jun. 30, 2016
Ameren Illinois Company
Power
Jun. 30, 2015
Ameren Illinois Company
Power
Jun. 30, 2016
Ameren Illinois Company
Power
Jun. 30, 2015
Ameren Illinois Company
Power
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3
$ 2 
$ 2 
 
 
 
 
 
 
 
 
 
 
 
 
$ 2 
$ 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Beginning balance
(6)
(6)
(4)
(1)
(1)
(2)
(1)
0 
0 
(1)
(181)
(160)
(154)
(133)
(6)
(6)
(4)
(1)
(1)
(2)
0 
(1)
0 
(1)
6 
4 
16 
9 
(1)
1 
0 
0 
(187)
(164)
(170)
(142)
Included in regulatory assets/liabilities
1 
 
 
(1)
(3)
 
(1)
 
(1)
 
13 
(4)
(11)
(31)
1 
 
 
(1)
(3)
 
0 
 
0 
 
(1)
 
(4)
(2)
(1)
 
(1)
 
14 
(4)
(7)
(29)
Purchases
 
 
 
 
 
 
 
(1)
 
 
13 
29 
13 
29 
 
 
 
 
 
 
 
0 
 
 
13 
29 
13 
29 
 
(1)
 
 
0 
0 
0 
0 
Settlements
2 
3 
 
 
 
 
1 
 
 
 
 
(3)
(3)
(3)
2 
3 
 
 
 
 
0 
1 
 
1 
(4)
(6)
(11)
(9)
1 
(1)
 
(1)
4 
3 
8 
6 
Ending balance
(1)
(1)
(4)
(2)
(4)
(2)
(1)
(1)
(1)
(1)
(155)
(138)
(155)
(138)
(1)
(1)
(4)
(2)
(4)
(2)
0 
0 
0 
0 
14 
27 
14 
27 
(1)
(1)
(1)
(1)
(169)
(165)
(169)
(165)
Change in unrealized gains (losses) related to assets/liabilities held at period end
$ 3 
 
$ 0 
$ (1)
$ (3)
 
$ (1)
$ 0 
$ (1)
$ 0 
$ 14 
$ (4)
$ (5)
$ (29)
$ 3 
 
$ 0 
$ (1)
$ (3)
 
$ 0 
$ 0 
$ 0 
$ 0 
$ 0 
$ 1 
$ 0 
$ 0 
$ (1)
$ 0 
$ (1)
$ 0 
$ 14 
$ (5)
$ (5)
$ (29)
Fair Value Measurements (Schedule Of Carrying Amounts And Estimated Fair Values Of Long-Term Debt And Preferred Stock) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Fair Value
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
$ 7,973 1
$ 7,814 1
Preferred stock
127 1
125 1
Fair Value |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
4,539 
4,449 
Preferred stock
77 
75 
Fair Value |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
2,692 
2,665 
Preferred stock
50 
50 
Carrying Amount
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
7,036 1
7,275 1
Preferred stock
142 1
142 1
Carrying Amount |
Union Electric Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
3,999 
4,110 
Preferred stock
80 
80 
Carrying Amount |
Ameren Illinois Company
 
 
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
 
 
Long-term debt (including current portion)
2,343 
2,471 
Preferred stock
$ 62 
$ 62 
Related Party Transactions Narrative (Details) (April 2016 Procurement [Member], Ameren Illinois Company, Ameren Illinois Power Supply Agreements with Ameren Missouri)
6 Months Ended
Jun. 30, 2016
MWh
April 2016 Procurement [Member] |
Ameren Illinois Company |
Ameren Illinois Power Supply Agreements with Ameren Missouri
 
Related Party Transaction [Line Items]
 
Long-term Contract for Purchase of Electric Power, Related Party Contract, Fixed Power
375,200 
Long-term Contract for Purchase of Electric Power, Related Party Contract, Fixed Power, Rate
34.71 
Commitments And Contingencies (Callaway Energy Center) (Detail) (USD $)
6 Months Ended
Jun. 30, 2016
Commitments And Contingencies [Line Items]
 
Threshold for which a retrospective assessment for a covered loss is necessary
$ 375,000,000 
Annual payment in the event of an incident at any licensed commercial reactor
19,000,000 
Aggregate maximum assessment per incident under Price-Anderson liability provisions of Atomic Energy Act
127,000,000 
Maximum annual payment in calendar year per reactor incident under Price Andersen Liability Provisions of Atomic Energy Act
19,000,000 
Amount of weekly indemnity coverage commencing eight weeks after power outage
4,500,000 
Number of weeks of coverage after the first eight weeks of an outage
1 year 
Amount of additional weekly indemnity coverage commencing after initial indemnity coverage
3,600,000 
Number of additional weeks after initial indemnity coverage for power outage, minimum
1 year 4 months 10 days 
Inflationary adjustment prescribed by most recent Price-Anderson Act renewal, in years
5 years 
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period
3,240,000,000 
Public Liability
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
13,361,000,000 1
Maximum Assessments for Single Incidents
127,000,000 
Public Liability And Nuclear Worker Liability - American Nuclear Insurers
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
375,000,000 
Maximum Assessments for Single Incidents
0 
Public Liability And Nuclear Worker Liability - Pool Participation
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
12,986,000,000 2
Maximum Assessments for Single Incidents
127,000,000 3
Property Damage
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
3,200,000,000 
Maximum Assessments for Single Incidents
30,000,000 
Property Damage - Nuclear Electric Insurance Ltd
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
2,750,000,000 4
Maximum Assessments for Single Incidents
30,000,000 5
Property Damage European Mutual Association for Nuclear Insurance
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
450,000,000 6
Replacement Power - Nuclear Electric Insurance Ltd
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
490,000,000 7
Maximum Assessments for Single Incidents
7,000,000 5
Amount of weekly indemnity coverage thereafter not exceeding policy limit
490,000,000 
Sub-limit of for non-nuclear events
328,000,000 
Non-radiation event
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
2,300,000,000 
Aggregate nuclear power industry insurance policy limit for losses from terrorist attacks within twelve month period
1,830,000,000 
Radiation Event
 
Commitments And Contingencies [Line Items]
 
Maximum Coverages
$ 2,750,000,000 
Commitments And Contingencies (Other Obligations) (Detail) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2016
MWh
Long-term Purchase Commitment [Line Items]
 
Total Other Obligations
$ 4,465 
Union Electric Company
 
Long-term Purchase Commitment [Line Items]
 
Total Other Obligations
2,614 
Ameren Illinois Company
 
Long-term Purchase Commitment [Line Items]
 
Total Other Obligations
1,790 
April 2016 Procurement [Member] |
Ameren Illinois Company
 
Long-term Purchase Commitment [Line Items]
 
Amount of Megawatthours
3,609,800 
Long-term Purchase Commitment, Amount
$ 105 
Commitments And Contingencies (Environmental Matters) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Minimum
 
Loss Contingencies [Line Items]
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
$ 600 
Maximum
 
Loss Contingencies [Line Items]
 
Estimated capital costs to comply with existing and known federal and state air emissions regulations
700 
Union Electric Company
 
Loss Contingencies [Line Items]
 
Number of Energy Center Scrubbers
2 
Manufactured Gas Plant
 
Loss Contingencies [Line Items]
 
Accrual for environmental loss contingencies
217.0 
Manufactured Gas Plant |
Ameren Illinois Company
 
Loss Contingencies [Line Items]
 
Number of remediation sites
44 
Accrual for environmental loss contingencies
217.0 
Manufactured Gas Plant |
Ameren Illinois Company |
Minimum
 
Loss Contingencies [Line Items]
 
Estimate of possible loss
217.0 
Manufactured Gas Plant |
Ameren Illinois Company |
Maximum
 
Loss Contingencies [Line Items]
 
Estimate of possible loss
306.0 
Other Environmental |
Ameren Illinois Company
 
Loss Contingencies [Line Items]
 
Accrual for environmental loss contingencies
0.7 
Sauget Area Two |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Accrual for environmental loss contingencies
1.0 
Sauget Area Two |
Union Electric Company |
Minimum
 
Loss Contingencies [Line Items]
 
Estimate of possible loss
1.0 
Sauget Area Two |
Union Electric Company |
Maximum
 
Loss Contingencies [Line Items]
 
Estimate of possible loss
2.5 
Substation in St Charles, Missouri |
Union Electric Company
 
Loss Contingencies [Line Items]
 
Accrual for environmental loss contingencies
$ 0.6 
Callaway Energy Center (Narrative) (Detail) (Nuclear Plant, USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2016
mill
Nuclear Plant
 
Nuclear Waste Matters [Line Items]
 
Number of mills charged for NWF fee
1 
Annual decommissioning costs included in costs of service
$ 7 
Retirement Benefits (Components Of Net Periodic Benefit Cost) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Pension Plan
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Service cost
$ 20 
$ 22 
$ 40 
$ 46 
Interest cost
45 
43 
92 
87 
Expected return on plan assets
(63)
(62)
(126)
(124)
Prior service cost (benefit)
0 
0 
0 
0 
Actuarial loss
7 
19 
16 
37 
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements
0 
1 
0 
1 
Net periodic benefit cost
9 1 2
23 1 2
22 1 2
47 1 2
Other Postretirement Benefit Plan, Defined Benefit
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Service cost
5 
6 
10 
11 
Interest cost
12 
12 
24 
24 
Expected return on plan assets
(18)
(17)
(36)
(34)
Prior service cost (benefit)
(1)
(1)
(2)
(2)
Actuarial loss
(2)
2 
(5)
3 
Defined Benefit Plan, Recognized Net Gain (Loss) Due to Settlements
0 
0 
0 
0 
Net periodic benefit cost
(4)1 2
2 1 2
(9)1 2
2 1 2
Union Electric Company |
Pension Plan
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
5 
13 
13 
28 
Union Electric Company |
Other Postretirement Benefit Plan, Defined Benefit
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
(1)
3 
(2)
4 
Ameren Illinois Company |
Pension Plan
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
6 
10 
11 
19 
Ameren Illinois Company |
Other Postretirement Benefit Plan, Defined Benefit
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
(3)
(1)
(7)
(2)
Other Affiliated Entities and Intercompany Eliminations [Member] |
Pension Plan
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
(2)
0 
(2)
0 
Other Affiliated Entities and Intercompany Eliminations [Member] |
Other Postretirement Benefit Plan, Defined Benefit
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Net periodic benefit cost
$ 0 
$ 0 
$ 0 
$ 0 
Retirement Benefits (Summary Of Benefit Plan Costs Incurred) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Pension Plan
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
$ 9 1 2
$ 23 1 2
$ 22 1 2
$ 47 1 2
Pension Plan |
Union Electric Company
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
5 
13 
13 
28 
Pension Plan |
Ameren Illinois Company
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
6 
10 
11 
19 
Pension Plan |
Other Affiliated Entities and Intercompany Eliminations [Member]
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
(2)
0 
(2)
0 
Other Postretirement Benefit Plan, Defined Benefit
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
(4)1 2
2 1 2
(9)1 2
2 1 2
Other Postretirement Benefit Plan, Defined Benefit |
Union Electric Company
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
(1)
3 
(2)
4 
Other Postretirement Benefit Plan, Defined Benefit |
Ameren Illinois Company
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
(3)
(1)
(7)
(2)
Other Postretirement Benefit Plan, Defined Benefit |
Other Affiliated Entities and Intercompany Eliminations [Member]
 
 
 
 
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
 
 
 
 
Defined Benefit Plan, Net Periodic Benefit Cost
$ 0 
$ 0 
$ 0 
$ 0 
Divestiture Transactions and Discontinued Operations Divestiture Transactions and Discontinued operations (Components of Discontinued Operations in Consolidated Statement of Income (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Discontinued Operations and Disposal Groups [Abstract]
 
 
 
 
Operating revenues
$ 0 
$ 0 
$ 0 
$ 0 
Operating benefits (expenses)
0 
0 
0 
3 
Operating income before income tax
0 
0 
0 
3 
Income tax benefit
0 
52 
0 
49 
Income from Discontinued Operations, Net of Taxes
$ 0 
$ 52 
$ 0 
$ 52 
Divestiture Transactions and Discontinued Operations Divestiture Transactions and DIscontinued Operations (Components of Assets and Liabilities on Consolidated Balance Sheet) (Details) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2016
Dec. 31, 2015
Assets of discontinued operations
 
 
Accumulated deferred income taxes, net
$ 14 
$ 14 
Total assets of discontinued operations
14 
14 
Liabilities of discontinued operations
 
 
Accounts payable and other current obligations
1 
1 
Asset retirement obligations
26 1
28 1
Total liabilities of discontinued operations
$ 27 
$ 29 
Segment Information (Schedule Of Segment Reporting Information By Segment) (Detail) (USD $)
In Millions, unless otherwise specified
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
segment
Jun. 30, 2015
Dec. 31, 2015
Segment Reporting Information [Line Items]
 
 
 
 
 
Number of Reportable Segments
 
 
2 
 
 
External revenues
$ 1,427 
$ 1,401 
$ 2,861 
$ 2,957 
 
Net income (loss) attributable to Ameren Common Shareholders from continuing operations
147 
98 
252 
206 
 
Total assets
23,793 
 
23,793 
 
23,640 
Assets of discontinued operations
14 
 
14 
 
14 
Union Electric Company
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
Number of Reportable Segments
 
 
1 
 
 
External revenues
857 
872 
1,583 
1,665 
 
Intersegment revenues
10 
12 
25 
19 
 
Net income (loss) attributable to Ameren Common Shareholders from continuing operations
92 
61 
106 
102 
 
Total assets
13,649 
 
13,649 
 
13,851 
Ameren Illinois Company
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
Number of Reportable Segments
 
 
1 
 
 
External revenues
541 
512 
1,217 
1,256 
 
Intersegment revenues
1 
1 
2 
2 
 
Net income (loss) attributable to Ameren Common Shareholders from continuing operations
45 
31 
104 
84 
 
Total assets
8,999 
 
8,999 
 
8,903 
Other
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
External revenues
29 
17 
61 
36 
 
Intersegment revenues
1 
0 
1 
1 
 
Net income (loss) attributable to Ameren Common Shareholders from continuing operations
10 
6 
42 
20 
 
Total assets
1,276 
 
1,276 
 
1,139 
Intersegment Eliminations
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
Intersegment revenues
(12)
(13)
(28)
(22)
 
Total assets
(145)
 
(145)
 
(267)
Consolidated, Continuing Operations
 
 
 
 
 
Segment Reporting Information [Line Items]
 
 
 
 
 
External revenues
1,427 
1,401 
2,861 
2,957 
 
Net income (loss) attributable to Ameren Common Shareholders from continuing operations
147 
98 
252 
206 
 
Total assets
$ 23,779 1
 
$ 23,779 1
 
$ 23,626 1