Cover Page - shares	6 Months Ended
Cover Page - shares	Jun. 30, 2020	Jul. 31, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-34501
Entity Registrant Name	JUNIPER NETWORKS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0422528
Entity Address, Address Line One	1133 Innovation Way
Entity Address, City or Town	Sunnyvale,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94089
City Area Code	408
Local Phone Number	745-2000
Title of 12(b) Security	Common Stock, par value $0.00001 per share
Trading Symbol	JNPR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		331,750,363
Entity Central Index Key	0001043604
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total net revenues	$ 1,086.3	$ 1,102.5	$ 2,084.3	$ 2,104.2
Cost of revenues:
Total cost of revenues	466.7	465.7	885.4	885.1
Gross margin	619.6	636.8	1,198.9	1,219.1
Operating expenses:
Research and development	241.0	244.0	473.5	471.6
Sales and marketing	224.2	229.0	463.4	457.5
General and administrative	59.1	60.0	118.4	128.2
Restructuring charges	4.8	21.4	13.7	36.7
Total operating expenses	529.1	554.4	1,069.0	1,094.0
Operating income	90.5	82.4	129.9	125.1
Other expense, net	(4.4)	(4.6)	(15.5)	(2.8)
Income before income taxes	86.1	77.8	114.4	122.3
Income tax provision	24.9	31.6	32.8	45.0
Net income	$ 61.2	$ 46.2	$ 81.6	$ 77.3
Net income per share:
Basic (in dollars per share)	$ 0.18	$ 0.13	$ 0.25	$ 0.22
Diluted, (in dollars per share)	$ 0.18	$ 0.13	$ 0.24	$ 0.22
Weighted-average shares used to compute net income per share:
Basic (in shares)	331.0	346.3	330.9	347.2
Diluted (in shares)	333.1	349.1	334.7	351.7
Product
Total net revenues	$ 692.3	$ 713.9	$ 1,301.1	$ 1,332.6
Cost of revenues:
Total cost of revenues	321.7	314.3	590.7	584.3
Service
Total net revenues	394.0	388.6	783.2	771.6
Cost of revenues:
Total cost of revenues	$ 145.0	$ 151.4	$ 294.7	$ 300.8

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 61.2	$ 46.2	$ 81.6	$ 77.3
Available-for-sale debt securities:
Change in net unrealized gains, net of tax provision of ($2.7) and ($1.9) during the three and six months ended June 30, 2020, respectively, and tax provision of ($0.2) and ($0.8) for the comparable periods in 2019, respectively	8.7	2.0	5.7	3.8
Net realized gains and losses reclassified into net income, net of tax	(0.2)	0.0	0.3	0.0
Net change on available-for-sale debt securities, net of tax	8.5	2.0	6.0	3.8
Cash flow hedges:
Change in net unrealized gains and (losses), net of tax benefit (provision) of ($1.8) and $2.4 during the three and six months ended June 30, 2020, respectively, and tax benefit (provision) of $0.2 and ($1.1) for the comparable periods in 2019, respectively	16.1	(1.8)	(8.8)	0.3
Net realized losses reclassified into net income, net of tax benefit of $0.8 and $0.9 during the three and six months ended June 30, 2020, respectively, and tax provision of ($0.6) and ($0.8) for the comparable periods in 2019, respectively	6.1	0.3	7.5	1.5
Net change on cash flow hedges, net of tax	22.2	(1.5)	(1.3)	1.8
Change in foreign currency translation adjustments	5.6	(0.9)	(9.1)	1.3
Other comprehensive income (loss), net of tax	36.3	(0.4)	(4.4)	6.9
Comprehensive income	$ 97.5	$ 45.8	$ 77.2	$ 84.2

Condensed Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on available-for-sale securities, tax benefit (provision)	$ (2.7)	$ (0.2)	$ (1.9)	$ (0.8)
Unrealized (loss) gain on cash flow hedges, tax benefit (provision)	(1.8)	0.2	2.4	(1.1)
Reclassification adjustment for realized net loss (gain) on cash flow hedges included in net income, tax benefit (provision)	$ 0.8	$ (0.6)	$ 0.9	$ (0.8)

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 1,460.3	$ 1,215.8
Short-term investments	397.6	738.0
Accounts receivable, net of allowances	754.7	879.7
Prepaid expenses and other current assets	388.6	376.3
Total current assets	3,001.2	3,209.8
Property and equipment, net	781.6	830.9
Operating lease assets	174.2	169.7
Long-term investments	712.4	589.8
Purchased intangible assets, net	161.3	185.8
Goodwill	3,337.1	3,337.1
Other long-term assets	573.7	514.6
Total assets	8,741.5	8,837.7
Current liabilities:
Accounts payable	238.0	219.5
Accrued compensation	215.7	229.0
Deferred revenue	834.5	812.9
Other accrued liabilities	308.1	282.5
Total current liabilities	1,596.3	1,543.9
Long-term debt	1,720.1	1,683.9
Long-term deferred revenue	377.1	410.5
Long-term income taxes payable	360.3	372.6
Long-term operating lease liabilities	162.1	158.1
Other long-term liabilities	61.3	58.1
Total liabilities	4,277.2	4,227.1
Commitments and contingencies (Note 13)
Stockholders' equity:
Convertible preferred stock, $0.00001 par value; 10.0 shares authorized; none issued and outstanding	0.0	0.0
Common stock, $0.00001 par value; 1,000.0 shares authorized; 331.7 shares and 335.9 shares issued and outstanding as of June 30, 2020 and December 31, 2019, respectively	0.0	0.0
Additional paid-in capital	7,255.7	7,370.5
Accumulated other comprehensive loss	(22.9)	(18.5)
Accumulated deficit	(2,768.5)	(2,741.4)
Total stockholders' equity	4,464.3	4,610.6
Total liabilities and stockholders' equity	$ 8,741.5	$ 8,837.7

Condensed Consolidated Balance Sheets (Parentheticals) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Convertible preferred stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Convertible preferred stock - shares authorized (shares)	10,000,000	10,000,000
Convertible preferred stock - issued (shares)	0	0
Convertible preferred stock - outstanding (shares)	0	0
Common stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock - shares authorized (shares)	1,000,000,000	1,000,000,000
Common stock - issued (shares)	331,700,000	335,900,000
Common stock - outstanding (shares)	331,700,000	335,900,000

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net income	$ 81.6	$ 77.3
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	86.0	89.6
Depreciation, amortization, and accretion	106.0	101.7
Operating lease assets expense	21.0	21.3
Other	3.8	0.4
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	124.7	102.3
Prepaid expenses and other assets	(38.7)	(55.2)
Accounts payable	20.6	(28.1)
Accrued compensation	(11.7)	(15.8)
Income taxes payable	0.9	(3.8)
Other accrued liabilities	(14.2)	(20.1)
Deferred revenue	(10.2)	(21.4)
Net cash provided by operating activities	369.8	248.2
Cash flows from investing activities:
Purchases of property and equipment	(43.8)	(55.2)
Purchases of available-for-sale debt securities	(546.2)	(1,760.0)
Proceeds from sales of available-for-sale debt securities	156.9	628.5
Proceeds from maturities and redemptions of available-for-sale debt securities	622.7	906.0
Purchases of equity securities	(3.6)	(9.4)
Proceeds from sales of equity securities	3.7	4.1
Payments for business acquisitions, net of cash and cash equivalents acquired	0.0	(270.9)
Subsequent payments related to acquisitions in prior years	(0.2)	0.0
Net cash provided by (used in) investing activities	189.5	(556.9)
Cash flows from financing activities:
Repurchase and retirement of common stock	(205.3)	(303.8)
Proceeds from issuance of common stock	27.6	29.7
Payment of dividends	(131.8)	(131.7)
Payment of debt	0.0	(350.0)
Customer financing arrangement	4.8	0.0
Net cash used in financing activities	(304.7)	(755.8)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	(9.9)	2.1
Net increase (decrease) in cash, cash equivalents, and restricted cash	244.7	(1,062.4)
Cash, cash equivalents, and restricted cash at beginning of period	1,276.5	2,505.8
Cash, cash equivalents, and restricted cash at end of period	$ 1,521.2	$ 1,443.4

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Common Stock and Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Accumulated Deficit
Balance (in shares) at Dec. 31, 2018		346.4
Balance at Dec. 31, 2018	$ 4,823.2		$ 7,672.8	$ (18.2)	$ (2,831.4)
Balance (Accounting Standards Update 2017-12) at Dec. 31, 2018						$ 0.1	$ 0.1
Balance (Accounting Standards Update 2016-02) at Dec. 31, 2018						$ (4.8)	$ (4.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	77.3				77.3
Other comprehensive income, net	6.9			6.9
Issuance of common stock (in shares)		6.8
Issuance of common stock	29.7		29.7
Common stock assumed upon business combination	4.7		4.7
Repurchase and retirement of common stock (in shares)		(8.7)
Repurchase and retirement of common stock	(243.8)		(113.9)		(129.9)
Purchase of forward contract under accelerated share repurchase program (ASR)	(60.0)		(60.0)
Share-based compensation expense	89.6		89.6
Payments of cash dividends	(131.7)		(131.7)
Balance (in shares) at Jun. 30, 2019		344.5
Balance at Jun. 30, 2019	4,591.2		7,491.2	(11.3)	(2,888.7)
Balance (in shares) at Mar. 31, 2019		352.0
Balance at Mar. 31, 2019	4,851.2		7,668.6	(10.9)	(2,806.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46.2				46.2
Other comprehensive income, net	(0.4)			(0.4)
Issuance of common stock (in shares)		1.1
Issuance of common stock	0.2		0.2
Common stock assumed upon business combination	4.7		4.7
Repurchase and retirement of common stock (in shares)		(8.6)
Repurchase and retirement of common stock	(240.9)		(112.5)		(128.4)
Purchase of forward contract under accelerated share repurchase program (ASR)	(60.0)		(60.0)
Share-based compensation expense	55.7		55.7
Payments of cash dividends	(65.5)		(65.5)
Balance (in shares) at Jun. 30, 2019		344.5
Balance at Jun. 30, 2019	4,591.2		7,491.2	(11.3)	(2,888.7)
Balance (in shares) at Dec. 31, 2019		335.9
Balance at Dec. 31, 2019	4,610.6		7,370.5	(18.5)	(2,741.4)
Balance (in shares) at Mar. 31, 2020		331.0
Balance at Mar. 31, 2020	4,390.7		7,281.3	(59.2)	(2,831.4)
Balance (in shares) at Dec. 31, 2019		335.9
Balance at Dec. 31, 2019	4,610.6		7,370.5	(18.5)	(2,741.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	81.6				81.6
Other comprehensive income, net	(4.4)			(4.4)
Issuance of common stock (in shares)		6.4
Issuance of common stock	27.6		27.6
Repurchase and retirement of common stock (in shares)		(10.6)
Repurchase and retirement of common stock	(245.3)		(136.6)		(108.7)
Purchase of forward contract under accelerated share repurchase program (ASR)	40.0		40.0
Share-based compensation expense	86.0		86.0
Payments of cash dividends	(131.8)		(131.8)
Balance (in shares) at Jun. 30, 2020		331.7
Balance at Jun. 30, 2020	4,464.3		7,255.7	(22.9)	(2,768.5)
Balance (in shares) at Mar. 31, 2020		331.0
Balance at Mar. 31, 2020	4,390.7		7,281.3	(59.2)	(2,831.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	61.2				61.2
Other comprehensive income, net	36.3			36.3
Issuance of common stock (in shares)		0.8
Issuance of common stock	0.5		0.5
Repurchase and retirement of common stock (in shares)		(0.1)
Repurchase and retirement of common stock	(2.1)		(3.8)		1.7
Share-based compensation expense	44.0		44.0
Payments of cash dividends	(66.3)		(66.3)
Balance (in shares) at Jun. 30, 2020		331.7
Balance at Jun. 30, 2020	$ 4,464.3		$ 7,255.7	$ (22.9)	$ (2,768.5)

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.20	$ 0.19	$ 0.40	$ 0.38

Basis of Presentation and Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 1. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The Condensed Consolidated Financial Statements of Juniper Networks, Inc. (the “Company” or “Juniper”) were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet as of December 31, 2019 has been derived from the audited Consolidated Financial Statements at that date. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020, or any future period. These Condensed Consolidated Financial Statements and accompanying notes should be read in conjunction with the audited Consolidated Financial Statements and accompanying notes in the Company's Annual Report on Form 10-K for the year ended December 31, 2019 (the "Form 10-K"). We have evaluated all subsequent events through the date these condensed consolidated financial statements were issued. The preparation of the financial statements and related disclosures in accordance with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates under different assumptions or conditions. Summary of Significant Accounting Policies Except for the change in certain policies upon adoption of the accounting standards and the policy for interest rate lock cash flow hedges described below, there have been no significant changes to the Company's significant accounting policies described in Note 2, Significant Accounting Policies, in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K. The Company records changes in fair value of interest rate locks in accumulated other comprehensive income (loss) in the consolidated balance sheets, in the period of change. When the forecasted transaction occurs, the Company will start to amortize the accumulated gain or losses included as a component of other comprehensive income (loss) related to the interest rate lock cash flow hedges to interest expense. In the event the underlying forecasted transaction does not occur, or it becomes probable that it will not occur, the gain or loss on the related cash flow hedge from accumulated other comprehensive income (loss) will be reclassified to other income and expense within income statement. Recently Adopted Accounting Standards Fair Value Measurement: On January 1, 2020, the Company adopted ASU No. 2018-13 (Topic 820) Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds, and modifies certain disclosure requirements for fair value measurements under ASC 820. The Company adopted the standard under the prospective approach for certain modified or new disclosure requirements, and all other amendments in the standard under the retrospective approach. See Note 3, Fair Value Measurements for required disclosures. Simplifying the Test for Goodwill Impairment: On January 1, 2020, the Company adopted ASU No. 2017-04 (Topic 350) Intangibles—Goodwill and Other: Simplifying the Test for Goodwill Impairment, which removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. Under the amended guidance, a goodwill impairment charge will be recognized for the amount by which the carrying value of a reporting unit exceeds its fair value, not to exceed the carrying amount of goodwill. The Company adopted the standard under the prospective approach. Upon adoption, the standard did not have a material impact on the Consolidated Financial Statements. Credit Losses on Financial Instruments: On January 1, 2020, the Company adopted ASU 2016-13 (Topic 326) Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments, as further clarified by the Financial Accounting Standards Board (the "FASB") through the issuance of additional related ASUs, which requires the measurement and recognition of current expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model, which requires the use of forward-looking information to calculate credit loss estimates. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes will result in earlier recognition of credit losses. The Company adopted the standard under the modified retrospective approach. Upon adoption, the standard did not have a material impact on the Consolidated Financial Statements. Recent Accounting Standards Not Yet Adopted Reference Rate Reform: In March 2020, the FASB issued ASU No. 2020-04 (Topic 848), Reference Rate Reform - Facilitation of the Effects of Reference Rate Reform on Financial Reporting, which provides temporary optional expedients and exceptions to the existing guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from the London Interbank Offered Rate (LIBOR) and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (SOFR). The standard was effective upon issuance and may generally be applied through December 31, 2022, to any new or amended contracts, hedging relationships, and other transactions that reference LIBOR. The Company is currently evaluating the impact of the transition and disclosure requirements of the standard on its Consolidated Financial Statements. Simplifying the Accounting for Income Taxes: In December 2019, the FASB issued ASU No. 2019-12 (Topic 740) Income Taxes — Simplifying the Accounting for Income Taxes, which enhances and simplifies various aspects related to accounting for income taxes. This ASU is to be applied on a prospective basis with the exception of certain amendments that are to be applied on either a retrospective or modified retrospective basis. The new standard is effective for interim and annual periods beginning after December 15, 2020, with early adoption permitted. The Company is currently evaluating the impact of adoption on its Consolidated Financial Statements.

Cash Equivalents and Investments

6 Months Ended

Jun. 30, 2020

Cash Equivalents and Investments [Abstract]

Cash Equivalents and Investments

Note 2. Cash Equivalents and Investments

Investments in Available-for-Sale Debt Securities

The following table summarizes the Company's unrealized gains and losses and fair value of investments designated as available-for-sale debt securities as of June 30, 2020 and December 31, 2019 (in millions):



	As of June 30, 2020									As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Fixed income securities:
Asset-backed securities	$	73.9	$	0.5	$	—		$	74.4	$	81.3	$	0.1	$	—		$	81.4
Certificates of deposit	34.6		—		—			34.6		38.6		—		—			38.6
Commercial paper	74.2		—		—			74.2		168.2		—		—			168.2
Corporate debt securities	588.8		6.5		(0.5		)	594.8		604.9		0.7		(0.1		)	605.5
Foreign government debt securities	8.0		—		—			8.0		11.4		—		—			11.4
Time deposits	169.9		—		—			169.9		226.3		—		—			226.3
U.S. government agency securities	51.6		0.2		—			51.8		89.0		—		—			89.0
U.S. government securities	402.9		2.1		—			405.0		394.3		0.3		(0.1		)	394.5
Total fixed income securities	1,403.9		9.3		(0.5		)	1,412.7		1,614.0		1.1		(0.2		)	1,614.9
Privately-held debt and redeemable preferred stock securities	19.3		37.4		—			56.7		19.1		37.4		—			56.5
Total available-for-sale debt securities	$	1,423.2	$	46.7	$	(0.5	)	$	1,469.4	$	1,633.1	$	38.5	$	(0.2	)	$	1,671.4

Reported as:
Cash equivalents	$	307.5	$	—	$	—		$	307.5	$	290.9	$	—	$	—		$	290.9
Short-term investments	391.5		1.3		—			392.8		733.7		0.5		—			734.2
Long-term investments	704.9		8.0		(0.5		)	712.4		589.4		0.6		(0.2		)	589.8
Other long-term assets	19.3		37.4		—			56.7		19.1		37.4		—			56.5
Total	$	1,423.2	$	46.7	$	(0.5	)	$	1,469.4	$	1,633.1	$	38.5	$	(0.2	)	$	1,671.4

The following table presents the contractual maturities of the Company's total fixed income securities as of June 30, 2020 (in millions):



	Amortized Cost		Estimated Fair Value
Due in less than one year	$	699.0	$	700.3
Due between one and five years	704.9		712.4
Total	$	1,403.9	$	1,412.7

The following tables present the Company's total fixed income securities that were in an unrealized loss position as of June 30, 2020 and December 31, 2019 (in millions):



	As of June 30, 2020
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	9.2	$	—		$	—	$	—	$	9.2	$	—
Corporate debt securities	167.8		(0.5		)	—		—		167.8		(0.5		)
Foreign government debt securities	4.0		—			4.0		—		8.0		—
U.S. government agency securities	6.0		—			—		—		6.0		—
U.S. government securities	15.0		—			—		—		15.0		—
Total fixed income securities	$	202.0	$	(0.5	)	$	4.0	$	—	$	206.0	$	(0.5	)



	As of December 31, 2019
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	21.6	$	—		$	5.2	$	—	$	26.8	$	—
Corporate debt securities	142.6		(0.1		)	2.1		—		144.7		(0.1		)
Foreign government debt securities	4.0		—			4.0		—		8.0		—
U.S. government agency securities	20.0		—			—		—		20.0		—
U.S. government securities	71.6		(0.1		)	—		—		71.6		(0.1		)
Total fixed income securities	$	259.8	$	(0.2	)	$	11.3	$	—	$	271.1	$	(0.2	)

For available-for-sale debt securities that have unrealized losses, the Company assesses impairment by evaluating various factors, including whether (i) it has the intention to sell any of these investments and (ii) whether it is more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. The Company periodically assesses performance indicators of the investment by evaluating various factors such as (i) changes in the credit ratings and (ii) review of the issuer. As of June 30, 2020, the Company had 121 investments in unrealized loss positions. The gross unrealized losses related to these investments were primarily due to changes in market interest rates. The Company anticipates that it will recover the entire amortized cost basis of such available-for-sale debt securities and has determined that no allowance for credit losses was required to be recognized during the three and six months ended June 30, 2020 and June 30, 2019.

During the three and six months ended June 30, 2020 and June 30, 2019, there were no material gross realized gains or losses from available-for-sale debt securities.

Investments in Equity Securities

The following table presents the Company's investments in equity securities as of June 30, 2020 and December 31, 2019 (in millions):



	As of
	June 30, 2020		December 31, 2019
Equity investments with readily determinable fair value
Money market funds	$	759.0	$	446.4
Mutual funds	25.2		26.8
Publicly-traded equity securities	4.8		3.8
Equity investments without readily determinable fair value	135.0		133.3
Total equity securities	$	924.0	$	610.3

Reported as:
Cash equivalents	$	755.0	$	442.3
Short-term investments	4.8		3.8
Prepaid expenses and other current assets	7.2		4.1
Other long-term assets	157.0		160.1
Total	$	924.0	$	610.3

For the three and six months ended June 30, 2020 and June 30, 2019, there were no material unrealized gains or losses recognized for equity investments.

Restricted Cash and Investments

The Company has restricted cash and investments for: (i) amounts held in escrow accounts, as required in connection with certain acquisitions completed primarily between 2015 and 2019; (ii) amounts held under the Company's short-term disability plan in California; and (iii) amounts under the Company's non-qualified deferred compensation plan for senior-level employees. Restricted investments consist of equity investments. As of June 30, 2020, the carrying value of restricted cash and investments was $90.1 million, of which $68.0 million was included in prepaid expenses and other current assets, and $22.1 million was included in other long-term assets on the Condensed Consolidated Balance Sheet.

The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Condensed Consolidated Balance Sheets as of June 30, 2020 and December 31, 2019 (in millions):



	As of
	June 30, 2020		December 31, 2019
Cash and cash equivalents	$	1,460.3	$	1,215.8
Restricted cash included in Prepaid expenses and other current assets	60.9		60.7
Total cash, cash equivalents, and restricted cash	$	1,521.2	$	1,276.5

Fair Value Measurements

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

Note 3. Fair Value Measurements

Assets and Liabilities Measured at Fair Value on a Recurring Basis

The following table provides a summary of assets and liabilities measured at fair value on a recurring basis and as reported in the Condensed Consolidated Balance Sheets (in millions):



	Fair Value Measurements at June 30, 2020										Fair Value Measurements at December 31, 2019
	Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total			Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total
Assets:
Available-for-sale debt securities:
Asset-backed securities	$	—	$	74.4		$	—	$	74.4		$	—	$	81.4		$	—	$	81.4
Certificates of deposit	—		34.6			—		34.6			—		38.6			—		38.6
Commercial paper	—		74.2			—		74.2			—		168.2			—		168.2
Corporate debt securities	—		594.8			—		594.8			—		605.5			—		605.5
Foreign government debt securities	—		8.0			—		8.0			—		11.4			—		11.4
Time deposits	—		169.9			—		169.9			—		226.3			—		226.3
U.S. government agency securities	—		51.8			—		51.8			—		89.0			—		89.0
U.S. government securities	261.5		143.5			—		405.0			318.9		75.6			—		394.5
Privately-held debt and redeemable preferred stock securities	—		—			56.7		56.7			—		—			56.5		56.5
Total available-for-sale debt securities	261.5		1,151.2			56.7		1,469.4			318.9		1,296.0			56.5		1,671.4
Equity securities:
Money market funds	759.0		—			—		759.0			446.4		—			—		446.4
Mutual funds	25.2		—			—		25.2			26.8		—			—		26.8
Publicly-traded equity securities	4.8		—			—		4.8			3.8		—			—		3.8
Total equity securities	789.0		—			—		789.0			477.0		—			—		477.0
Derivative assets:
Foreign exchange contracts	—		5.7			—		5.7			—		2.5			—		2.5
Interest rate contracts	—		33.7			—		33.7			—		—			—		—
Total derivative assets	—		39.4			—		39.4			—		2.5			—		2.5
Total assets measured at fair value on a recurring basis	$	1,050.5	$	1,190.6		$	56.7	$	2,297.8		$	795.9	$	1,298.5		$	56.5	$	2,150.9
Liabilities:
Derivative liabilities:
Foreign exchange contracts	$	—	$	(11.6	)	$	—	$	(11.6	)	$	—	$	(6.8	)	$	—	$	(6.8	)
Interest rate contracts	—		(2.6		)	—		(2.6		)	—		(3.1		)	—		(3.1		)
Total derivative liabilities	—		(14.2		)	—		(14.2		)	—		(9.9		)	—		(9.9		)
Total liabilities measured at fair value on a recurring basis	$	—	$	(14.2	)	$	—	$	(14.2	)	$	—	$	(9.9	)	$	—	$	(9.9	)



	Fair Value Measurements at June 30, 2020										Fair Value Measurements at December 31, 2019
	Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total			Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total

Total assets, reported as:
Cash equivalents	$	755.0	$	307.5		$	—	$	1,062.5		$	442.3	$	290.9		$	—	$	733.2
Short-term investments	122.6		275.0			—		397.6			188.8		549.2			—		738.0
Long-term investments	143.7		568.7			—		712.4			133.9		455.9			—		589.8
Prepaid expenses and other current assets	7.1		5.7			—		12.8			4.1		2.5			—		6.6
Other long-term assets	22.1		33.7			56.7		112.5			26.8		—			56.5		83.3
Total assets measured at fair value	$	1,050.5	$	1,190.6		$	56.7	$	2,297.8		$	795.9	$	1,298.5		$	56.5	$	2,150.9

Total liabilities, reported as:
Other accrued liabilities	$	—	$	(11.6	)	$	—	$	(11.6	)	$	—	$	(6.8	)	$	—	$	(6.8	)
Other long-term liabilities	—		(2.6		)	—		(2.6		)	—		(3.1		)	—		(3.1		)
Total liabilities measured at fair value on a recurring basis	$	—	$	(14.2	)	$	—	$	(14.2	)	$	—	$	(9.9	)	$	—	$	(9.9	)

The Company's Level 2 available-for-sale debt securities are priced using quoted market prices for similar instruments or non-binding market prices that are corroborated by observable market data. The Company uses inputs such as actual trade data, benchmark yields, broker/dealer quotes, or alternative pricing sources with reasonable levels of price transparency, which are obtained from quoted market prices, independent pricing vendors, or other sources, to determine the ultimate fair value of these assets. The Company's derivative instruments are classified as Level 2, as they are not actively traded and are valued using pricing models that use observable market inputs. During the three and six months ended June 30, 2020, the Company had no transfers into or out of Level 3 of the fair value hierarchy of its assets or liabilities measured at fair value.

The Company's privately-held debt and redeemable preferred stock securities are classified as Level 3 assets due to the lack of observable inputs to determine fair value. The Company estimates the fair value of its privately-held debt and redeemable preferred stock securities on a recurring basis using an analysis of the financial condition and near-term prospects of the investee, including recent valuations at the time of financing activities and the investee's capital structure. During the three and six months ended June 30, 2020, there were no significant activities related to privately-held debt and redeemable preferred stock securities.

Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis

The Company's investments in equity securities without readily determinable fair value are classified as Level 3 assets due to the lack of observable inputs to determine fair value. The Company estimates the fair value on a nonrecurring basis (i.e. when an observable transaction occurs) using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. As of June 30, 2020, there have been no material upward or downward adjustments for price changes to the equity securities without readily determinable fair value.

Certain of the Company's assets, including intangible assets and goodwill, are measured at fair value on a nonrecurring basis. There were no significant impairment charges recognized during the three and six months ended June 30, 2020.

As of June 30, 2020 and December 31, 2019, the Company had no liabilities required to be measured at fair value on a nonrecurring basis.

Assets and Liabilities Not Measured at Fair Value

The carrying amounts of the Company's accounts receivable, accounts payable, and other accrued liabilities approximate fair value due to their short maturities. As of June 30, 2020 and December 31, 2019, the estimated fair value of the Company's total outstanding debt in the Condensed Consolidated Balance Sheets was $1,950.1 million and $1,852.1 million, respectively, based on observable market inputs (Level 2). The carrying value of the promissory note issued to the Company in connection with the previously completed sale of Junos Pulse, along with the accumulated interest paid in kind, of $87.4 million and $78.9 million approximates its fair value as of June 30, 2020 and December 31, 2019, respectively. Notes receivable are generally classified as Level 3 assets due to the lack of observable inputs to determine fair value. The carrying value of a contract manufacturer deposit of $62.3 million, reported within other long-term assets, in the Condensed Consolidated Balance Sheets approximates its fair value as of June 30, 2020. See Note 5, Other Financial Information, for further information on the contract manufacturer deposit.

- Definition

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

+ References + Details

Derivative Instruments

6 Months Ended

Jun. 30, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative Instruments

Note 4. Derivative Instruments

The Company uses derivative instruments to manage a variety of risks, including risks related to fluctuations in foreign currency exchange rates and interest rates on debt instruments. We do not use derivative financial instruments for speculative purposes.

The notional amount of the Company's derivatives is summarized as follows (in millions):



	As of
	June 30, 2020		December 31, 2019
Designated derivatives:
Cash flow hedges:
Foreign currency contracts	$	794.9	$	484.0
Interest rate lock contracts	550.0		—
Fair value hedges:
Interest rate swap contracts	300.0		300.0
Total designated derivatives	1,644.9		784.0

Non-designated derivatives	182.3		162.9
Total	$	1,827.2	$	946.9

The fair value of derivative instruments on the Consolidated Balance Sheets was as follows:



		As of
	Balance Sheet Classification	June 30, 2020		December 31, 2019
Derivative assets:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other current assets	$	1.8	$	2.2
Foreign currency contracts	Other long-term assets	3.7		0.3
Interest rate lock contracts	Other long-term assets	1.4		—
Interest rate swap contracts	Other long-term assets	32.3		—
Total derivatives designated as hedging instruments		$	39.2	$	2.5
Derivatives not designated as hedging instruments	Other current assets	0.2		—
Total derivative assets		$	39.4	$	2.5
Derivative liabilities:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other accrued liabilities	$	9.7	$	6.6
Foreign currency contracts	Other long-term liabilities	1.7		—
Interest rate lock contracts	Other long-term liabilities	2.6		—
Interest rate swap contracts	Other long-term liabilities	—		3.1
Total derivatives designated as hedging instruments		$	14.0	$	9.7
Derivatives not designated as hedging instruments	Other accrued liabilities	0.2		0.2
Total derivative liabilities		$	14.2	$	9.9

Designated Derivatives

The Company uses foreign currency forward contracts to hedge the Company's planned cost of revenues and operating expenses denominated in foreign currencies. These derivatives are designated as cash flow hedges and typically have maturities of thirty-six months or less.

During the three months ended June 30, 2020, the Company entered into interest rate locks with large financial institutions, which fixed benchmark interest rates of future debt issuance for an aggregate notional amount of $550.0 million. The swaps are designated as cash flow hedges and are expected to terminate within 5 years and 3 months.

In 2019, the Company entered into interest rate swaps with an aggregate notional amount of $300.0 million designated as fair value hedges of our fixed-rate 2041 Notes. These swaps convert the fixed interest rates of the notes to floating interest rates based on the LIBOR. Most of the interest rate swaps will expire within ten years or less.

Effect of Derivative Instruments on the Consolidated Statements of Operations

For cash flow hedges, the Company recognized an unrealized gain of $17.9 million and an unrealized loss of $11.2 million in accumulated other comprehensive income for the effective portion of its derivative instruments for the three and six months ended June 30, 2020, respectively. The Company recognized an unrealized loss of $2.1 million and an unrealized gain of $1.3 million in accumulated other comprehensive income for the effective portion of its derivative instruments for the three and six months ended June 30, 2019, respectively.

For foreign currency forward contracts, the company reclassified a loss of $6.9 million and $8.3 million out of accumulated other comprehensive income to cost of revenues and operating expenses in the Condensed Consolidated Statements of Operations during the three and six months ended June 30, 2020, respectively, and a gain of $0.3 million and loss of $0.7 million for the comparable periods ended June 30, 2019, respectively. As of June 30, 2020, an estimated $7.9 million of unrealized net loss within accumulated other comprehensive loss is expected to be reclassified into earnings within the next twelve months.

Non-Designated Derivatives

The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the remeasurement of certain monetary assets and liabilities denominated in foreign currencies. These foreign exchange forward contracts typically have maturities of approximately one to four months. The outstanding non-designated derivative instruments are carried at fair value. Changes in the fair value of these derivatives, which were recorded in other expense, net within the Condensed Consolidated Statements of Operations, were not material during the three and six months ended June 30, 2020 and June 30, 2019.

Other Financial Information

6 Months Ended

Jun. 30, 2020

Other Financial Information [Abstract]

Other Financial Information

Note 5. Other Financial Information

Inventory

Total inventory consisted of the following (in millions):



	As of
	June 30, 2020		December 31, 2019
Production and service materials	$	92.8	$	69.0
Finished goods	30.9		25.2
Inventory	$	123.7	$	94.2

Reported as:
Prepaid expenses and other current assets	$	118.0	$	90.6
Other long-term assets	5.7		3.6
Total	$	123.7	$	94.2

Deposit

The Company has a non-interest bearing deposit balance of $62.3 million, net of an unamortized discount balance of $4.0 million, to a contract manufacturer. The discount is calculated based on an imputed interest rate of 5.0% at June 30, 2020. The imputed interest will be amortized over the term of the deposit to interest income along with a corresponding charge to cost of revenues. The deposit is classified as other long-term assets on the Condensed Consolidated Balance Sheets.

Warranties

Changes during the six months ended June 30, 2020 in the Company’s warranty reserve as reported within other accrued liabilities in the Condensed Consolidated Balance Sheets were as follows (in millions):



Balance as of December 31, 2019	$	31.4
Provisions made during the period	18.6
Actual costs incurred during the period	(19.8		)
Balance as of June 30, 2020	$	30.2

Deferred Revenue

Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):



	As of
	June 30, 2020			December 31, 2019
Deferred product revenue:
Undelivered product commitments and other product deferrals	$	125.9		$	141.7
Deferred gross product revenue	125.9			141.7
Deferred cost of product revenue	(9.6		)	(9.1		)
Deferred product revenue, net	116.3			132.6
Deferred service revenue	1,095.3			1,090.8
Total	$	1,211.6		$	1,223.4
Reported as:
Current	$	834.5		$	812.9
Long-term	377.1			410.5
Total	$	1,211.6		$	1,223.4

Revenue

See Note 10, Segments, for disaggregated revenue by product and service, customer vertical, and geographic region.

Product revenue of $18.1 million and $48.4 million included in deferred revenue at January 1, 2020 was recognized during the three and six months ended June 30, 2020, respectively. Service revenue of $190.8 million and $473.0 million included in deferred revenue at January 1, 2020 was recognized during the three and six months ended June 30, 2020, respectively.

The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of June 30, 2020 and when the Company expects to recognize the amounts as revenue (in millions):



	Revenue Recognition Expected by Period
	Total		Less than 1 year		1-3 years		More than 3 years
Product	$	125.9	$	104.4	$	19.1	$	2.4
Service^(*)	1,106.5		742.8		306.3		57.4
Total	$	1,232.4	$	847.2	$	325.4	$	59.8

________________________________


^(*)	Represents unearned service revenue allocated to the performance obligations not delivered or partially delivered as of June 30, 2020. The unearned service revenue is comprised of deferred revenue and unbilled revenue.

Deferred Commissions

Deferred commissions were $24.9 million as of June 30, 2020. For the three and six months ended June 30, 2020, amortization expense for the deferred commissions was $28.2 million and $57.6 million, respectively, and there were no impairment charges recognized.

Other (Expense) Income, Net

Other (expense) income, net, consisted of the following (in millions):



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Interest income	$	9.3		$	19.8		$	24.4		$	43.3
Interest expense	(19.3		)	(22.0		)	(39.5		)	(46.2		)
Gain (loss) on investments, net	6.5			(2.8		)	0.7			(1.2		)
Other	(0.9		)	0.4			(1.1		)	1.3
Other (expense) income, net	$	(4.4	)	$	(4.6	)	$	(15.5	)	$	(2.8	)

Restructuring Charges

6 Months Ended

Jun. 30, 2020

Restructuring and Related Activities [Abstract]

Restructuring Charges

Note 6. Restructuring Charges

During the first quarter of 2020, the Company initiated a restructuring plan (the "2020 Restructuring Plan") designed to realign its workforce with the Company's sales strategy, enhance productivity and cost efficiencies, and enable reinvestment in certain key priority areas. During the second quarter of 2020, the Company amended the 2020 Restructuring Plan and undertook further actions that resulted in additional severance costs.

During the three months ended June 30, 2020, the Company recorded $4.8 million in severance costs related to workforce reductions. During the six months ended June 30, 2020, the Company recorded $8.9 million in severance and $5.3 million in impairment charges included in other exit related costs, which were reported as restructuring charges in the Condensed Consolidated Statements of Operations.

Restructuring liabilities are reported within other accrued liabilities in the Condensed Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liabilities for the Company's 2020 and prior year restructuring plan (in millions):



	December 31, 2019		Charges		Cash Payments			Other			June 30, 2020
Severance	$	0.7	$	8.9	$	(4.2	)	$	(0.5	)	$	4.9
Other	—		5.3		—			(5.3		)	—
Total	$	0.7	$	14.2	$	(4.2	)	$	(5.8	)	$	4.9

The Company expects to substantially pay the remaining restructuring liabilities by the end of the fourth quarter of 2020.

Debt

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Debt

Note 7. Debt

Debt

The following table summarizes the Company's total debt (in millions, except percentages):



	As of June 30, 2020
	Issuance date	Maturity Date	Amount			Effective Interest Rates
Senior Notes ("Notes"):
4.500% fixed-rate notes("2024 Notes")	March 2014	March 2024	$	350.0		4.63	%
4.500% fixed-rate notes("2024 Notes")	February 2016	March 2024	150.0			4.87	%
4.350% fixed-rate notes ("2025 Notes")	March 2015	June 2025	300.0			4.47	%
3.750% fixed-rate notes ("2029 Notes")	August 2019	August 2029	500.0			3.86	%
5.950% fixed-rate notes ("2041 Notes")	March 2011	March 2041	400.0			6.03	%
Total Notes			1,700.0
Unaccreted discount and debt issuance costs			(12.2		)
Hedge accounting fair value adjustments^(*)			32.3
Total			$	1,720.1

________________________________


^(*)	Represents the fair value adjustments for interest rate swap contracts with an aggregate notional amount of $300.0 million designated as fair value hedges of our fixed-rate 2041 Notes. See Note 4, Derivative Instruments, for a discussion of the Company's interest rate swaps.

The Notes above are the Company’s senior unsecured and unsubordinated obligations, ranking equally in right of payment to all of the Company’s existing and future senior unsecured and unsubordinated indebtedness, and senior in right of payment to any of the Company’s future indebtedness that is expressly subordinated to the Notes.

Interest on the Notes is payable in cash semiannually. The effective interest rates for the Notes include the interest on the Notes, accretion of the discount, and amortization of issuance costs. The indentures that govern the Notes also contain various covenants, including limitations on the Company's ability to incur liens or enter into sale-leaseback transactions over certain dollar thresholds.

As of June 30, 2020, the Company was in compliance with all covenants in the indentures governing the Notes.

Revolving Credit Facility

The Company has an unsecured revolving credit facility that will expire in April 2024, which enables borrowings of up to $500.0 million, with an option to increase the amount of the credit facility by up to an additional $200.0 million, subject to the lenders' approval. The credit facility will terminate in April 2024, subject to a one-year maturity extension option. As of June 30, 2020, we were in compliance with all covenants and no amounts were outstanding under our credit facility.

Equity

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Equity

Note 8. Equity

The following table summarizes dividends paid, stock repurchases, and retirements under the Company's stock repurchase program (in millions, except per share amounts):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Dividends
Per share	$	0.20	$	0.19	$	0.40	$	0.38
Amount	$	66.3	$	65.5	$	131.8	$	131.7

Repurchased under the 2018 Stock Repurchase Program
Shares	—		8.6		10.3		8.6
Average price per share^(*)	$	—	$	27.94	$	23.83	$	27.94
Amount	$	—	$	300.0	$	200.0	$	300.0

________________________________

^(*)

During the six months ended June 30, 2020, the $23.83 average price per share includes $200.0 million in open market purchases, and settlement of the forward contract of $40.0 million under the ASR, which was initiated during the fourth quarter of 2019. During the three and six months ended June 30, 2019, the $27.94 average price per share excludes the forward contract of $60.0 million under the ASR, which was initiated and settled during the second and the third quarter of 2019, respectively.

Cash Dividends on Shares of Common Stock

During the three and six months ended June 30, 2020, the Company declared a quarterly cash dividend of $0.20 per share of common stock on January 27, 2020 and April 28, 2020, respectively, which was paid on March 23, 2020 and June 22, 2020, respectively, to stockholders of record on March 2, 2020 and June 1, 2020. Any future dividends, and the establishment of record and payment dates, are subject to approval by the Board of Directors (the “Board”) of Juniper or an authorized committee thereof. See Note 14, Subsequent Events, for discussion of the Company's dividend declaration subsequent to June 30, 2020.

Stock Repurchase Activities

In January 2018, the Board approved a $2.0 billion share repurchase program ("2018 Stock Repurchase Program"), which replaced our prior authorization. In October 2019, the Board authorized a $1.0 billion increase to the 2018 Stock Repurchase Program for a total of $3.0 billion.

In October 2019, the Company entered into an ASR, to repurchase an aggregate of approximately $200.0 million of the Company’s outstanding common stock. During the three months ended December 31, 2019, the Company made an up-front payment of $200.0 million pursuant to the ASR and received and retired an initial 6.4 million shares of the Company’s common stock for an aggregate price of $160.0 million, based on the market price of $25.15 per share of the Company’s common stock on the date of the transaction. During the three months ended March 31, 2020, the ASR was completed, and an additional 1.8 million shares were received for a total repurchase of 8.2 million shares of the Company's common stock at a volume weighted average repurchase price, less an agreed upon discount, of $24.44 per share. The shares received by the Company were retired, accounted for as a reduction to stockholder’s equity in the Condensed Consolidated Balance Sheets, and treated as a repurchase of common stock for purposes of calculating earnings per share.

During the six months ended June 30, 2020, the Company also repurchased 8.5 million shares of its common stock in the open market for an aggregate purchase price of $200.0 million at an average price of $23.70 per share, under the 2018 Stock Repurchase Program.

As of June 30, 2020, there was approximately $1.5 billion of authorized funds remaining under the 2018 Stock Repurchase Program.

Future share repurchases under the 2018 Stock Repurchase Program will be subject to a review of the circumstances at that time and will be made from time to time in private transactions or open market purchases as permitted by securities laws and other legal requirements. The Company's 2018 Stock Repurchase Program may be discontinued at any time.

In addition to repurchases under the 2018 Stock Repurchase Program, the Company also withholds shares of common stock from certain employees in connection with the vesting of stock awards issued to such employees to satisfy applicable tax withholding requirements. Such withheld shares are treated as common stock repurchases in our financial statements as they reduce the number of shares that would have been issued upon vesting. Repurchases associated with tax withholdings were not material during the three and six months ended June 30, 2020 and June 30, 2019.

Accumulated Other Comprehensive Loss, Net of Tax

The components of accumulated other comprehensive loss, net of related taxes, for the six months ended June 30, 2020 were as follows (in millions):



	Unrealized Gains/Losses on Available-for- Sale Debt Securities		Unrealized Gains/Losses on Cash Flow Hedges			Foreign Currency Translation Adjustments			Total
Balance as of December 31, 2019	$	29.7	$	(4.3	)	$	(43.9	)	$	(18.5	)
Other comprehensive loss before reclassifications	5.7		(8.8		)	(9.1		)	(12.2		)
Amount reclassified from accumulated other comprehensive loss	0.3		7.5			—			7.8
Other comprehensive loss, net	6.0		(1.3		)	(9.1		)	(4.4		)
Balance as of June 30, 2020	$	35.7	$	(5.6	)	$	(53.0	)	$	(22.9	)

Employee Benefit Plans

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Employee Benefit Plans

Note 9. Employee Benefit Plans

Equity Incentive Plans

The Company has stock-based compensation plans pursuant to which it has granted stock options, restricted stock units (“RSUs”), and performance share awards (“PSAs”). The Company also maintains its 2008 Employee Stock Purchase Plan (the “ESPP”) for all eligible employees. As of June 30, 2020, 15.9 million and 12.9 million shares were available for future issuance under the Company's 2015 Equity Incentive Plan (the "2015 Plan") and the ESPP, respectively. In connection with past acquisitions, the Company has also assumed or substituted stock options, RSUs, restricted stock awards ("RSAs"), and PSAs.

RSU, RSA and PSA Activities

The Company’s RSU, RSA and PSA activity and related information as of and for the six months ended June 30, 2020 were as follows (in millions, except per share amounts and years):



	Outstanding RSUs, RSAs and PSAs
	Number of Shares		Weighted Average Grant-Date Fair Value per Share		Weighted Average Remaining Contractual Term (In Years)	Aggregate Intrinsic Value
Balance as of December 31, 2019	17.5		$	25.30
Granted^(*)	3.2		22.57
Vested	(5.1	)	25.98
Canceled	(1.5	)	25.44
Balance as of June 30, 2020	14.1		$	24.42	1.3	$	321.5

________________________________

^(*)

Includes 2.0 million service-based, 0.8 million performance-based, and 0.4 million market-based RSUs. The number of shares subject to performance-based and market-based conditions represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The grant date fair value of RSUs and PSAs was reduced by the present value of dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested.

Employee Stock Purchase Plan

The following table summarizes employee stock purchases through the ESPP (in millions, except per share amounts):



	Six Months Ended June 30,
	2020		2019
Shares purchased	1.4		1.2
Average exercise price per share	$	19.50	$	22.04

The ESPP provides a 24-month offering period with four 6-month purchase periods. A new 24-month offering period commences every six months. The purchase price for the Company’s common stock under the ESPP is 85% of the lower of the fair market value of the shares at (1) the beginning of the applicable offering period or (2) the end of each 6-month purchase period during such offering period. The ESPP will continue in effect until February 25, 2028, unless terminated earlier under the provisions of the ESPP.

Share-Based Compensation Expense

Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and the ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cost of revenues - Product	$	1.1	$	1.6	$	2.5	$	3.5
Cost of revenues - Service	3.4		4.4		7.6		8.9
Research and development	19.0		26.2		34.2		38.4
Sales and marketing	13.2		15.1		27.0		24.5
General and administrative	7.3		8.4		14.7		14.3
Total	$	44.0	$	55.7	$	86.0	$	89.6

The following table summarizes share-based compensation expense by award type (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Stock options	$	1.8	$	3.2	$	3.7	$	3.3
RSUs, RSAs, and PSAs	37.3		47.7		72.2		76.8
ESPP	4.9		4.8		10.1		9.5
Total	$	44.0	$	55.7	$	86.0	$	89.6

As of June 30, 2020, the total unrecognized compensation cost related to unvested share-based awards was $253.6 million to be recognized over a weighted-average period of 1.60 years.

Segments

6 Months Ended

Jun. 30, 2020

Segment Reporting [Abstract]

Segments

Note 10. Segments

The Company operates in one reportable segment. The Company's chief executive officer, who is the chief operating decision maker, reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance, accompanied by disaggregated information about net revenues by product and service, customer vertical, and geographic region as presented below.

The following table presents net revenues by product and service (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Routing	$	403.2	$	416.9	$	717.7	$	791.6
Switching	208.8		215.6		428.6		392.0
Security	80.3		81.4		154.8		149.0
Total product	692.3		713.9		1,301.1		1,332.6
Total service	394.0		388.6		783.2		771.6
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

The following table presents net revenues by customer vertical (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cloud	$	285.5	$	285.0	$	547.4	$	508.2
Service Provider	436.2		447.2		811.7		882.8
Enterprise	364.6		370.3		725.2		713.2
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

The Company attributes revenues to geographic region based on the customer’s shipping address. The following table presents net revenues by geographic region (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Americas:
United States	$	547.3	$	601.2	$	1,076.7	$	1,077.8
Other	61.5		47.6		111.6		114.6
Total Americas	608.8		648.8		1,188.3		1,192.4
Europe, Middle East, and Africa	294.1		291.9		549.1		578.1
Asia Pacific	183.4		161.8		346.9		333.7
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8981-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (f)
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/topic&trid=2134510

+ Details

Income Taxes

6 Months Ended

Jun. 30, 2020

Income Tax Disclosure [Abstract]

Income Taxes

Note 11. Income Taxes

The following table provides details of income taxes (in millions, except percentages):



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Income before income taxes	$	86.1		$	77.8		$	114.4		$	122.3
Income tax provision	$	24.9		$	31.6		$	32.8		$	45.0
Effective tax rate	28.9		%	40.6		%	28.7		%	36.8		%

The Company’s effective tax rate differs from the federal statutory rate of 21% primarily due to the tax impact of state taxes, geographic mix of earnings including foreign-derived intangible income deductions and global intangible low-taxed income, research and development ("R&D") tax credits, tax audit settlements, nondeductible compensation, cost sharing of stock-based compensation, and other transfer pricing adjustments.

On June 7, 2019, the Ninth Circuit Court of Appeals issued an opinion in Altera Corp. v. Commissioner requiring related parties in an intercompany cost-sharing arrangement to share expenses related to stock-based compensation. On February 10, 2020, Altera appealed this decision to the U.S. Supreme Court, which on June 22, 2020, declined to review the decision. Based on the Supreme Court decision to not review the Ninth Circuit Court’s decision, stock-based compensation is subject to cost sharing, and the Company recorded a $18.2 million charge.

The Company’s effective tax rate during the six months ended June 30, 2020 reflects the cumulative impact of cost sharing for stock-based compensation of $18.2 million referenced above, partially offset by a reduction of income tax reserves of $15.2 million, which includes interest of $1.7 million.

The Company's effective tax rate during the six months ended June 30, 2019 reflected the impact of an international realignment and a related write-down of certain deferred tax assets.

As of June 30, 2020, the total amount of gross unrecognized tax benefits was $152.7 million.

The Company engages in continuous discussions and negotiations with tax authorities regarding tax matters in various jurisdictions. There is a greater than remote likelihood that the balance of the gross unrecognized tax benefits will decrease by a range of approximately $23.0 million to $44.0 million within the next twelve months due to the completion of tax review cycles in various tax jurisdictions and lapses of applicable statutes of limitations.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Net Income Per Share

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Net Income Per Share

Note 12. Net Income per Share

The Company computed basic and diluted net income per share as follows (in millions, except per share amounts):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Numerator:
Net income	$	61.2	$	46.2	$	81.6	$	77.3
Denominator:
Weighted-average shares used to compute basic net income per share	331.0		346.3		330.9		347.2
Dilutive effect of employee stock awards	2.1		2.8		3.8		4.5
Weighted-average shares used to compute diluted net income per share	333.1		349.1		334.7		351.7
Net income per share
Basic	$	0.18	$	0.13	$	0.25	$	0.22
Diluted	$	0.18	$	0.13	$	0.24	$	0.22

Anti-dilutive shares	7.6		6.8		6.1		7.0

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 13. Commitments and Contingencies Commitments Except for the items below, there have been no material changes to the Company's commitments compared to the commitments described in Note 16, Commitments and Contingencies, in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K. Unconditional Purchase Obligations Unconditional purchase obligations consist of agreements that include firm and non-cancelable terms to transfer funds in the future for fixed or minimum amounts or quantities to be purchased at fixed or minimum prices. During the second quarter of 2020, the Company amended its existing Master Services Agreement and certain Statements of Work (collectively, the "Agreement") with International Business Machines Corporation ("IBM"), resulting in a $79.4 million reduction in fees payable to IBM over the remaining initial term of the Agreement. Purchase Commitments with Contract Manufacturers and Suppliers In order to reduce manufacturing lead times and in the interest of having access to adequate component supply, the Company enters into agreements with contract manufacturers and certain suppliers to procure inventory based on the Company's requirements. A significant portion of the Company's purchase commitments arising from these agreements consists of firm and non-cancelable commitments. These purchase commitments totaled $1,524.3 million as of June 30, 2020. The Company establishes a liability in connection with purchase commitments related to quantities in excess of its demand forecasts or obsolete materials charges for components purchased by the contract manufacturers based on the Company’s demand forecast or customer orders. As of June 30, 2020, the Company had accrued $21.3 million based on its estimate of such charges. Legal Proceedings In the ordinary course of business, the Company is subject to various pending and potential investigations, disputes, litigations, and legal proceedings. The Company records an accrual for loss contingencies for legal proceedings when it believes that an unfavorable outcome is both (a) probable and (b) the amount or range of any possible loss is reasonably estimable. The Company intends to aggressively defend itself in any legal matters, and while the outcome of any pending matters is not currently determinable, the Company believes that none of its currently existing claims or proceedings are likely to have a material adverse effect on its financial position. Notwithstanding the foregoing, there are many uncertainties associated with any litigation and these matters or any other third-party claims against the Company may cause the Company to incur costly litigation and/or substantial settlement charges. In addition, the resolution of any intellectual property litigation may require the Company to make royalty payments, which could adversely affect gross margins in future periods. If any of these events were to occur, the Company's business, financial condition, results of operations, and cash flows could be adversely affected. The actual liability in any such matters may be materially different from the Company's estimates, if any, which could result in the need to adjust the liability and record additional expenses.

Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Note 14. Subsequent Events Pulse Note Repayment As described in Note 3, Fair Value Measurements, the Company has a promissory note receivable with a maturity date of September 30, 2022 in connection with the previously completed sale of Junos Pulse. On July 20, 2020, the borrower exercised its prepayment option and paid the outstanding principal along with the accumulated interest, aggregating to $87.7 million, in full. Dividend Declaration On July 28, 2020, the Company announced that the Board declared a cash dividend of $0.20 per share of common stock to be paid on September 22, 2020 to stockholders of record as of the close of business on September 1, 2020.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The Condensed Consolidated Financial Statements of Juniper Networks, Inc. (the “Company” or “Juniper”) were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet as of December 31, 2019 has been derived from the audited Consolidated Financial Statements at that date. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the results that may be expected for the year ending December 31, 2020, or any future period. These Condensed Consolidated Financial Statements and accompanying notes should be read in conjunction with the audited Consolidated Financial Statements and accompanying notes in the Company's Annual Report on Form 10-K for the year ended December 31, 2019 (the "Form 10-K"). We have evaluated all subsequent events through the date these condensed consolidated financial statements were issued.
Use of Estimates	The preparation of the financial statements and related disclosures in accordance with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates under different assumptions or conditions.
Derivatives	The Company records changes in fair value of interest rate locks in accumulated other comprehensive income (loss) in the consolidated balance sheets, in the period of change. When the forecasted transaction occurs, the Company will start to amortize the accumulated gain or losses included as a component of other comprehensive income (loss) related to the interest rate lock cash flow hedges to interest expense. In the event the underlying forecasted transaction does not occur, or it becomes probable that it will not occur, the gain or loss on the related cash flow hedge from accumulated other comprehensive income (loss) will be reclassified to other income and expense within income statement.
Recently Adopted Accounting Standards and Recent Accounting Standards Not Yet Adopted	Recently Adopted Accounting Standards Fair Value Measurement: On January 1, 2020, the Company adopted ASU No. 2018-13 (Topic 820) Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds, and modifies certain disclosure requirements for fair value measurements under ASC 820. The Company adopted the standard under the prospective approach for certain modified or new disclosure requirements, and all other amendments in the standard under the retrospective approach. See Note 3, Fair Value Measurements for required disclosures. Simplifying the Test for Goodwill Impairment: On January 1, 2020, the Company adopted ASU No. 2017-04 (Topic 350) Intangibles—Goodwill and Other: Simplifying the Test for Goodwill Impairment, which removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. Under the amended guidance, a goodwill impairment charge will be recognized for the amount by which the carrying value of a reporting unit exceeds its fair value, not to exceed the carrying amount of goodwill. The Company adopted the standard under the prospective approach. Upon adoption, the standard did not have a material impact on the Consolidated Financial Statements. Credit Losses on Financial Instruments: On January 1, 2020, the Company adopted ASU 2016-13 (Topic 326) Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments, as further clarified by the Financial Accounting Standards Board (the "FASB") through the issuance of additional related ASUs, which requires the measurement and recognition of current expected credit losses for financial assets held at amortized cost. ASU 2016-13 replaces the existing incurred loss impairment model with an expected loss model, which requires the use of forward-looking information to calculate credit loss estimates. It also eliminates the concept of other-than-temporary impairment and requires credit losses related to available-for-sale debt securities to be recorded through an allowance for credit losses rather than as a reduction in the amortized cost basis of the securities. These changes will result in earlier recognition of credit losses. The Company adopted the standard under the modified retrospective approach. Upon adoption, the standard did not have a material impact on the Consolidated Financial Statements. Recent Accounting Standards Not Yet Adopted Reference Rate Reform: In March 2020, the FASB issued ASU No. 2020-04 (Topic 848), Reference Rate Reform - Facilitation of the Effects of Reference Rate Reform on Financial Reporting, which provides temporary optional expedients and exceptions to the existing guidance on contract modifications and hedge accounting to ease the financial reporting burdens related to the expected market transition from the London Interbank Offered Rate (LIBOR) and other interbank offered rates to alternative reference rates, such as the Secured Overnight Financing Rate (SOFR). The standard was effective upon issuance and may generally be applied through December 31, 2022, to any new or amended contracts, hedging relationships, and other transactions that reference LIBOR. The Company is currently evaluating the impact of the transition and disclosure requirements of the standard on its Consolidated Financial Statements. Simplifying the Accounting for Income Taxes: In December 2019, the FASB issued ASU No. 2019-12 (Topic 740) Income Taxes — Simplifying the Accounting for Income Taxes, which enhances and simplifies various aspects related to accounting for income taxes. This ASU is to be applied on a prospective basis with the exception of certain amendments that are to be applied on either a retrospective or modified retrospective basis. The new standard is effective for interim and annual periods beginning after December 15, 2020, with early adoption permitted. The Company is currently evaluating the impact of adoption on its Consolidated Financial Statements.

Cash Equivalents and Investments (Tables)

6 Months Ended

Jun. 30, 2020

Cash Equivalents and Investments [Abstract]

Unrealized gains and losses and fair value of available-for-sale debt securities

The following table summarizes the Company's unrealized gains and losses and fair value of investments designated as available-for-sale debt securities as of June 30, 2020 and December 31, 2019 (in millions):



	As of June 30, 2020									As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
Fixed income securities:
Asset-backed securities	$	73.9	$	0.5	$	—		$	74.4	$	81.3	$	0.1	$	—		$	81.4
Certificates of deposit	34.6		—		—			34.6		38.6		—		—			38.6
Commercial paper	74.2		—		—			74.2		168.2		—		—			168.2
Corporate debt securities	588.8		6.5		(0.5		)	594.8		604.9		0.7		(0.1		)	605.5
Foreign government debt securities	8.0		—		—			8.0		11.4		—		—			11.4
Time deposits	169.9		—		—			169.9		226.3		—		—			226.3
U.S. government agency securities	51.6		0.2		—			51.8		89.0		—		—			89.0
U.S. government securities	402.9		2.1		—			405.0		394.3		0.3		(0.1		)	394.5
Total fixed income securities	1,403.9		9.3		(0.5		)	1,412.7		1,614.0		1.1		(0.2		)	1,614.9
Privately-held debt and redeemable preferred stock securities	19.3		37.4		—			56.7		19.1		37.4		—			56.5
Total available-for-sale debt securities	$	1,423.2	$	46.7	$	(0.5	)	$	1,469.4	$	1,633.1	$	38.5	$	(0.2	)	$	1,671.4

Reported as:
Cash equivalents	$	307.5	$	—	$	—		$	307.5	$	290.9	$	—	$	—		$	290.9
Short-term investments	391.5		1.3		—			392.8		733.7		0.5		—			734.2
Long-term investments	704.9		8.0		(0.5		)	712.4		589.4		0.6		(0.2		)	589.8
Other long-term assets	19.3		37.4		—			56.7		19.1		37.4		—			56.5
Total	$	1,423.2	$	46.7	$	(0.5	)	$	1,469.4	$	1,633.1	$	38.5	$	(0.2	)	$	1,671.4

Maturities of fixed income securities

The following table presents the contractual maturities of the Company's total fixed income securities as of June 30, 2020 (in millions):



	Amortized Cost		Estimated Fair Value
Due in less than one year	$	699.0	$	700.3
Due between one and five years	704.9		712.4
Total	$	1,403.9	$	1,412.7

Available-for-sale securities in unrealized loss position

The following tables present the Company's total fixed income securities that were in an unrealized loss position as of June 30, 2020 and December 31, 2019 (in millions):



	As of June 30, 2020
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	9.2	$	—		$	—	$	—	$	9.2	$	—
Corporate debt securities	167.8		(0.5		)	—		—		167.8		(0.5		)
Foreign government debt securities	4.0		—			4.0		—		8.0		—
U.S. government agency securities	6.0		—			—		—		6.0		—
U.S. government securities	15.0		—			—		—		15.0		—
Total fixed income securities	$	202.0	$	(0.5	)	$	4.0	$	—	$	206.0	$	(0.5	)



	As of December 31, 2019
	Less than 12 Months					12 Months or Greater				Total
	Fair Value		Unrealized Loss			Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
Fixed income securities:
Asset-backed securities	$	21.6	$	—		$	5.2	$	—	$	26.8	$	—
Corporate debt securities	142.6		(0.1		)	2.1		—		144.7		(0.1		)
Foreign government debt securities	4.0		—			4.0		—		8.0		—
U.S. government agency securities	20.0		—			—		—		20.0		—
U.S. government securities	71.6		(0.1		)	—		—		71.6		(0.1		)
Total fixed income securities	$	259.8	$	(0.2	)	$	11.3	$	—	$	271.1	$	(0.2	)

Schedule of investments in equity securities

The following table presents the Company's investments in equity securities as of June 30, 2020 and December 31, 2019 (in millions):



	As of
	June 30, 2020		December 31, 2019
Equity investments with readily determinable fair value
Money market funds	$	759.0	$	446.4
Mutual funds	25.2		26.8
Publicly-traded equity securities	4.8		3.8
Equity investments without readily determinable fair value	135.0		133.3
Total equity securities	$	924.0	$	610.3

Reported as:
Cash equivalents	$	755.0	$	442.3
Short-term investments	4.8		3.8
Prepaid expenses and other current assets	7.2		4.1
Other long-term assets	157.0		160.1
Total	$	924.0	$	610.3

Schedule of reconciliation of cash, cash equivalents and restricted cash

The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Condensed Consolidated Balance Sheets as of June 30, 2020 and December 31, 2019 (in millions):



	As of
	June 30, 2020		December 31, 2019
Cash and cash equivalents	$	1,460.3	$	1,215.8
Restricted cash included in Prepaid expenses and other current assets	60.9		60.7
Total cash, cash equivalents, and restricted cash	$	1,521.2	$	1,276.5

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2020

Fair Value Disclosures [Abstract]

Assets and liabilities measured at fair value on a recurring basis

The following table provides a summary of assets and liabilities measured at fair value on a recurring basis and as reported in the Condensed Consolidated Balance Sheets (in millions):



	Fair Value Measurements at June 30, 2020										Fair Value Measurements at December 31, 2019
	Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total			Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total
Assets:
Available-for-sale debt securities:
Asset-backed securities	$	—	$	74.4		$	—	$	74.4		$	—	$	81.4		$	—	$	81.4
Certificates of deposit	—		34.6			—		34.6			—		38.6			—		38.6
Commercial paper	—		74.2			—		74.2			—		168.2			—		168.2
Corporate debt securities	—		594.8			—		594.8			—		605.5			—		605.5
Foreign government debt securities	—		8.0			—		8.0			—		11.4			—		11.4
Time deposits	—		169.9			—		169.9			—		226.3			—		226.3
U.S. government agency securities	—		51.8			—		51.8			—		89.0			—		89.0
U.S. government securities	261.5		143.5			—		405.0			318.9		75.6			—		394.5
Privately-held debt and redeemable preferred stock securities	—		—			56.7		56.7			—		—			56.5		56.5
Total available-for-sale debt securities	261.5		1,151.2			56.7		1,469.4			318.9		1,296.0			56.5		1,671.4
Equity securities:
Money market funds	759.0		—			—		759.0			446.4		—			—		446.4
Mutual funds	25.2		—			—		25.2			26.8		—			—		26.8
Publicly-traded equity securities	4.8		—			—		4.8			3.8		—			—		3.8
Total equity securities	789.0		—			—		789.0			477.0		—			—		477.0
Derivative assets:
Foreign exchange contracts	—		5.7			—		5.7			—		2.5			—		2.5
Interest rate contracts	—		33.7			—		33.7			—		—			—		—
Total derivative assets	—		39.4			—		39.4			—		2.5			—		2.5
Total assets measured at fair value on a recurring basis	$	1,050.5	$	1,190.6		$	56.7	$	2,297.8		$	795.9	$	1,298.5		$	56.5	$	2,150.9
Liabilities:
Derivative liabilities:
Foreign exchange contracts	$	—	$	(11.6	)	$	—	$	(11.6	)	$	—	$	(6.8	)	$	—	$	(6.8	)
Interest rate contracts	—		(2.6		)	—		(2.6		)	—		(3.1		)	—		(3.1		)
Total derivative liabilities	—		(14.2		)	—		(14.2		)	—		(9.9		)	—		(9.9		)
Total liabilities measured at fair value on a recurring basis	$	—	$	(14.2	)	$	—	$	(14.2	)	$	—	$	(9.9	)	$	—	$	(9.9	)



	Fair Value Measurements at June 30, 2020										Fair Value Measurements at December 31, 2019
	Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total			Quoted Prices in Active Markets For Identical Assets (Level 1)		Significant Other Observable Remaining Inputs (Level 2)			Significant Other Unobservable Remaining Inputs (Level 3)		Total

Total assets, reported as:
Cash equivalents	$	755.0	$	307.5		$	—	$	1,062.5		$	442.3	$	290.9		$	—	$	733.2
Short-term investments	122.6		275.0			—		397.6			188.8		549.2			—		738.0
Long-term investments	143.7		568.7			—		712.4			133.9		455.9			—		589.8
Prepaid expenses and other current assets	7.1		5.7			—		12.8			4.1		2.5			—		6.6
Other long-term assets	22.1		33.7			56.7		112.5			26.8		—			56.5		83.3
Total assets measured at fair value	$	1,050.5	$	1,190.6		$	56.7	$	2,297.8		$	795.9	$	1,298.5		$	56.5	$	2,150.9

Total liabilities, reported as:
Other accrued liabilities	$	—	$	(11.6	)	$	—	$	(11.6	)	$	—	$	(6.8	)	$	—	$	(6.8	)
Other long-term liabilities	—		(2.6		)	—		(2.6		)	—		(3.1		)	—		(3.1		)
Total liabilities measured at fair value on a recurring basis	$	—	$	(14.2	)	$	—	$	(14.2	)	$	—	$	(9.9	)	$	—	$	(9.9	)

Derivative Instruments (Tables)

6 Months Ended

Jun. 30, 2020

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivative instruments

The notional amount of the Company's derivatives is summarized as follows (in millions):



	As of
	June 30, 2020		December 31, 2019
Designated derivatives:
Cash flow hedges:
Foreign currency contracts	$	794.9	$	484.0
Interest rate lock contracts	550.0		—
Fair value hedges:
Interest rate swap contracts	300.0		300.0
Total designated derivatives	1,644.9		784.0

Non-designated derivatives	182.3		162.9
Total	$	1,827.2	$	946.9

Schedule of Derivative Assets at Fair Value

The fair value of derivative instruments on the Consolidated Balance Sheets was as follows:



		As of
	Balance Sheet Classification	June 30, 2020		December 31, 2019
Derivative assets:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other current assets	$	1.8	$	2.2
Foreign currency contracts	Other long-term assets	3.7		0.3
Interest rate lock contracts	Other long-term assets	1.4		—
Interest rate swap contracts	Other long-term assets	32.3		—
Total derivatives designated as hedging instruments		$	39.2	$	2.5
Derivatives not designated as hedging instruments	Other current assets	0.2		—
Total derivative assets		$	39.4	$	2.5
Derivative liabilities:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other accrued liabilities	$	9.7	$	6.6
Foreign currency contracts	Other long-term liabilities	1.7		—
Interest rate lock contracts	Other long-term liabilities	2.6		—
Interest rate swap contracts	Other long-term liabilities	—		3.1
Total derivatives designated as hedging instruments		$	14.0	$	9.7
Derivatives not designated as hedging instruments	Other accrued liabilities	0.2		0.2
Total derivative liabilities		$	14.2	$	9.9

Schedule of Derivative Liabilities at Fair Value

The fair value of derivative instruments on the Consolidated Balance Sheets was as follows:



		As of
	Balance Sheet Classification	June 30, 2020		December 31, 2019
Derivative assets:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other current assets	$	1.8	$	2.2
Foreign currency contracts	Other long-term assets	3.7		0.3
Interest rate lock contracts	Other long-term assets	1.4		—
Interest rate swap contracts	Other long-term assets	32.3		—
Total derivatives designated as hedging instruments		$	39.2	$	2.5
Derivatives not designated as hedging instruments	Other current assets	0.2		—
Total derivative assets		$	39.4	$	2.5
Derivative liabilities:
Derivatives designated as hedging instruments:
Foreign currency contracts	Other accrued liabilities	$	9.7	$	6.6
Foreign currency contracts	Other long-term liabilities	1.7		—
Interest rate lock contracts	Other long-term liabilities	2.6		—
Interest rate swap contracts	Other long-term liabilities	—		3.1
Total derivatives designated as hedging instruments		$	14.0	$	9.7
Derivatives not designated as hedging instruments	Other accrued liabilities	0.2		0.2
Total derivative liabilities		$	14.2	$	9.9

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

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+ Details

Other Financial Information (Tables)

6 Months Ended

Jun. 30, 2020

Other Financial Information [Abstract]

Inventories

Total inventory consisted of the following (in millions):



	As of
	June 30, 2020		December 31, 2019
Production and service materials	$	92.8	$	69.0
Finished goods	30.9		25.2
Inventory	$	123.7	$	94.2

Reported as:
Prepaid expenses and other current assets	$	118.0	$	90.6
Other long-term assets	5.7		3.6
Total	$	123.7	$	94.2

Warranties

Changes during the six months ended June 30, 2020 in the Company’s warranty reserve as reported within other accrued liabilities in the Condensed Consolidated Balance Sheets were as follows (in millions):



Balance as of December 31, 2019	$	31.4
Provisions made during the period	18.6
Actual costs incurred during the period	(19.8		)
Balance as of June 30, 2020	$	30.2

Deferred revenue

Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):



	As of
	June 30, 2020			December 31, 2019
Deferred product revenue:
Undelivered product commitments and other product deferrals	$	125.9		$	141.7
Deferred gross product revenue	125.9			141.7
Deferred cost of product revenue	(9.6		)	(9.1		)
Deferred product revenue, net	116.3			132.6
Deferred service revenue	1,095.3			1,090.8
Total	$	1,211.6		$	1,223.4
Reported as:
Current	$	834.5		$	812.9
Long-term	377.1			410.5
Total	$	1,211.6		$	1,223.4

Performance obligation

The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of June 30, 2020 and when the Company expects to recognize the amounts as revenue (in millions):



	Revenue Recognition Expected by Period
	Total		Less than 1 year		1-3 years		More than 3 years
Product	$	125.9	$	104.4	$	19.1	$	2.4
Service^(*)	1,106.5		742.8		306.3		57.4
Total	$	1,232.4	$	847.2	$	325.4	$	59.8

________________________________

^(*)

Represents unearned service revenue allocated to the performance obligations not delivered or partially delivered as of June 30, 2020. The unearned service revenue is comprised of deferred revenue and unbilled revenue.

Other income (expense), net

Other (expense) income, net, consisted of the following (in millions):



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Interest income	$	9.3		$	19.8		$	24.4		$	43.3
Interest expense	(19.3		)	(22.0		)	(39.5		)	(46.2		)
Gain (loss) on investments, net	6.5			(2.8		)	0.7			(1.2		)
Other	(0.9		)	0.4			(1.1		)	1.3
Other (expense) income, net	$	(4.4	)	$	(4.6	)	$	(15.5	)	$	(2.8	)

Restructuring (Benefits) Charges (Tables)

6 Months Ended

Jun. 30, 2020

Restructuring and Related Activities [Abstract]

Schedule of restructuring liabilities

The following table provides a summary of changes in the restructuring liabilities for the Company's 2020 and prior year restructuring plan (in millions):



	December 31, 2019		Charges		Cash Payments			Other			June 30, 2020
Severance	$	0.7	$	8.9	$	(4.2	)	$	(0.5	)	$	4.9
Other	—		5.3		—			(5.3		)	—
Total	$	0.7	$	14.2	$	(4.2	)	$	(5.8	)	$	4.9

Debt (Tables)

6 Months Ended

Jun. 30, 2020

Debt Disclosure [Abstract]

Summary of total debt

The following table summarizes the Company's total debt (in millions, except percentages):



	As of June 30, 2020
	Issuance date	Maturity Date	Amount			Effective Interest Rates
Senior Notes ("Notes"):
4.500% fixed-rate notes("2024 Notes")	March 2014	March 2024	$	350.0		4.63	%
4.500% fixed-rate notes("2024 Notes")	February 2016	March 2024	150.0			4.87	%
4.350% fixed-rate notes ("2025 Notes")	March 2015	June 2025	300.0			4.47	%
3.750% fixed-rate notes ("2029 Notes")	August 2019	August 2029	500.0			3.86	%
5.950% fixed-rate notes ("2041 Notes")	March 2011	March 2041	400.0			6.03	%
Total Notes			1,700.0
Unaccreted discount and debt issuance costs			(12.2		)
Hedge accounting fair value adjustments^(*)			32.3
Total			$	1,720.1

________________________________

^(*)

Represents the fair value adjustments for interest rate swap contracts with an aggregate notional amount of $300.0 million designated as fair value hedges of our fixed-rate 2041 Notes. See Note 4, Derivative Instruments, for a discussion of the Company's interest rate swaps.

- Definition

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

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+ Details

Equity (Tables)

6 Months Ended

Jun. 30, 2020

Stockholders' Equity Note [Abstract]

Summary of dividends paid and stock repurchases and retirements under stock repurchase program

The following table summarizes dividends paid, stock repurchases, and retirements under the Company's stock repurchase program (in millions, except per share amounts):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Dividends
Per share	$	0.20	$	0.19	$	0.40	$	0.38
Amount	$	66.3	$	65.5	$	131.8	$	131.7

Repurchased under the 2018 Stock Repurchase Program
Shares	—		8.6		10.3		8.6
Average price per share^(*)	$	—	$	27.94	$	23.83	$	27.94
Amount	$	—	$	300.0	$	200.0	$	300.0

________________________________

^(*)

During the six months ended June 30, 2020, the $23.83 average price per share includes $200.0 million in open market purchases, and settlement of the forward contract of $40.0 million under the ASR, which was initiated during the fourth quarter of 2019. During the three and six months ended June 30, 2019, the $27.94 average price per share excludes the forward contract of $60.0 million under the ASR, which was initiated and settled during the second and the third quarter of 2019, respectively.

Components of accumulated other comprehensive loss, net of taxes

The components of accumulated other comprehensive loss, net of related taxes, for the six months ended June 30, 2020 were as follows (in millions):



	Unrealized Gains/Losses on Available-for- Sale Debt Securities		Unrealized Gains/Losses on Cash Flow Hedges			Foreign Currency Translation Adjustments			Total
Balance as of December 31, 2019	$	29.7	$	(4.3	)	$	(43.9	)	$	(18.5	)
Other comprehensive loss before reclassifications	5.7		(8.8		)	(9.1		)	(12.2		)
Amount reclassified from accumulated other comprehensive loss	0.3		7.5			—			7.8
Other comprehensive loss, net	6.0		(1.3		)	(9.1		)	(4.4		)
Balance as of June 30, 2020	$	35.7	$	(5.6	)	$	(53.0	)	$	(22.9	)

Employee Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2020

Share-based Payment Arrangement [Abstract]

Schedule of nonvested share activity

The Company’s RSU, RSA and PSA activity and related information as of and for the six months ended June 30, 2020 were as follows (in millions, except per share amounts and years):



	Outstanding RSUs, RSAs and PSAs
	Number of Shares		Weighted Average Grant-Date Fair Value per Share		Weighted Average Remaining Contractual Term (In Years)	Aggregate Intrinsic Value
Balance as of December 31, 2019	17.5		$	25.30
Granted^(*)	3.2		22.57
Vested	(5.1	)	25.98
Canceled	(1.5	)	25.44
Balance as of June 30, 2020	14.1		$	24.42	1.3	$	321.5

________________________________

^(*)

Includes 2.0 million service-based, 0.8 million performance-based, and 0.4 million market-based RSUs. The number of shares subject to performance-based and market-based conditions represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The grant date fair value of RSUs and PSAs was reduced by the present value of dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested.

Schedule of employee stock purchases through ESPP

The following table summarizes employee stock purchases through the ESPP (in millions, except per share amounts):



	Six Months Ended June 30,
	2020		2019
Shares purchased	1.4		1.2
Average exercise price per share	$	19.50	$	22.04

Schedule of employee service share-based compensation, allocation of recognized period costs

Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and the ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cost of revenues - Product	$	1.1	$	1.6	$	2.5	$	3.5
Cost of revenues - Service	3.4		4.4		7.6		8.9
Research and development	19.0		26.2		34.2		38.4
Sales and marketing	13.2		15.1		27.0		24.5
General and administrative	7.3		8.4		14.7		14.3
Total	$	44.0	$	55.7	$	86.0	$	89.6

Disclosure of share-based compensation arrangements by share-based payment award

The following table summarizes share-based compensation expense by award type (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Stock options	$	1.8	$	3.2	$	3.7	$	3.3
RSUs, RSAs, and PSAs	37.3		47.7		72.2		76.8
ESPP	4.9		4.8		10.1		9.5
Total	$	44.0	$	55.7	$	86.0	$	89.6

Segments (Tables)

6 Months Ended

Jun. 30, 2020

Segment Reporting [Abstract]

Financial information for each segment

The following table presents net revenues by product and service (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Routing	$	403.2	$	416.9	$	717.7	$	791.6
Switching	208.8		215.6		428.6		392.0
Security	80.3		81.4		154.8		149.0
Total product	692.3		713.9		1,301.1		1,332.6
Total service	394.0		388.6		783.2		771.6
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

The following table presents net revenues by customer vertical (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Cloud	$	285.5	$	285.0	$	547.4	$	508.2
Service Provider	436.2		447.2		811.7		882.8
Enterprise	364.6		370.3		725.2		713.2
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

Net revenues by geographic region

The Company attributes revenues to geographic region based on the customer’s shipping address. The following table presents net revenues by geographic region (in millions):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Americas:
United States	$	547.3	$	601.2	$	1,076.7	$	1,077.8
Other	61.5		47.6		111.6		114.6
Total Americas	608.8		648.8		1,188.3		1,192.4
Europe, Middle East, and Africa	294.1		291.9		549.1		578.1
Asia Pacific	183.4		161.8		346.9		333.7
Total	$	1,086.3	$	1,102.5	$	2,084.3	$	2,104.2

Income Taxes (Tables)

6 Months Ended

Jun. 30, 2020

Income Tax Disclosure [Abstract]

Schedule of effective income tax rate reconciliation

The following table provides details of income taxes (in millions, except percentages):



	Three Months Ended June 30,						Six Months Ended June 30,
	2020			2019			2020			2019
Income before income taxes	$	86.1		$	77.8		$	114.4		$	122.3
Income tax provision	$	24.9		$	31.6		$	32.8		$	45.0
Effective tax rate	28.9		%	40.6		%	28.7		%	36.8		%

Net Income Per Share (Tables)

6 Months Ended

Jun. 30, 2020

Earnings Per Share [Abstract]

Schedule of basic and diluted net income per share

The Company computed basic and diluted net income per share as follows (in millions, except per share amounts):



	Three Months Ended June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
Numerator:
Net income	$	61.2	$	46.2	$	81.6	$	77.3
Denominator:
Weighted-average shares used to compute basic net income per share	331.0		346.3		330.9		347.2
Dilutive effect of employee stock awards	2.1		2.8		3.8		4.5
Weighted-average shares used to compute diluted net income per share	333.1		349.1		334.7		351.7
Net income per share
Basic	$	0.18	$	0.13	$	0.25	$	0.22
Diluted	$	0.18	$	0.13	$	0.24	$	0.22

Anti-dilutive shares	7.6		6.8		6.1		7.0

Cash Equivalents and Investments - Available-For-Sale (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Available-for-sale debt securities:
Amortized Cost	$ 1,423.2	$ 1,633.1
Gross Unrealized Gains	46.7	38.5
Gross Unrealized Losses	(0.5)	(0.2)
Estimated Fair Value	1,469.4	1,671.4
Asset-backed securities
Available-for-sale debt securities:
Amortized Cost	73.9	81.3
Gross Unrealized Gains	0.5	0.1
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	74.4	81.4
Certificates of deposit
Available-for-sale debt securities:
Amortized Cost	34.6	38.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	34.6	38.6
Commercial paper
Available-for-sale debt securities:
Amortized Cost	74.2	168.2
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	74.2	168.2
Corporate debt securities
Available-for-sale debt securities:
Amortized Cost	588.8	604.9
Gross Unrealized Gains	6.5	0.7
Gross Unrealized Losses	(0.5)	(0.1)
Estimated Fair Value	594.8	605.5
Foreign government debt securities
Available-for-sale debt securities:
Amortized Cost	8.0	11.4
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	8.0	11.4
Time deposits
Available-for-sale debt securities:
Amortized Cost	169.9	226.3
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	169.9	226.3
U.S. government agency securities
Available-for-sale debt securities:
Amortized Cost	51.6	89.0
Gross Unrealized Gains	0.2	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	51.8	89.0
U.S. government securities
Available-for-sale debt securities:
Amortized Cost	402.9	394.3
Gross Unrealized Gains	2.1	0.3
Gross Unrealized Losses	0.0	(0.1)
Estimated Fair Value	405.0	394.5
Fixed Income securities
Available-for-sale debt securities:
Amortized Cost	1,403.9	1,614.0
Gross Unrealized Gains	9.3	1.1
Gross Unrealized Losses	(0.5)	(0.2)
Estimated Fair Value	1,412.7	1,614.9
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Amortized Cost	19.3	19.1
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	56.7	56.5
Cash equivalents
Available-for-sale debt securities:
Amortized Cost	307.5	290.9
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	307.5	290.9
Short-term investments
Available-for-sale debt securities:
Amortized Cost	391.5	733.7
Gross Unrealized Gains	1.3	0.5
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	392.8	734.2
Long-term investments
Available-for-sale debt securities:
Amortized Cost	704.9	589.4
Gross Unrealized Gains	8.0	0.6
Gross Unrealized Losses	(0.5)	(0.2)
Estimated Fair Value	712.4	589.8
Other long-term assets
Available-for-sale debt securities:
Amortized Cost	19.3	19.1
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0.0	0.0
Estimated Fair Value	$ 56.7	$ 56.5

Cash Equivalents and Investments - Maturities of Fixed Income Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Amortized Cost
Amortized Cost	$ 1,423.2	$ 1,633.1
Estimated Fair Value
Total	1,469.4	1,671.4
Fixed Income Securities
Amortized Cost
Due in less than one year	699.0
Due between one and five years	704.9
Amortized Cost	1,403.9	1,614.0
Estimated Fair Value
Due in less than one year	700.3
Due between one and five years	712.4
Total	$ 1,412.7	$ 1,614.9

Cash Equivalents and Investments - Unrealized Loss Position on Fixed Income Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Unrealized Loss
Less than 12 months, fair value	$ 202.0	$ 259.8
Less than 12 months, unrealized loss	(0.5)	(0.2)
12 months or greater, fair value	4.0	11.3
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	206.0	271.1
Total, unrealizeud loss	(0.5)	(0.2)
Asset-backed securities
Unrealized Loss
Less than 12 months, fair value	9.2	21.6
Less than 12 months, unrealized loss	0.0	0.0
12 months or greater, fair value	0.0	5.2
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	9.2	26.8
Total, unrealizeud loss	0.0	0.0
Corporate debt securities
Unrealized Loss
Less than 12 months, fair value	167.8	142.6
Less than 12 months, unrealized loss	(0.5)	(0.1)
12 months or greater, fair value	0.0	2.1
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	167.8	144.7
Total, unrealizeud loss	(0.5)	(0.1)
Foreign government debt securities
Unrealized Loss
Less than 12 months, fair value	4.0	4.0
Less than 12 months, unrealized loss	0.0	0.0
12 months or greater, fair value	4.0	4.0
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	8.0	8.0
Total, unrealizeud loss	0.0	0.0
U.S. government agency securities
Unrealized Loss
Less than 12 months, fair value	6.0	20.0
Less than 12 months, unrealized loss	0.0	0.0
12 months or greater, fair value	0.0	0.0
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	6.0	20.0
Total, unrealizeud loss	0.0	0.0
U.S. government securities
Unrealized Loss
Less than 12 months, fair value	15.0	71.6
Less than 12 months, unrealized loss	0.0	(0.1)
12 months or greater, fair value	0.0	0.0
12 months or greater, unrealized loss	0.0	0.0
Total, fair value	15.0	71.6
Total, unrealizeud loss	$ 0.0	$ (0.1)

Cash Equivalents and Investments - Narrative (Details)	3 Months Ended		6 Months Ended
Cash Equivalents and Investments - Narrative (Details)	Jun. 30, 2020 USD ($) Investment	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Investment	Jun. 30, 2019 USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Total investments in unrealized loss position \| Investment	121		121
Available-for-sale debt securities, gross realized gain	$ 0	$ 0	$ 0	$ 0
Available-for-sale debt securities, gross realized loss	0	0	0	0
Equity investments, unrealized gains	0	0	0	0
Equity investments, unrealized losses	0	0	0	0
Restricted cash and investments	90,100,000		90,100,000
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	68,000,000.0		68,000,000.0
Other long-term assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	22,100,000		22,100,000
Debt Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Allowance for credit losses	0	0	0	0
Allowance for credit losses	$ 0	$ 0	$ 0	$ 0

Cash Equivalents and Investments - Investments in Equity Securities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments without readily determinable fair value	$ 135.0	$ 133.3
Total equity securities	924.0	610.3
Cash equivalents
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	755.0	442.3
Short-term investments
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	4.8	3.8
Prepaid expenses and other current assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	7.2	4.1
Other long-term assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	157.0	160.1
Money market funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	759.0	446.4
Mutual funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	25.2	26.8
Publicly-traded equity securities
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	$ 4.8	$ 3.8

Cash Equivalents and Investments - Restricted Cash and Investments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 1,460.3	$ 1,215.8
Total cash, cash equivalents, and restricted cash	1,521.2	1,276.5	$ 1,443.4	$ 2,505.8
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 60.9	$ 60.7

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Available-for-sale debt securities:
Available-for-sale debt securities	$ 1,469.4	$ 1,671.4
Derivative assets:
Derivative assets	39.4	2.5
Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	74.4	81.4
Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	34.6	38.6
Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	74.2	168.2
Corporate debt securities
Available-for-sale debt securities:
Available-for-sale debt securities	594.8	605.5
Foreign government debt securities
Available-for-sale debt securities:
Available-for-sale debt securities	8.0	11.4
Time deposits
Available-for-sale debt securities:
Available-for-sale debt securities	169.9	226.3
U.S. government agency securities
Available-for-sale debt securities:
Available-for-sale debt securities	51.8	89.0
U.S. government securities
Available-for-sale debt securities:
Available-for-sale debt securities	405.0	394.5
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Available-for-sale debt securities	56.7	56.5
Money market funds
Equity securities:
Equity securities	759.0	446.4
Publicly-traded equity securities
Equity securities:
Equity securities	4.8	3.8
Fair Value, Measurements, Recurring
Available-for-sale debt securities:
Available-for-sale debt securities	1,469.4	1,671.4
Equity securities:
Equity securities	789.0	477.0
Derivative assets:
Derivative assets	39.4	2.5
Total assets measured at fair value on a recurring basis	2,297.8	2,150.9
Liabilities measured at fair value:
Derivative liabilities	(14.2)	(9.9)
Total liabilities measured at fair value on a recurring basis	(14.2)	(9.9)
Fair Value, Measurements, Recurring \| Foreign exchange contracts
Derivative assets:
Derivative assets	5.7	2.5
Liabilities measured at fair value:
Derivative liabilities	(11.6)	(6.8)
Fair Value, Measurements, Recurring \| Interest rate contracts
Derivative assets:
Derivative assets	33.7	0.0
Liabilities measured at fair value:
Derivative liabilities	(2.6)	(3.1)
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	261.5	318.9
Equity securities:
Equity securities	789.0	477.0
Derivative assets:
Derivative assets	0.0	0.0
Total assets measured at fair value on a recurring basis	1,050.5	795.9
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Total liabilities measured at fair value on a recurring basis	0.0	0.0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1) \| Foreign exchange contracts
Derivative assets:
Derivative assets	0.0	0.0
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1) \| Interest rate contracts
Derivative assets:
Derivative assets	0.0	0.0
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	1,151.2	1,296.0
Equity securities:
Equity securities	0.0	0.0
Derivative assets:
Derivative assets	39.4	2.5
Total assets measured at fair value on a recurring basis	1,190.6	1,298.5
Liabilities measured at fair value:
Derivative liabilities	(14.2)	(9.9)
Total liabilities measured at fair value on a recurring basis	(14.2)	(9.9)
Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2) \| Foreign exchange contracts
Derivative assets:
Derivative assets	5.7	2.5
Liabilities measured at fair value:
Derivative liabilities	(11.6)	(6.8)
Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2) \| Interest rate contracts
Derivative assets:
Derivative assets	33.7	0.0
Liabilities measured at fair value:
Derivative liabilities	(2.6)	(3.1)
Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	56.7	56.5
Equity securities:
Equity securities	0.0	0.0
Derivative assets:
Derivative assets	0.0	0.0
Total assets measured at fair value on a recurring basis	56.7	56.5
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Total liabilities measured at fair value on a recurring basis	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3) \| Foreign exchange contracts
Derivative assets:
Derivative assets	0.0	0.0
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3) \| Interest rate contracts
Derivative assets:
Derivative assets	0.0	0.0
Liabilities measured at fair value:
Derivative liabilities	0.0	0.0
Fair Value, Measurements, Recurring \| Asset-backed securities
Available-for-sale debt securities:
Available-for-sale debt securities	74.4	81.4
Fair Value, Measurements, Recurring \| Asset-backed securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Asset-backed securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	74.4	81.4
Fair Value, Measurements, Recurring \| Asset-backed securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Certificates of deposit
Available-for-sale debt securities:
Available-for-sale debt securities	34.6	38.6
Fair Value, Measurements, Recurring \| Certificates of deposit \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Certificates of deposit \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	34.6	38.6
Fair Value, Measurements, Recurring \| Certificates of deposit \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Commercial paper
Available-for-sale debt securities:
Available-for-sale debt securities	74.2	168.2
Fair Value, Measurements, Recurring \| Commercial paper \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Commercial paper \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	74.2	168.2
Fair Value, Measurements, Recurring \| Commercial paper \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Corporate debt securities
Available-for-sale debt securities:
Available-for-sale debt securities	594.8	605.5
Fair Value, Measurements, Recurring \| Corporate debt securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Corporate debt securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	594.8	605.5
Fair Value, Measurements, Recurring \| Corporate debt securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Foreign government debt securities
Available-for-sale debt securities:
Available-for-sale debt securities	8.0	11.4
Fair Value, Measurements, Recurring \| Foreign government debt securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Foreign government debt securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	8.0	11.4
Fair Value, Measurements, Recurring \| Foreign government debt securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Time deposits
Available-for-sale debt securities:
Available-for-sale debt securities	169.9	226.3
Fair Value, Measurements, Recurring \| Time deposits \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Time deposits \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	169.9	226.3
Fair Value, Measurements, Recurring \| Time deposits \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| U.S. government agency securities
Available-for-sale debt securities:
Available-for-sale debt securities	51.8	89.0
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	51.8	89.0
Fair Value, Measurements, Recurring \| U.S. government agency securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| U.S. government securities
Available-for-sale debt securities:
Available-for-sale debt securities	405.0	394.5
Fair Value, Measurements, Recurring \| U.S. government securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	261.5	318.9
Fair Value, Measurements, Recurring \| U.S. government securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	143.5	75.6
Fair Value, Measurements, Recurring \| U.S. government securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Available-for-sale debt securities	56.7	56.5
Fair Value, Measurements, Recurring \| Privately-held debt and redeemable preferred stock securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Privately-held debt and redeemable preferred stock securities \| Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale debt securities:
Available-for-sale debt securities	0.0	0.0
Fair Value, Measurements, Recurring \| Privately-held debt and redeemable preferred stock securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale debt securities:
Available-for-sale debt securities	56.7	56.5
Fair Value, Measurements, Recurring \| Money market funds
Equity securities:
Equity securities	759.0	446.4
Fair Value, Measurements, Recurring \| Money market funds \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Equity securities:
Equity securities	759.0	446.4
Fair Value, Measurements, Recurring \| Money market funds \| Significant Other Observable Remaining Inputs (Level 2)
Equity securities:
Equity securities	0.0	0.0
Fair Value, Measurements, Recurring \| Money market funds \| Significant Other Unobservable Remaining Inputs (Level 3)
Equity securities:
Equity securities	0.0	0.0
Fair Value, Measurements, Recurring \| Mutual funds
Equity securities:
Equity securities	25.2	26.8
Fair Value, Measurements, Recurring \| Mutual funds \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Equity securities:
Equity securities	25.2	26.8
Fair Value, Measurements, Recurring \| Mutual funds \| Significant Other Observable Remaining Inputs (Level 2)
Equity securities:
Equity securities	0.0	0.0
Fair Value, Measurements, Recurring \| Mutual funds \| Significant Other Unobservable Remaining Inputs (Level 3)
Equity securities:
Equity securities	0.0	0.0
Fair Value, Measurements, Recurring \| Publicly-traded equity securities
Equity securities:
Equity securities	4.8	3.8
Fair Value, Measurements, Recurring \| Publicly-traded equity securities \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Equity securities:
Equity securities	4.8	3.8
Fair Value, Measurements, Recurring \| Publicly-traded equity securities \| Significant Other Observable Remaining Inputs (Level 2)
Equity securities:
Equity securities	0.0	0.0
Fair Value, Measurements, Recurring \| Publicly-traded equity securities \| Significant Other Unobservable Remaining Inputs (Level 3)
Equity securities:
Equity securities	0.0	0.0
Cash equivalents
Available-for-sale debt securities:
Available-for-sale debt securities	307.5	290.9
Cash equivalents \| Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value on a recurring basis	1,062.5	733.2
Cash equivalents \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value on a recurring basis	755.0	442.3
Cash equivalents \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value on a recurring basis	307.5	290.9
Cash equivalents \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value on a recurring basis	0.0	0.0
Short-term investments
Available-for-sale debt securities:
Available-for-sale debt securities	392.8	734.2
Short-term investments \| Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value on a recurring basis	397.6	738.0
Short-term investments \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value on a recurring basis	122.6	188.8
Short-term investments \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value on a recurring basis	275.0	549.2
Short-term investments \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value on a recurring basis	0.0	0.0
Long-term investments
Available-for-sale debt securities:
Available-for-sale debt securities	712.4	589.8
Long-term investments \| Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value on a recurring basis	712.4	589.8
Long-term investments \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value on a recurring basis	143.7	133.9
Long-term investments \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value on a recurring basis	568.7	455.9
Long-term investments \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value on a recurring basis	0.0	0.0
Prepaid expenses and other current assets \| Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value on a recurring basis	12.8	6.6
Prepaid expenses and other current assets \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value on a recurring basis	7.1	4.1
Prepaid expenses and other current assets \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value on a recurring basis	5.7	2.5
Prepaid expenses and other current assets \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value on a recurring basis	0.0	0.0
Other long-term assets \| Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value on a recurring basis	112.5	83.3
Other long-term assets \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value on a recurring basis	22.1	26.8
Other long-term assets \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value on a recurring basis	33.7	0.0
Other long-term assets \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value on a recurring basis	56.7	56.5
Other accrued liabilities \| Fair Value, Measurements, Recurring
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	(11.6)	(6.8)
Other accrued liabilities \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	0.0	0.0
Other accrued liabilities \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	(11.6)	(6.8)
Other accrued liabilities \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	0.0	0.0
Other long-term liabilities \| Fair Value, Measurements, Recurring
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	(2.6)	(3.1)
Other long-term liabilities \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets For Identical Assets (Level 1)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	0.0	0.0
Other long-term liabilities \| Fair Value, Measurements, Recurring \| Significant Other Observable Remaining Inputs (Level 2)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	(2.6)	(3.1)
Other long-term liabilities \| Fair Value, Measurements, Recurring \| Significant Other Unobservable Remaining Inputs (Level 3)
Liabilities measured at fair value:
Total liabilities measured at fair value on a recurring basis	$ 0.0	$ 0.0

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended	6 Months Ended
Fair Value Measurements - Narrative (Details) - USD ($)	Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities without readily determinable fair value, upward adjustment	$ 0	$ 0
Equity securities without readily determinable fair value, downward adjustment	0	0
Goodwill and intangible impairment	0	0
Contract manufacturer deposit (non-interest bearing)	62,300,000	62,300,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	14,200,000	14,200,000	$ 9,900,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	0	0	0
Significant Other Unobservable Remaining Inputs (Level 3) \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	0	0	0
Significant Other Observable Remaining Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total outstanding debt, fair value	1,950,100,000	1,950,100,000	1,852,100,000
Significant Other Observable Remaining Inputs (Level 2) \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	14,200,000	14,200,000	9,900,000
Privately-held debt and redeemable preferred stock securities \| Significant Other Unobservable Remaining Inputs (Level 3) \| Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on investments	0	0
Junos Pulse
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note receivable	$ 87,400,000	$ 87,400,000	$ 78,900,000

Derivative Instruments (Details) - USD ($)	3 Months Ended		6 Months Ended
Derivative Instruments (Details) - USD ($)	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	$ 1,827,200,000		$ 1,827,200,000		$ 946,900,000
Designated as hedge
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	1,644,900,000		1,644,900,000		784,000,000.0
Non-designated derivatives
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	182,300,000		182,300,000		162,900,000
Cash flow hedges
Derivatives, Notional Amount [Line Items]
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	17,900,000	$ (2,100,000)	$ (11,200,000)	$ 1,300,000
Cash flow hedges \| Designated as hedge
Derivatives, Notional Amount [Line Items]
Maturities of cash flow hedge derivatives			36 months
Losses expected to be reclassified into earnings within the next 12 months			$ 7,900,000
Interest rate lock contracts \| Cash flow hedges \| Designated as hedge
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	550,000,000.0		$ 550,000,000.0		0
Swaps designated as cash flow hedges, expected termination period			5 years 3 months
Foreign exchange contracts
Derivatives, Notional Amount [Line Items]
Foreign currency forward contracts, amounts reclassified out of AOCI	(6,900,000)	$ 300,000	$ (8,300,000)	$ (700,000)
Foreign exchange contracts \| Cash flow hedges \| Designated as hedge
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	794,900,000		794,900,000		484,000,000.0
Interest rate swap contracts \| Fair value hedges \| Designated as hedge
Derivatives, Notional Amount [Line Items]
Notional amount of derivatives	$ 300,000,000.0		$ 300,000,000.0		$ 300,000,000.0
Minimum \| Foreign exchange contracts
Derivatives, Notional Amount [Line Items]
Maturities of cash flow hedge derivatives			1 month
Maximum \| Foreign exchange contracts
Derivatives, Notional Amount [Line Items]
Maturities of cash flow hedge derivatives			4 months

Derivative Instruments Fair Value of Derivative Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Derivative assets	$ 39.4	$ 2.5
Derivative liability	14.2	9.9
Designated as hedge
Derivative [Line Items]
Derivative assets	39.2	2.5
Derivative liability	14.0	9.7
Other current assets \| Designated as hedge \| Foreign exchange contracts
Derivative [Line Items]
Derivative assets	1.8	2.2
Other current assets \| Non-designated derivatives
Derivative [Line Items]
Derivative assets	0.2	0.0
Other accrued liabilities \| Designated as hedge \| Foreign exchange contracts
Derivative [Line Items]
Derivative liability	9.7	6.6
Other accrued liabilities \| Non-designated derivatives
Derivative [Line Items]
Derivative liability	0.2	0.2
Other long-term liabilities \| Designated as hedge \| Foreign exchange contracts
Derivative [Line Items]
Derivative liability	1.7	0.0
Other long-term liabilities \| Designated as hedge \| Interest rate lock contracts
Derivative [Line Items]
Derivative liability	2.6	0.0
Other long-term liabilities \| Designated as hedge \| Interest rate swap contracts
Derivative [Line Items]
Derivative liability	0.0	3.1
Other long-term assets \| Designated as hedge \| Foreign exchange contracts
Derivative [Line Items]
Derivative assets	3.7	0.3
Other long-term assets \| Designated as hedge \| Interest rate lock contracts
Derivative [Line Items]
Derivative assets	1.4	0.0
Other long-term assets \| Designated as hedge \| Interest rate swap contracts
Derivative [Line Items]
Derivative assets	$ 32.3	$ 0.0

Other Financial Information - Inventories, Net (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Schedule Of Inventory [Line Items]
Production and service materials	$ 92.8	$ 69.0
Finished goods	30.9	25.2
Inventory	123.7	94.2
Prepaid expenses and other current assets
Schedule Of Inventory [Line Items]
Inventory	118.0	90.6
Other long-term assets
Schedule Of Inventory [Line Items]
Inventory	$ 5.7	$ 3.6

Other Financial Information - Narrative (Details)	3 Months Ended	6 Months Ended
Other Financial Information - Narrative (Details)	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($)
Other Financial Information [Abstract]
Contract manufacturer deposit (non-interest bearing)	$ 62,300,000	$ 62,300,000
Non-interest bearing deposit to contract manufacturer, unamortized discount	4,000,000.0	$ 4,000,000.0
Non-interest bearing deposit to contract manufacturer, imputed interest rate		5.00%
Disaggregation of Revenue [Line Items]
Deferred commission	24,900,000	$ 24,900,000
Amortization of deferred commission	28,200,000	57,600,000
Impairment loss	0	0
Product
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	18,100,000	48,400,000
Service
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	$ 190,800,000	$ 473,000,000.0

Other Financial Information - Warranties (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance as of December 31, 2019	$ 31.4
Provisions made during the period	18.6
Actual costs incurred during the period	(19.8)
Balance as of June 30, 2020	$ 30.2

Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Reported as:
Current	$ 834.5	$ 812.9
Long-term	377.1	410.5
Deferred revenue	1,211.6	1,223.4
Undelivered product commitments and other product deferrals
Deferred product revenue:
Deferred gross product revenue	125.9	141.7
Product
Deferred product revenue:
Deferred gross product revenue	125.9	141.7
Deferred cost of product revenue	(9.6)	(9.1)
Reported as:
Deferred revenue	116.3	132.6
Service
Reported as:
Deferred revenue	$ 1,095.3	$ 1,090.8

Other Financial Information - Revenue (Details) $ in Millions	Jun. 30, 2020 USD ($)
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 1,232.4
Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	125.9
Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	1,106.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	847.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 \| Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 104.4
Revenue recognition expected by period, satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01 \| Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 742.8
Revenue recognition expected by period, satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 325.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 19.1
Revenue recognition expected by period, satisfaction period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01 \| Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 306.3
Revenue recognition expected by period, satisfaction period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 59.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 \| Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 2.4
Revenue recognition expected by period, satisfaction period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01 \| Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 57.4
Revenue recognition expected by period, satisfaction period

Other Financial Information - Revenue - Total (Details) $ in Millions	Jun. 30, 2020 USD ($)
Segment Reporting Information [Line Items]
Revenue recognition expected by period	$ 1,232.4
Product
Segment Reporting Information [Line Items]
Revenue recognition expected by period	125.9
Service
Segment Reporting Information [Line Items]
Revenue recognition expected by period	$ 1,106.5

Other Financial Information - Other Expense, Net (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Other Financial Information [Abstract]
Interest income	$ 9.3	$ 19.8	$ 24.4	$ 43.3
Interest expense	(19.3)	(22.0)	(39.5)	(46.2)
Gain (loss) on investments, net	6.5	(2.8)	0.7	(1.2)
Other	(0.9)	0.4	(1.1)	1.3
Other (expense) income, net	$ (4.4)	$ (4.6)	$ (15.5)	$ (2.8)

Restructuring Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.8	$ 21.4	$ 13.7	$ 36.7
2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Restructuring charges			14.2
2020 Restructuring Plan \| Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4.8		8.9
2020 Restructuring Plan \| Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring charges			5.3
Asset impairment charges			$ 5.3

Restructuring Charges - Changes to Restructuring Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Reserve [Roll Forward]
Charges	$ 4.8	$ 21.4	$ 13.7	$ 36.7
2020 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance			0.7
Charges			14.2
Cash Payments			(4.2)
Other			(5.8)
Restructuring liability, ending balance	4.9		4.9
2020 Restructuring Plan \| Severance
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance			0.7
Charges	4.8		8.9
Cash Payments			(4.2)
Other			(0.5)
Restructuring liability, ending balance	4.9		4.9
2020 Restructuring Plan \| Other Restructuring
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance			0.0
Charges			5.3
Cash Payments			0.0
Other			(5.3)
Restructuring liability, ending balance	$ 0.0		$ 0.0

Debt - Schedule of Debt (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 1,700,000,000.0
Unaccreted discount and debt issuance costs	(12,200,000)
Debt Instrument, Derivative Instruments Fair Value Adjustment	32,300,000
Total	1,720,100,000
Notional amount of derivatives	1,827,200,000	$ 946,900,000
Designated as hedge
Debt Instrument [Line Items]
Notional amount of derivatives	1,644,900,000	784,000,000.0
Designated as hedge \| Fair value hedges \| Interest rate swap contracts
Debt Instrument [Line Items]
Notional amount of derivatives	300,000,000.0	$ 300,000,000.0
Senior notes \| 4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 350,000,000.0
Effective interest rate	4.63%
Stated interest rate	4.50%
Senior notes \| 4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 150,000,000.0
Effective interest rate	4.87%
Stated interest rate	4.50%
Senior notes \| 4.350% fixed-rate notes (2025 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 300,000,000.0
Effective interest rate	4.47%
Stated interest rate	4.35%
Senior notes \| 3.750% fixed-rate notes (2029 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 500,000,000.0
Effective interest rate	3.86%
Stated interest rate	3.75%
Senior notes \| 5.950% fixed-rate notes (2041 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 400,000,000.0
Effective interest rate	6.03%
Stated interest rate	5.95%

Debt - Revolving Credit Facility (Details)	6 Months Ended
Debt - Revolving Credit Facility (Details)	Jun. 30, 2020 USD ($)
Line of Credit Facility [Line Items]
Amount outstanding	$ 1,720,100,000
Unsecured Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Borrowing capacity	500,000,000.0
Increase amount of borrowings, subject to lenders' approval	$ 200,000,000.0
Extension option term	1 year
Amount outstanding	$ 0

Equity - Summary of Dividends Paid and Stock Repurchases and Retirements (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Dividends
Per share (in dollars per share)	$ 0.20	$ 0.19	$ 0.40	$ 0.38
Amount	$ 66.3	$ 65.5	$ 131.8	$ 131.7
Repurchased under the 2018 Stock Repurchase Program
Amount	$ 2.1	240.9	245.3	243.8
Forward contract under ASR		$ 60.0	$ 40.0	$ 60.0
Stock Repurchase Program 2018
Repurchased under the 2018 Stock Repurchase Program
Shares (in shares)	0.0	8.6	10.3	8.6
Average price (in usd per share)	$ 0	$ 27.94	$ 23.83	$ 27.94
Amount	$ 0.0	$ 300.0	$ 200.0	$ 300.0

Equity - Cash Dividends on Shares of Common Stock (Details) - $ / shares	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Stockholders' Equity Note [Abstract]
Cash dividends declared per share of common stock (in dollars per share)	$ 0.20	$ 0.20

Equity - Stock Repurchase Activities (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended	3 Months Ended				6 Months Ended
	Oct. 31, 2019	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jan. 31, 2018
Accelerated Share Repurchases [Line Items]
Payment pursuant to ASR						$ 205,300,000		$ 303,800,000
Common stock received, aggregate price		$ 2,100,000			$ 240,900,000	$ 245,300,000		$ 243,800,000
Stock Repurchase Program 2018
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount	$ 3,000,000,000.0								$ 2,000,000,000.0
Stock repurchase program, increase to authorized amount	1,000,000,000.0
Stock repurchased and retired (in shares)		0.0			8.6	10.3		8.6
Common stock received, aggregate price		$ 0			$ 300,000,000.0	$ 200,000,000.0		$ 300,000,000.0
Stock repurchased (in shares)						8.5
Common stock repurchased, average cost per share (in dollars per share)						$ 23.70
Stock repurchase program, remaining authorized repurchase amount		$ 1,500,000,000				$ 1,500,000,000
Accelerated Share Repurchase Program
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount	$ 200,000,000.0
Payment pursuant to ASR				$ 200,000,000.0
Stock repurchased and retired (in shares)			1.8	6.4			8.2
Common stock received, aggregate price				$ 160,000,000.0
Common stock repurchased under stock repurchase program market price (in usd per share)				$ 25.15
Weighted average repurchase price, stock repurchased and retired during period							$ 24.44

Equity - Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 4,610.6
Balance	4,464.3
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(18.5)
Other comprehensive loss before reclassifications	(12.2)
Amount reclassified from accumulated other comprehensive loss	7.8
Other comprehensive loss, net	(4.4)
Balance	(22.9)
Unrealized Gains/Losses on Available-for- Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	29.7
Other comprehensive loss before reclassifications	5.7
Amount reclassified from accumulated other comprehensive loss	0.3
Other comprehensive loss, net	6.0
Balance	35.7
Unrealized Gains/Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(4.3)
Other comprehensive loss before reclassifications	(8.8)
Amount reclassified from accumulated other comprehensive loss	7.5
Other comprehensive loss, net	(1.3)
Balance	(5.6)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(43.9)
Other comprehensive loss before reclassifications	(9.1)
Amount reclassified from accumulated other comprehensive loss	0.0
Other comprehensive loss, net	(9.1)
Balance	$ (53.0)

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

+ References + Details

Employee Benefit Plans - Equity Incentive Plan (Details) shares in Millions	Jun. 30, 2020 shares
Equity incentive plan 2015
Share-Based Compensation Plans
Number of shares available for future issuance (in shares)	15.9
Employee stock purchase plan 2008
Share-Based Compensation Plans
Number of shares available for future issuance (in shares)	12.9

Employee Benefit Plans - Restricted Stock Unit and Performance Share Award Activities (Details) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares
Service-based RSUs
Number of Shares
Granted (in shares)	2.0
RSUs, RSAs, and PSAs
Number of Shares
Balance at beginning of period (in shares)	17.5
Granted (in shares)	3.2
Vested (in shares)	(5.1)
Canceled (in shares)	(1.5)
Balance at end of period (in shares)	14.1
Weighted Average Grant-Date Fair Value per Share
Balance at beginning of period (in dollars per share) \| $ / shares	$ 25.30
Granted (in dollars per share) \| $ / shares	22.57
Vested (in dollars per share) \| $ / shares	25.98
Canceled (in dollars per share) \| $ / shares	25.44
Balance at end of period (in dollars per share) \| $ / shares	$ 24.42
Weighted average remaining contractual term	1 year 3 months 18 days
Aggregate intrinsic value \| $	$ 321.5
Performance Shares
Number of Shares
Granted (in shares)	0.8
Market-based RSUs
Number of Shares
Granted (in shares)	0.4

Employee Benefit Plans - Employee Stock Purchase Plan (Details) shares in Millions	6 Months Ended
	Jun. 30, 2020 period $ / shares shares	Jun. 30, 2019 $ / shares shares
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
ESPP offering period duration	24 months
ESPP, number of purchase period \| period	4
ESPP. purchase period	6 months
ESPP, purchase price of common stock, percent	85.00%
Employee stock purchase plan 2008
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares purchased (in shares) \| shares	1.4	1.2
Average exercise price per share (in dollars per share) \| $ / shares	$ 19.50	$ 22.04

Employee Benefit Plans - Share Based Compensation by Cost and Expense Categories (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 44.0	$ 55.7	$ 86.0	$ 89.6
Stock options
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	1.8	3.2	3.7	3.3
RSUs, RSAs, and PSAs
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	37.3	47.7	72.2	76.8
ESPP
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	4.9	4.8	10.1	9.5
Cost of revenues - Product
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	1.1	1.6	2.5	3.5
Cost of revenues - Service
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	3.4	4.4	7.6	8.9
Research and development
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	19.0	26.2	34.2	38.4
Sales and marketing
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	13.2	15.1	27.0	24.5
General and administrative
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 7.3	$ 8.4	$ 14.7	$ 14.3

Employee Benefit Plans - Share Based Compensation by Share Based Payment Award Types (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020 USD ($)
Share-based Payment Arrangement [Abstract]
Unrecognized compensation cost	$ 253.6
Unrecognized compensation, weighted average recognition period	1 year 7 months 6 days

Segments - Revenue by Product (Details) $ in Millions	3 Months Ended		6 Months Ended
Segments - Revenue by Product (Details) $ in Millions	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| segment			1
Total net revenues	$ 1,086.3	$ 1,102.5	$ 2,084.3	$ 2,104.2
Product
Segment Reporting Information [Line Items]
Total net revenues	692.3	713.9	1,301.1	1,332.6
Routing
Segment Reporting Information [Line Items]
Total net revenues	403.2	416.9	717.7	791.6
Switching
Segment Reporting Information [Line Items]
Total net revenues	208.8	215.6	428.6	392.0
Security
Segment Reporting Information [Line Items]
Total net revenues	80.3	81.4	154.8	149.0
Service
Segment Reporting Information [Line Items]
Total net revenues	$ 394.0	$ 388.6	$ 783.2	$ 771.6

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Segments - Revenues by Customer Vertical (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total net revenues	$ 1,086.3	$ 1,102.5	$ 2,084.3	$ 2,104.2
Cloud
Segment Reporting Information [Line Items]
Total net revenues	285.5	285.0	547.4	508.2
Service Provider
Segment Reporting Information [Line Items]
Total net revenues	436.2	447.2	811.7	882.8
Enterprise
Segment Reporting Information [Line Items]
Total net revenues	$ 364.6	$ 370.3	$ 725.2	$ 713.2

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Segments - Geographic (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Segments - Geographic (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Total net revenues	$ 1,086.3	$ 1,102.5	$ 2,084.3	$ 2,104.2
Total Americas
Segment Reporting Information [Line Items]
Total net revenues	608.8	648.8	1,188.3	1,192.4
United States
Segment Reporting Information [Line Items]
Total net revenues	547.3	601.2	1,076.7	1,077.8
Other
Segment Reporting Information [Line Items]
Total net revenues	61.5	47.6	111.6	114.6
Europe, Middle East, and Africa
Segment Reporting Information [Line Items]
Total net revenues	294.1	291.9	549.1	578.1
Asia Pacific
Segment Reporting Information [Line Items]
Total net revenues	$ 183.4	$ 161.8	$ 346.9	$ 333.7

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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+ Details

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Contingency [Line Items]
Income before income taxes	$ 86.1	$ 77.8	$ 114.4	$ 122.3
Income tax provision	$ 24.9	$ 31.6	$ 32.8	$ 45.0
Effective tax rate	28.90%	40.60%	28.70%	36.80%
Cumulative impact of cost sharing for stock-based compensation			$ 18.2
Reduction of income tax reserves			(15.2)
Interest benefit included within reduction of income tax reserves			1.7
Unrecognized tax benefits	$ 152.7		152.7
Minimum
Income Tax Contingency [Line Items]
Unrecognized tax benefits could decrease up to	23.0		23.0
Maximum
Income Tax Contingency [Line Items]
Unrecognized tax benefits could decrease up to	$ 44.0		$ 44.0

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net income	$ 61.2	$ 46.2	$ 81.6	$ 77.3
Denominator:
Weighted-average shares used to compute basic net income per share (in shares)	331.0	346.3	330.9	347.2
Dilutive effect of employee stock awards (in shares)	2.1	2.8	3.8	4.5
Weighted-average shares used to compute diluted net income per share (in shares)	333.1	349.1	334.7	351.7
Net income per share
Basic (in dollars per share)	$ 0.18	$ 0.13	$ 0.25	$ 0.22
Diluted, (in dollars per share)	$ 0.18	$ 0.13	$ 0.24	$ 0.22
Anti-dilutive shares (in shares)	7.6	6.8	6.1	7.0

Commitments and Contingencies - Commitments (Details) $ in Millions	Jun. 30, 2020 USD ($)
Loss Contingencies [Line Items]
Purchase obligation	$ 1,524.3
Excess purchase commitments and obsolete materials liability	21.3
Master Service Agreement
Loss Contingencies [Line Items]
Reduction in fees payable	$ 79.4

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended	6 Months Ended
	Jul. 28, 2020	Jul. 20, 2020	Jun. 30, 2020	Jun. 30, 2020
Dividends
Cash dividends declared per share of common stock (in dollars per share)			$ 0.20	$ 0.20
Subsequent Event
Dividends
Cash dividends declared per share of common stock (in dollars per share)	$ 0.20
Junos Pulse \| Subsequent Event
Dividends
Note receivable		$ 87.7