Juniper Networks (JNPR) 10-K 20 Feb 20 2019 FY Annual report Financial data

Cover Page

Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 13, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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 Public Float			$ 9,077,000,000
Entity Common Stock, Shares Outstanding		330,527,200
Documents Incorporated by Reference	As noted herein, the information called for by Part III is incorporated by reference to specified portions of the registrant's definitive proxy statement to be filed in conjunction with the registrant's 2020 Annual Meeting of Stockholders, which is expected to be filed not later than 120 days after the registrant's fiscal year ended December 31, 2019 .
Entity Central Index Key	0001043604
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net revenues:
Net revenues	$ 4,445.4	$ 4,647.5	$ 5,027.2
Cost of revenues:
Cost of revenues	1,828.6	1,906.3	1,955.1
Gross margin	2,616.8	2,741.2	3,072.1
Operating expenses:
Research and development	955.7	1,003.2	980.7
Sales and marketing	939.3	927.4	950.2
General and administrative	244.3	231.1	227.5
Restructuring charges	35.3	7.3	65.6
Total operating expenses	2,174.6	2,169	2,224
Operating income	442.2	572.2	848.1
Other expense, net	(27.8)	(39.5)	(36.3)
Income before income taxes	414.4	532.7	811.8
Income tax provision (benefit)	69.4	(34.2)	505.6
Net income	$ 345	$ 566.9	$ 306.2
Net income per share:
Basic (in dollars per share)	$ 1.01	$ 1.62	$ 0.81
Diluted (in dollars per share)	$ 0.99	$ 1.60	$ 0.80
Shares used in computing net income per share:
Basic (in shares)	343.2	349	377.7
Diluted (in shares)	348.2	354.4	384.2
Product
Net revenues:
Net revenues	$ 2,867.7	$ 3,107.1	$ 3,446.2
Cost of revenues:
Cost of revenues	1,227	1,277.2	1,360.9
Service
Net revenues:
Net revenues	1,577.7	1,540.4	1,581
Cost of revenues:
Cost of revenues	$ 601.6	$ 629.1	$ 594.2

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 345	$ 566.9	$ 306.2
Available-for-sale debt securities:
Change in net unrealized gains and losses, net of tax (provision) benefit of ($1.0), $1.0, and ($4.0) for 2019, 2018, and 2017, respectively	4.6	0.6	4.5
Net realized (gains) losses reclassified into net income, net of tax provisions of $0.1, zero, and $0.9 for 2019, 2018, and 2017, respectively	(0.4)	0.9	(2.1)
Net change on available-for-sale debt securities, net of tax	4.2	1.5	2.4
Cash flow hedges:
Change in net unrealized gains and losses, net of tax (provision) benefit of ($2.6), $2.3, and ($4.4) for 2019, 2018, and 2017, respectively	(8.9)
Change in net unrealized gains and losses, net of tax (provision) benefit of ($2.6), $2.3, and ($4.4) for 2019, 2018, and 2017, respectively		(6.4)	15.7
Net realized losses (gains) reclassified into net income, net of tax provisions of $1.7, $0.3, and $2.4 for 2019, 2018, and 2017, respectively	5.5
Net realized losses (gains) reclassified into net income, net of tax provisions of $1.7, $0.3, and $2.4 for 2019, 2018, and 2017, respectively		(1.2)	(5.2)
Net change on cash flow hedges, net of tax	(3.4)
Net change on cash flow hedges, net of tax		(7.6)	10.5
Change in foreign currency translation adjustments	(1.1)	(12.4)	19
Other comprehensive (loss) income, net of tax	(0.3)	(18.5)	31.9
Comprehensive income	$ 344.7	$ 548.4	$ 338.1

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Change in net unrealized gains and losses, net of tax (provision) benefit of ($1.0), $1.0, and ($4.0) for 2019, 2018, and 2017, respectively	$ (1)	$ 1	$ (4)
Net realized (gains) losses reclassified into net income, net of tax provisions of $0.1, zero, and $0.9 for 2019, 2018, and 2017, respectively	0.1	0	0.9
Change in net unrealized gains and losses, net of tax (provision) benefit of ($2.6), $2.3, and ($4.4) for 2019, 2018, and 2017, respectively	(2.6)
Change in net unrealized gains and losses, net of tax (provision) benefit of ($2.6), $2.3, and ($4.4) for 2019, 2018, and 2017, respectively		2.3	(4.4)
Net realized losses (gains) reclassified into net income, net of tax provisions of $1.7, $0.3, and $2.4 for 2019, 2018, and 2017, respectively	$ 1.7
Net realized losses (gains) reclassified into net income, net of tax provisions of $1.7, $0.3, and $2.4 for 2019, 2018, and 2017, respectively		$ 0.3	$ 2.4

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 1,215.8	$ 2,489
Short-term investments	738	1,070.1
Accounts receivable, net of allowance for doubtful accounts of $5.5 and $4.9 as of December 31, 2019 and 2018, respectively	879.7	754.6
Prepaid expenses and other current assets	376.3	268.1
Total current assets	3,209.8	4,581.8
Property and equipment, net	830.9	951.7
Operating lease assets	169.7
Long-term investments	589.8	199
Purchased intangible assets, net	185.8	118.5
Goodwill	3,337.1	3,108.8
Other long-term assets	514.6	403.5
Total assets	8,837.7	9,363.3
Current liabilities:
Accounts payable	219.5	208.8
Accrued compensation	229	221
Deferred revenue	812.9	829.3
Short-term portion of long-term debt	0	349.9
Other accrued liabilities	282.5	233.5
Total current liabilities	1,543.9	1,842.5
Long-term debt	1,683.9	1,789.1
Long-term deferred revenue	410.5	384.3
Long-term income taxes payable	372.6	404.4
Long-term operating lease liabilities	158.1
Other long-term liabilities	58.1	119.8
Total liabilities	4,227.1	4,540.1
Commitments and contingencies (Note 16)
Stockholders' equity:
Convertible preferred stock, $0.00001 par value; 10.0 shares authorized; none issued and outstanding	0	0
Common stock, $0.00001 par value; 1,000.0 shares authorized; 335.9 shares and 346.4 shares issued and outstanding as of December 31, 2019 and 2018, respectively	0	0
Additional paid-in capital	7,370.5	7,672.8
Accumulated other comprehensive loss	(18.5)	(18.2)
Accumulated deficit	(2,741.4)	(2,831.4)
Total stockholders' equity	4,610.6	4,823.2
Total liabilities and stockholders' equity	$ 8,837.7	$ 9,363.3

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 5.5	$ 4.9
Convertible preferred stock - par value (in USD per share)	$ 0.00001	$ 0.00001
Convertible preferred stock - shares authorized (in shares)	10,000,000	10,000,000
Convertible preferred stock - issued (in shares)	0	0
Convertible preferred stock - outstanding (in shares)	0	0
Common stock - par value (in USD per share)	$ 0.00001	$ 0.00001
Common stock - shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock - shares issued (in shares)	335,900,000	346,400,000
Common stock - outstanding (in shares)	335,900,000	346,400,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 345	$ 566.9	$ 306.2
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	202.2	217.1	187.5
Depreciation, amortization, and accretion	210.3	210.5	225.6
Operating lease assets expense	42	0	0
Loss on extinguishment of debt	15.3	0	0
Deferred income taxes	2.9	42.6	(139.6)
Other	3.5	9.6	(14.5)
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	(118.1)	96.3	203.8
Prepaid expenses and other assets	(100.7)	(70.9)	43
Accounts payable	6.4	3.5	(10.1)
Accrued compensation	6.5	41.4	(42.8)
Income taxes payable	(40.5)	(269.2)	447.3
Other accrued liabilities	(46.8)	(11.4)	(2.1)
Deferred revenue	0.9	24.7	55
Net cash provided by operating activities	528.9	861.1	1,259.3
Cash flows from investing activities:
Purchases of property and equipment	(109.6)	(147.4)	(151.2)
Purchases of available-for-sale debt securities	(3,209.8)	(1,228.5)	(1,882.9)
Proceeds from sales of available-for-sale debt securities	1,520	1,070.2	944
Proceeds from maturities and redemptions of available-for-sale debt securities	1,642.3	910.2	741.6
Purchases of equity securities	(107.1)	(17.5)	(14.9)
Proceeds from sales of equity securities	14.2	36.9	12.4
Proceeds from Pulse note receivable	0	0	75
Payments for business acquisitions, net of cash and cash equivalents acquired	(270.9)	(16.4)	(27)
Subsequent payments related to acquisitions in prior years	(7.3)	(42.7)	0
Net cash (used in) provided by investing activities	(528.2)	564.8	(303)
Cash flows from financing activities:
Repurchase and retirement of common stock	(554.9)	(756.6)	(725.8)
Proceeds from issuance of common stock	55.6	56.9	64.5
Payment of dividends	(260.1)	(249.3)	(150.4)
Payment of debt	(950)	0	0
Issuance of debt, net	495.2	0	0
Payment for debt extinguishment costs	(14.6)	0	0
Change in customer financing arrangement	0	(16.9)	16.9
Other	0	(2.7)	0
Net cash used in financing activities	(1,228.8)	(968.6)	(794.8)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	(1.2)	(10.6)	17
Net increase in cash, cash equivalents, and restricted cash	(1,229.3)	446.7	178.5
Cash, cash equivalents, and restricted cash at beginning of period	1,276.5	2,505.8	2,059.1
Cash, cash equivalents, and restricted cash at end of period	2,505.8	2,059.1	1,880.6
Supplemental disclosures of cash flow information:
Cash paid for interest, net of amounts capitalized	90.6	94	93.9
Cash paid for income taxes, net	$ 98.8	$ 181	$ 193.5

Consolidated Statements of Chan

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
Beginning balance (shares) at Dec. 31, 2016		381.1
Stockholders' equity, Beginning balance at Dec. 31, 2016	$ 4,962.5		$ 8,281.6	$ (37.3)	$ (3,281.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	306.2				306.2
Other comprehensive income (loss), net	31.9			31.9
Issuance of common stock (in shares)		10.7
Issuance of common stock	64.5		64.5
Repurchase and retirement of common stock (in shares)		(26.3)
Repurchase and retirement of common stock	(725.8)		(354.6)		(371.2)
Share-based compensation expense	188.2		188.2
Payment of cash dividends	(150.4)		(150.4)
Ending balance (shares) at Dec. 31, 2017		365.5
Stockholders' equity, Ending balance at Dec. 31, 2017	4,680.9		8,042.1	(5.4)	(3,355.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	566.9				566.9
Other comprehensive income (loss), net	(18.5)			(18.5)
Issuance of common stock (in shares)		10.4
Issuance of common stock	56.9		56.9
Repurchase and retirement of common stock (in shares)		(29.5)
Repurchase and retirement of common stock	(756.6)		(395.1)		(361.5)
Share-based compensation expense	218.2		218.2
Payment of cash dividends	(249.3)		(249.3)
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net	$ 0			5.7	(5.7)
Ending balance (shares) at Dec. 31, 2018	346.4	346.4
Stockholders' equity, Ending balance at Dec. 31, 2018	$ 4,823.2		7,672.8	(18.2)	(2,831.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	345				345
Other comprehensive income (loss), net	(0.3)			(0.3)
Issuance of common stock (in shares)		9.8
Issuance of common stock	55.6		55.6
Common stock assumed upon business combination	4.6		4.6
Repurchase and retirement of common stock (in shares)		(20.3)
Repurchase and retirement of common stock	(514.9)		(264.6)		(250.3)
Share-based compensation expense	202.2		202.2
Payment of cash dividends	(260.1)		(260.1)
Purchase of forward contract under accelerated share repurchase program (ASR)	$ (40)		(40)
Ending balance (shares) at Dec. 31, 2019	335.9	335.9
Stockholders' equity, Ending balance at Dec. 31, 2019	$ 4,610.6		$ 7,370.5	$ (18.5)	$ (2,741.4)

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	Dec. 26, 2019	Sep. 25, 2019	Jun. 24, 2019	Mar. 22, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Payments of cash dividends (in dollars per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.19	$ 0.76	$ 0.72	$ 0.40

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Juniper Networks, Inc. (the “Company” or “Juniper”) designs, develops, and sells products and services for high-performance networks, to enable customers to build scalable, reliable, secure and cost-effective networks for their businesses, while achieving agility and improved operating efficiency through automation. The Company sells high-performance routing, switching, and security networking products and service offerings to customers within its verticals: Cloud, Service Provider, and Enterprise who view the network as critical to their success. Basis of Presentation

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies 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 Consolidated Financial Statements and the accompanying notes. The Company bases its estimates and assumptions on current facts, historical experience, and various other factors that it believes are reasonable under the circumstances, to determine the carrying values of assets and liabilities that are not readily apparent from other sources. To the extent there are material differences between the Company's estimates and the actual results, the Company's future consolidated results of operation may be affected. Cash, Cash Equivalents, and Investments Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, demand deposits with banks, highly liquid investments in money market funds, commercial paper, government securities, certificates of deposits, time deposits, and corporate debt securities, which are readily convertible into cash. All highly liquid investments with original maturities of three months or less from Juniper's purchase date are classified as cash equivalents. Investments in Available-for-Sale Debt Securities The Company's investments in debt securities are classified as available-for-sale and include the Company's fixed income securities and investments in privately-held companies, consisting of debt and redeemable preferred stock securities. Fixed income securities are initially recorded at cost and periodically adjusted to fair value in the Consolidated Balance Sheets. Unrealized gains and losses on these investments are reported as a separate component of accumulated other comprehensive loss in the Consolidated Balance Sheets. Realized gains and losses are determined based on the specific identification method and are reported in the Consolidated Statements of Operations. Fixed income securities primarily consist of asset-backed securities, certificate of deposits, commercial paper, corporate debt securities, time deposits, foreign government debt securities, U.S. government agency securities, and U.S. treasury securities. The Company periodically evaluates these investments to determine if impairment charges are required. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time the investment has been in a loss position, the extent to which the fair value has been less than the Company's cost basis, the investment's financial condition, and the near-term prospects of the investee. If the Company determines that the decline in an investment's value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. The Company's privately-held debt and redeemable preferred stock securities are included in other long-term assets in the Consolidated Balance Sheets and are recorded at fair value. Fair value is reassessed when the Company is made aware of information indicating a change in the enterprise value of the investee, including known acquisition offers, subsequent funding rounds, and investee's plans for liquidation. The Company periodically evaluates these securities for indicators of impairment, including the inability to recover a portion of or the entire carrying amount of the investment, the inability of the investee to sustain earnings, the reduction in or termination of financial commitment to the investee from other investors, the intention to sell the investment, and whether it is more likely than not that the Company will be required to sell the investment before recovery of the entire amortized cost basis. If the Company determines that the decline in an investment's value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. Investments in Equity Securities The Company's investments in equity securities with readily determinable fair values consist of money market funds, the non-qualified compensation plan ("NQDC") that is invested in mutual funds, and investments in public companies. These investments are measured at fair value with changes in fair value recognized in the Consolidated Statements of Operations. Equity securities without readily determinable fair values include the Company's investments in privately-held companies consisting of non-redeemable preferred stock and common stock securities. The Company accounts for these securities at cost, adjusted for changes from observable transactions for identical or similar investments of the same issuer, less impairments. Fair value of these equity securities is reassessed when the Company identifies observable price changes indicating that an adjustment upward or downward to the carrying value is necessary. Any observable changes in fair value are recognized in earnings as of the date that the observable transaction took place, rather than the current reporting date. In addition, the Company periodically evaluates equity securities without readily determinable fair values to determine if impairment charges are required by evaluating whether an event or change in circumstance has occurred that may have a significant adverse effect on the fair value of the investment. A qualitative assessment is performed each reporting period to assess whether there are any impairment indicators, including, but not limited to, significant deterioration in the investee's earnings performance; credit rating; asset quality or business prospects; adverse change in the regulatory, economic, or technological environment; change in the general market condition of the geographic area or industry; acquisition offers; and the ability to continue as a going concern. If such indicators are present, the Company estimates the fair value of impaired investments and recognizes an impairment loss in the Consolidated Statement of Operations equal to the difference between the carrying value and fair value. Fair Value Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it transacts, and considers assumptions that market participants would use when pricing the asset or liability. The Company applies the following fair value hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. These inputs are valued using market-based approaches. Level 3 – Inputs are unobservable inputs based on the Company’s assumptions. These inputs, if any, are valued using internal financial models. Derivative Instruments The Company uses derivative instruments, primarily foreign currency forward and interest rate swap contracts, to hedge certain foreign currency and interest rate exposures. The Company does not enter into derivatives for speculative or trading purposes. The Company uses foreign currency forward contracts to hedge certain forecasted foreign currency transactions relating to operating expenses. These derivatives are designated as cash flow hedges, which are carried at fair value with the derivative's gain or loss is initially reported as a component of accumulated other comprehensive loss, and upon occurrence of the forecasted transaction, is subsequently reclassified into the costs of services or operating expense line item to which the hedged transaction relates. Cash flows from such hedges are classified as operating activities. The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in non-functional currencies. These derivatives are carried at fair value with changes recorded in other expense, net in the Consolidated Statements of Operations in the same period as the changes in the fair value from the re-measurement of the underlying assets and liabilities. Cash flows from such derivatives are classified as operating activities. The Company uses interest rate swaps to convert certain of our fixed interest rate notes to floating interest rates based on the London InterBank Offered Rate (LIBOR). All interest rate swaps will expire within ten years or less. The Company recognizes the change in fair value of the derivative instrument, as well as the offsetting change in the fair value of the hedged item, in Other expense, net in the Consolidated Statements of Operations in the period of change. These derivatives are classified in the Consolidated Statements of Cash Flows in the same section as the underlying item. The Company presents its derivative assets and derivative liabilities on a gross basis in the Consolidated Balance Sheets. However, under agreements containing provisions on netting with certain counterparties of foreign exchange contracts, subject to applicable requirements, the Company is allowed to net-settle transactions on the same date in the same currency, with a single net amount payable by one party to the other. The Company is neither required to pledge nor entitled to receive cash collateral related to these derivative transactions. Inventory Inventory consists primarily of component parts to be used in the manufacturing process and finished goods in-transit, and is stated at the lower of cost or net realizable value. In addition, the Company purchases and holds inventory to provide adequate component supplies over the life of the underlying products. Cost is computed using standard cost, which approximates actual cost, on a first-in, first-out basis. A charge is recorded to cost of product when inventory is determined to be in excess of anticipated demand or considered obsolete. At the point of loss recognition, a new, lower-cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in the restoration or increase in the newly established cost basis. Leases The Company determines if an arrangement is a lease at inception. The Company evaluates classification of leases as either operating or finance at commencement and, as necessary, at modification. As of December 31, 2019 , the Company did no t have any finance leases. Operating leases are included in operating lease right-of-use ("ROU") assets, other accrued liabilities, and operating lease liabilities on the Company's Consolidated Balance Sheets. ROU assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized on the commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the incremental borrowing rate on January 1, 2019 for operating leases that commenced prior to that date. The operating lease ROU asset also includes any lease payments made prior to lease commencement and excludes lease incentives. Variable lease payments not dependent on an index or a rate, are expensed as incurred and are not included within the ROU asset and lease liability calculation. Variable lease payments primarily include reimbursements of costs incurred by lessors for common area maintenance and utilities. The Company's lease terms are the noncancelable period, including any rent-free periods provided by the lessor, and include options to extend or terminate the lease when it is reasonably certain that it will exercise that option. At lease inception, and in subsequent periods as necessary, the Company estimates the lease term based on its assessment of extension and termination options that are reasonably certain to be exercised. Lease costs are recognized on a straight-line basis over the lease term. The Company does not separate non-lease components from lease components for all underlying classes of assets. In addition, the Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise. Lease cost for short-term leases is recognized on a straight-line basis over the lease term. Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 1.5 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 10 to 40 Leasehold improvements Lease term, not to exceed 10 years Land is not depreciated. Construction-in-process is related to the construction or development of property and equipment that have not yet been placed in service for their intended use. Business Combinations The purchase price of an acquired entity is allocated to tangible assets, liabilities, and intangible assets, including in-process research and development (IPR&D) based on their estimated fair values with the residual of the purchase price recorded as goodwill. The determination of the value of the intangible assets acquired involves certain estimates, such as expected future cash flows, which include consideration of future growth rates and margins, attrition rates, future changes in technology, discount rates, and the expected use of the acquired assets. These factors are also considered in determining the useful life of the acquired intangible assets. IPR&D is initially capitalized at fair value as an intangible asset with an indefinite life and assessed for impairment thereafter. When an IPR&D project is completed, the IPR&D is reclassed as an amortizable purchased intangible asset and amortized over the asset’s estimated useful life. Acquisition related expenses are recognized separately from business combination and are expensed as incurred. The Company's Consolidated Financial Statements include the operating results of acquired businesses from the date of each acquisition. Goodwill and Intangible Assets Goodwill is tested for impairment annually during the fourth quarter or more frequently if certain circumstances indicate the carrying value of goodwill is impaired. Goodwill is tested for impairment at the reporting unit level. A qualitative assessment is first performed to determine whether it is necessary to quantitatively test goodwill for impairment. This initial assessment includes, among others, consideration of macroeconomic conditions and financial performance. If the qualitative assessment indicates that it is more likely than not that an impairment exists, a quantitative analysis is performed by determining the fair value of each reporting unit using a combination of the discounted cash flow and the market approaches. Goodwill is considered impaired if the carrying value of the reporting unit exceeds its fair value. An impairment loss is recognized to the extent that the carrying amount of goodwill exceeds the asset's implied fair value. We conducted our annual impairment test of goodwill during the fourth quarters of 2019 and 2018 and determined that no adjustment to the carrying value of goodwill for any reporting units was required. Intangible assets consist of existing technology, customer relationships, and trade name, which are amortized over the period of estimated benefit using the straight-line method and estimated useful lives of 4 or 5 years. Other intangible assets acquired in a business combination related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. Indefinite-lived intangibles are not amortized into the results of operations but instead are evaluated for impairment. If and when development is complete, the associated assets would be deemed finite-lived and would be amortized as cost of revenues over their respective estimated useful lives at that point in time. If the research and development project is abandoned, the acquired IPR&D assets are written off and charged to expense in the period of abandonment. Impairment of Long-lived Assets Long-lived assets, such as property, plant, and equipment, ROU assets, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group, to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. An impairment charge is recognized by the amount by which the carrying amount of the asset, or asset group, exceeds its fair value. Warranty Reserves The Company generally offers a one -year warranty on most of its hardware products, and a 90 -day warranty on the media that contains the software embedded in the products. Warranty costs are recognized as part of the Company's cost of sales based on associated material costs, logistics costs, labor costs, and overhead at the time revenue is recognized. Material costs are estimated primarily based upon the historical costs to repair or replace product returns within the warranty period. Labor, logistics and overhead costs are estimated primarily based upon historical trends in the cost to support customer cases within the warranty period. Warranty reserve is reported within other accrued liabilities in the Consolidated Balance Sheets. Contract Manufacturer Liabilities The Company establishes a liability for non-cancelable, non-returnable purchase commitments with its contract manufacturers for carrying charges, quantities in excess of its demand forecasts, or obsolete material charges for components purchased by the contract manufacturers to meet the Company’s demand forecast or customer orders. The demand forecasts are based upon historical trends and analysis from the Company's sales and marketing organizations, adjusted for overall market conditions. Loss Contingencies The Company is subject to the possibility of various loss contingencies arising in the ordinary course of business. Management considers the likelihood of loss related to an asset, or the incurrence of a liability, as well as its ability to reasonably estimate the amount of loss, in determining loss contingencies. An estimated loss contingency is accrued when it is probable that an asset has been impaired or a liability has been incurred and the amount of loss can be reasonably estimated. The Company regularly evaluates current information available to determine whether such accruals should be adjusted and whether new accruals are required. Foreign Currency Assets and liabilities of foreign operations with non-U.S. Dollar functional currency are translated to U.S. Dollars using exchange rates in effect at the end of the period. Revenue and expenses are translated to U.S. Dollars using rates that approximate those in effect during the period. The resulting translation adjustments are included in the Company’s Consolidated Balance Sheets in the stockholders’ equity section as a component of accumulated other comprehensive loss. The Company remeasures monetary assets and monetary liabilities in non-functional currencies and records the resulting foreign exchange transaction gains and losses in other expense, net in the Consolidated Statements of Operations. Revenue Recognition Revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services by following a five-step process, (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price, and (5) recognize revenue when or as the Company satisfies a performance obligation, as further described below. Identify the contract with a customer . The Company generally considers a sales contract and/or agreement with an approved purchase order as a customer contract provided that collection is considered probable, which is assessed based on the creditworthiness of the customer as determined by credit checks, payment histories, and/or other circumstances. The Company combines contracts with a customer if contracts are negotiated with a single commercial substance or contain price dependencies. Identify the performance obligations in the contract . Product performance obligations include hardware and software licenses and service performance obligations include hardware maintenance, software post-contract support, training, and professional services. Certain software licenses and related post-contract support are combined into a single performance obligation when the maintenance updates are critical to the continued delivery of the software functionality. Determine the transaction price . The transaction price for the Company’s contracts with its customers consists of both fixed and variable consideration provided it is probable that a significant reversal of revenue will not occur when the uncertainty related to variable consideration is resolved. Fixed consideration includes amounts to be contractually billed to the customer while variable consideration includes estimates for rights of return, rebates, and price protection, which are based on historical sales returns and price protection credits, specific criteria outlined in rebate agreements, and other factors known at the time. The Company generally invoices customers for hardware, software licenses and related maintenance arrangements at time of delivery, and professional services either upfront or upon meeting certain milestones. Customer invoices are generally due within 30 to 90 days after issuance. The Company’s contracts with customers typically do not include significant financing components as the period between the transfer of performance obligations and timing of payment are generally within one year. Allocate the transaction price to the performance obligations in the contract . For contracts that contain multiple performance obligations, the Company allocates the transaction price to the performance obligations on a relative standalone selling price basis. Standalone selling prices are based on multiple factors including, but not limited to historical discounting trends for products and services, pricing practices in different geographies and through different sales channels, gross margin objectives, internal costs, competitor pricing strategies, and industry technology lifecycles. Recognize revenue when or as the Company satisfies a performance obligation . Revenue for hardware and certain software licenses, are recognized at a point in time, which is generally upon shipment or delivery. Certain software licenses combined with post-contract support are recognized over time on a ratable basis over the term of the license. Revenue for maintenance and software post-contract support is recognized over time on a ratable basis over the contract term. Revenue from training and professional services is recognized over time as services are completed or ratably over the contractual period of generally one year or less. Deferred product revenue represents unrecognized revenue related to undelivered product commitments and other shipments that have not met revenue recognition criteria. Deferred service revenue represents billed amounts for service contracts, which include technical support, hardware and software maintenance, professional services, and training, for which services have not been rendered. Revenue is recognized net of any taxes collected, which are subsequently remitted to governmental authorities. Deferred Commissions Sales commissions earned by the Company’s sales force are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are recorded as prepaid expenses or other longer assets and are deferred and then amortized over a period of benefit which is typically over the term of the customer contracts. Amortization expense is included in sales and marketing expenses in the accompanying Consolidated Statements of Operations. Research and Development Costs to research, design, and develop the Company's products are expensed as incurred. Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins when a product's technological feasibility has been established and ends when a product is available for general release to customers. Generally, the Company's products are released soon after technological feasibility has been established. As a result, costs incurred between achieving technological feasibility and product general availability have not been significant. The Company capitalizes costs associated with internal-use software systems during the application development stage. Such capitalized costs include external direct costs incurred in developing or obtaining the applications and payroll and payroll-related costs for employees, who are directly associated with the development of the applications. Advertising Advertising costs are charged to sales and marketing expense as incurred. Advertising expense was $14.6 million , $20.0 million , and $19.9 million , for 2019 , 2018 , and 2017 , respectively. Share-Based Compensation The Company measures and recognizes compensation cost for all share-based awards made to employees and directors, including employee stock options, restricted stock awards ("RSAs"), restricted stock units ("RSUs"), performance share awards ("PSAs") and employee stock purchases related to the Employee Stock Purchase Plan ("ESPP"). For service condition only awards, share-based compensation expense is based on the fair value of the underlying awards and amortized on a straight-line basis. For PSAs, share-based compensation expense is amortized on a straight-line basis for each separate vesting portion of the awards. The Company accounts for forfeitures as they occur. The Company utilizes the Black-Scholes-Merton (“BSM”) option-pricing model to estimate the fair value of its ESPP purchase rights. The BSM model requires various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, expected life, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected life of the Company’s ESPP. The expected life of ESPP purchase rights approximates the offering period. The Company determines the grant date fair value of its RSUs, RSAs, and PSAs based on the closing market price of the Company’s common stock on the date of grant, adjusted by the present value of the 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. For market-based RSUs, the Company estimates the fair value and derived service period using the Monte Carlo simulation option pricing model ("Monte Carlo model"). The determination of the grant date fair value and derived service periods using the Monte Carlo model is affected by the Company's stock price, comparative market-based returns, as well as various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors, including historical volatility of the Company’s common stock over the contractual life of the Company's market-based RSUs. Provision for Income Taxes Deferred tax assets and liabilities are recognized for the expected tax consequences of temporary differences between the tax basis of assets and liabilities and their reported amounts. Valuation allowances are recorded to reduce deferred tax assets to the amount that will more likely than not be realized. The Company accounts for uncertainty in income taxes using a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company classifies the liability for unrecognized tax benefits as current to the extent that the Company anticipates payment (or receipt) of cash within one year . Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes. The Company accounts for the current impacts of U.S. tax on certain foreign subsidiaries income, which is referred to as Global Intangible Low-Taxed Income in the year earned. Concentrations of Risk Financial instruments that subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, investments, derivatives, and accounts receivable. The Company invests only in high-quality credit instruments and maintains its cash, cash equivalents and available-for-sale investments in fixed income securities with several high-quality institutions. Deposits held with banks, including those held in foreign branches of global banks, may exceed the amount of insurance provided on such deposits. We mitigate the concentration of credit risk in our investment portfolio through diversification of the investments in various industries and asset classes, and limits to the amount of credit exposure to any single issuer and credit rating. The Company’s derivatives expose it to credit risk to the extent that counterparties may be unable to meet the terms of the agreement. To mitigate concentration of risk related to its derivatives, the Company establishes counterparty limits to major credit-worthy financial institutions. In addition, the potential risk of loss with any one counterparty resulting from this type of credit risk is monitored and the derivatives transacted with these entities are typically relatively short in duration. Therefore, the Company does not expect material losses as a result of defaults by counterparties. Generally, credit risk with respect to accounts receivable is diversified due to the number of entities comprising the Company's customer base and their dispersion across different geographic locations throughout the world. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. During the years ended December 31, 2019 , 2018 , and 2017 , no single customer accounted for 10% or more of net revenues. The Company relies on sole suppliers for certain of its components such as application-specific integrated circuits ("ASICs") and custom sheet metal. Additionally, the Company relies primarily on a limited number of significant independent contract manufacturers and original design manufacturers for the production of its products. The inability of any supplier or manufacturer to fulfill supply requirements of the Company could negatively impact future operating results.

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Business Combinations	Business Combinations The Company acquired Mist Systems, Inc. ("Mist") in 2019; HTBase Corporation ("HTBase") in 2018; and Cyphort Inc. ("Cyphort") in 2017. Pro forma results of operations for these acquisitions have not been presented as the financial impact to the Company's consolidated results of operations, both individually and in aggregate, is not material. The goodwill recognized for these acquisitions was primarily attributable to expected synergies and is not deductible for U.S. federal income tax purposes. 2019 Acquisition Mist On April 1, 2019, the Company acquired 100% ownership of Mist Systems, Inc. (“Mist”) for $359.2 million . The purchase consideration consisted of cash of $354.5 million and approximately $4.6 million in share-based awards attributable to services prior to the acquisition. The acquisition of Mist, a company that provides cloud-managed wireless networks powered by artificial intelligence, is expected to enhance Juniper's enterprise networking portfolio by combining Mist’s next-generation Wireless LAN platform with Juniper's wired LAN, SD-WAN, and security solutions to deliver integrated end-to-end user and IT experiences. Under the terms of the acquisition agreement with Mist, the Company assumed certain share-based awards for continuing employees, which were granted in contemplation of future services. The fair value of these share-based awards was $38.5 million , which will be expensed as share-based compensation over the remaining service period. 2018 Acquisition HTBase On December 7, 2018 , the Company acquired 100% of the equity of HTBase for $19.6 million of cash. The acquisition of HTBase, a software company that has developed a unique and disruptive platform for software-defined enterprise multicloud, is expected to accelerate Juniper's leadership in multicloud and function with the compute orchestration capabilities of Contrail Enterprise Multicloud. Prior to the acquisition, the Company had an outstanding promissory note and bridge notes totaling $1.6 million , measured at fair value, which were effectively settled upon acquisition. Under the terms of the acquisition agreement with HTBase, the Company granted certain share-based awards to continuing employees in substitution of awards held by such employees, which were granted in contemplation of future services. The fair value of these share-based awards was $3.8 million , which will be expensed as share-based compensation over the remaining service period. 2017 Acquisition Cyphort On September 18, 2017 , the Company acquired 100% of Cyphort for $33.5 million of cash. The acquisition of Cyphort, a software company providing security analytics for advanced threat defense, is expected to strengthen Juniper's security product portfolio. Under the terms of the acquisition agreement with Cyphort, the Company assumed certain share-based awards for continuing employees, which were granted in contemplation of future services. The fair value of these share-based awards was $3.8 million , which will be expensed as share-based compensation over the remaining service period. Acquisition Costs The Company recognized $16.6 million , $4.4 million , and $2.1 million of acquisition-related costs during the years ended December 31, 2019 , December 31, 2018 , and December 31, 2017 , respectively. These acquisition-related costs were expensed in the period incurred within general and administrative expense in the Company's Consolidated Statements of Operations. The following table summarizes the fair values of the assets acquired and liabilities assumed at the acquisition dates (in millions): 2019 2018 2017 Mist HTBase Cyphort Net tangible assets acquired/(liabilities) assumed $ 28.3 $ (1.0 ) $ 1.4 Intangible assets 102.0 7.8 15.4 Goodwill 228.9 14.4 16.7 Total $ 359.2 $ 21.2 $ 33.5 The following table summarizes the fair value of the separately identifiable intangible assets at the time of acquisition and the period over which each intangible asset will be amortized (in millions, except years): 2019 2018 2017 Mist HTBase Cyphort Weighted Amount Weighted Amount Weighted Amount Intangible assets: Existing technology 5 $ 81.0 4 $ 7.8 5 $ 15.4 Customer relationships 5 15.0 — — — — Trade name 5 6.0 — — — — Total intangible assets acquired $ 102.0 $ 7.8 $ 15.4

Cash Equivalents and Investment

Cash Equivalents and Investments	12 Months Ended
	Dec. 31, 2019
Cash Equivalents and Investments [Abstract]
Cash Equivalents and Investments	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 December 31, 2019 and December 31, 2018 (in millions): As of December 31, 2019 As of December 31, 2018 Amortized Gross Unrealized Gross Unrealized Estimated Fair Amortized Gross Unrealized Gross Unrealized Estimated Fair Fixed income securities: Asset-backed securities $ 81.3 $ 0.1 $ — $ 81.4 $ 46.8 $ — $ (0.3 ) $ 46.5 Certificates of deposit 38.6 — — 38.6 152.9 — — 152.9 Commercial paper 168.2 — — 168.2 393.6 — — 393.6 Corporate debt securities 604.9 0.7 (0.1 ) 605.5 416.1 — (3.1 ) 413.0 Foreign government debt securities 11.4 — — 11.4 20.0 — (0.1 ) 19.9 Time deposits 226.3 — — 226.3 278.6 — — 278.6 U.S. government agency securities 89.0 — — 89.0 87.2 — (0.2 ) 87.0 U.S. government securities 394.3 0.3 (0.1 ) 394.5 811.8 — (0.5 ) 811.3 Total fixed income securities 1,614.0 1.1 (0.2 ) 1,614.9 2,207.0 — (4.2 ) 2,202.8 Privately-held debt and redeemable preferred stock securities 19.1 37.4 — 56.5 16.6 37.4 — 54.0 Total available-for-sale debt securities $ 1,633.1 $ 38.5 $ (0.2 ) $ 1,671.4 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8 Reported as: Cash equivalents $ 290.9 $ — $ — $ 290.9 $ 936.5 $ — $ — $ 936.5 Short-term investments 733.7 0.5 — 734.2 1,069.2 — (1.9 ) 1,067.3 Long-term investments 589.4 0.6 (0.2 ) 589.8 201.3 — (2.3 ) 199.0 Other long-term assets 19.1 37.4 — 56.5 16.6 37.4 — 54.0 Total $ 1,633.1 $ 38.5 $ (0.2 ) $ 1,671.4 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8 The following table presents the contractual maturities of the Company's total fixed income securities as of December 31, 2019 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,024.6 $ 1,025.1 Due between one and five years 589.4 589.8 Total $ 1,614.0 $ 1,614.9 The following tables present the Company's total fixed income securities that were in an unrealized loss position as of December 31, 2019 and December 31, 2018 (in millions): 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 ) As of December 31, 2018 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 $ 3.1 $ — $ 43.0 $ (0.3 ) $ 46.1 $ (0.3 ) Corporate debt securities 72.6 (0.1 ) 330.7 (3.0 ) 403.3 (3.1 ) Foreign government debt securities 1.5 — 18.4 (0.1 ) 19.9 (0.1 ) U.S. government agency securities 2.0 — 45.2 (0.2 ) 47.2 (0.2 ) U.S. government securities 344.0 — 63.5 (0.5 ) 407.5 (0.5 ) Total fixed income securities $ 423.2 $ (0.1 ) $ 500.8 $ (4.1 ) $ 924.0 $ (4.2 ) 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. As of December 31, 2019 , the Company had 179 investments in unrealized loss positions. The gross unrealized losses related to these investments were primarily due to changes in market interest rates. The Company does not intend to sell these investments and does not believe that it is more likely than not it will be required to sell any of these investments before recovery of the entire amortized cost basis, therefore the Company has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the years ended December 31, 2019 , 2018 , and 2017 . During the years ended December 31, 2019 , 2018 , and 2017 , 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 December 31, 2019 and 2018 (in millions): As of December 31, 2019 2018 Equity investments with readily determinable fair value Money market funds $ 446.4 $ 996.9 Mutual funds 26.8 24.3 Publicly-traded equity securities 3.8 2.8 Equity investments without readily determinable fair value 133.3 36.4 Total equity securities $ 610.3 $ 1,060.4 Reported as: Cash equivalents $ 442.3 $ 985.3 Short-term investments 3.8 2.8 Prepaid expenses and other current assets 4.1 10.9 Other long-term assets 160.1 61.4 Total $ 610.3 $ 1,060.4 In October 2019, the Company invested $89.9 million for a 13.7% equity ownership of a privately-held company. The investment was accounted for under the measurement alternative approach, at cost. The investment was classified in other long-term assets on the Consolidated Balance Sheets. During the years ended December 31, 2019 , 2018 , and 2017 , 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 NQDC plan for senior-level employees. Restricted investments are designated as equity investments. As of December 31, 2019 , the carrying value of restricted cash and investments was $91.6 million , of which $64.6 million was included in prepaid expenses and other current assets and $27.0 million was included in other long-term assets on the Consolidated Balance Sheets. The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Consolidated Balance Sheets as of December 31, 2019 and December 31, 2018 (in millions): As of December 31, 2019 2018 Cash and cash equivalents $ 1,215.8 $ 2,489.0 Restricted cash included in Prepaid expenses and other current assets 60.7 16.8 Total cash, cash equivalents, and restricted cash $ 1,276.5 $ 2,505.8

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 Consolidated Balance Sheets (in millions): Fair Value Measurements at Fair Value Measurements at Quoted Prices in Significant Other Significant Other Total Quoted Prices in Significant Other Significant Other Total Assets: Available-for-sale debt securities: Asset-backed securities $ — $ 81.4 $ — $ 81.4 $ — $ 46.5 $ — $ 46.5 Certificates of deposit — 38.6 — 38.6 — 152.9 — 152.9 Commercial paper — 168.2 — 168.2 — 393.6 — 393.6 Corporate debt securities — 605.5 — 605.5 — 413.0 — 413.0 Foreign government debt securities — 11.4 — 11.4 — 19.9 — 19.9 Time deposits — 226.3 — 226.3 — 278.6 — 278.6 U.S. government agency securities — 89.0 — 89.0 — 87.0 — 87.0 U.S. government securities 318.9 75.6 — 394.5 352.8 458.5 — 811.3 Privately-held debt and redeemable preferred stock securities — — 56.5 56.5 — — 54.0 54.0 Total available-for-sale debt securities 318.9 1,296.0 56.5 1,671.4 352.8 1,850.0 54.0 2,256.8 Equity securities: Money market funds 446.4 — — 446.4 996.9 — — 996.9 Mutual funds 26.8 — — 26.8 24.3 — — 24.3 Publicly-traded equity securities 3.8 — — 3.8 2.8 — — 2.8 Total equity securities 477.0 — — 477.0 1,024.0 — — 1,024.0 Derivative assets: Foreign exchange contracts — 2.5 — 2.5 — 5.3 — 5.3 Total derivative assets — 2.5 — 2.5 — 5.3 — 5.3 Total assets measured at fair value on a recurring basis $ 795.9 $ 1,298.5 $ 56.5 $ 2,150.9 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Liabilities: Derivative liabilities: Foreign exchange contracts $ — $ (6.8 ) $ — $ (6.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Interest rate swap contracts — (3.1 ) — (3.1 ) — — — — Total derivative liabilities — (9.9 ) — (9.9 ) — (7.1 ) — (7.1 ) Total liabilities measured at fair value on a recurring basis $ — $ (9.9 ) $ — $ (9.9 ) $ — $ (7.1 ) $ — $ (7.1 ) Total assets, reported as: Cash equivalents $ 442.3 $ 290.9 $ — $ 733.2 $ 1,025.2 $ 896.6 $ — $ 1,921.8 Short-term investments 188.8 549.2 — 738.0 297.5 772.6 — 1,070.1 Long-term investments 133.9 455.9 — 589.8 18.2 180.8 — 199.0 Prepaid expenses and other current assets 4.1 2.5 — 6.6 10.8 5.3 — 16.1 Other long-term assets 26.8 — 56.5 83.3 25.1 — 54.0 79.1 Total assets measured at fair value on a recurring basis $ 795.9 $ 1,298.5 $ 56.5 $ 2,150.9 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Fair Value Measurements at Fair Value Measurements at Quoted Prices in Significant Other Significant Other Total Quoted Prices in Significant Other Significant Other Total Total liabilities, reported as: Other accrued liabilities $ — $ (6.8 ) $ — $ (6.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Other long-term liabilities — (3.1 ) — (3.1 ) — — — — Total liabilities measured at fair value on a recurring basis $ — $ (9.9 ) $ — $ (9.9 ) $ — $ (7.1 ) $ — $ (7.1 ) 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. The Company's policy is to recognize asset or liability transfers among Level 1, Level 2, and Level 3 at the beginning of the quarter in which a change in circumstances resulted in a transfer. During the years ended December 31, 2019 and 2018 , the Company had no transfers between levels 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 financing activities and the investee's capital structure. During the year ended December 31, 2019 , there were no material activities related to privately-held debt and redeemable preferred stock. 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 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 December 31, 2019, there have been no upward or material 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, when they are deemed to be other-than temporarily impaired. There were no impairment charges recognized during the years ended December 31, 2019 , 2018 , and 2017 . As of December 31, 2019 and 2018 , the Company had no liabilities 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 December 31, 2019 and December 31, 2018 , the estimated fair value of the Company's total outstanding debt in the Consolidated Balance Sheets was $1,852.1 million and $2,158.7 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 ("the Pulse Note"), along with the accumulated interest paid in kind, of $78.9 million and $69.0 million approximates its fair value as of December 31, 2019 and December 31, 2018 , respectively. Notes receivable are generally classified as Level 3 asset due to the lack of observable inputs to determine fair value. The carrying value of a contract manufacturer deposit of $46.0 million , reported within other long-term assets in the Consolidated Balance Sheets approximates its fair value as of December 31, 2019 . See Note 8, Other Financial Information, for further information on the Pulse Note and contract manufacturer deposit.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The notional amount of the Company's derivative instruments is summarized as follows (in millions): As of December 31, 2019 2018 Designated derivatives: Cash flow hedges $ 484.0 $ 497.7 Interest rate swap contracts 300.0 — Total designated derivatives $ 784.0 $ 497.7 Non-designated derivatives 162.9 158.7 Total $ 946.9 $ 656.4 The fair value of derivative instruments on the Consolidated Balance Sheets was as follows: As of December 31, Balance Sheet Location 2019 2018 Derivative assets: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other current assets $ 2.2 $ 5.2 Foreign currency contracts as cash flow hedges Other long-term assets 0.3 — Total derivatives designated as hedging instruments $ 2.5 $ 5.2 Derivatives not designated as hedging instruments Other current assets — 0.1 Total derivative assets $ 2.5 $ 5.3 Derivative liabilities: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other accrued liabilities $ 6.6 $ 6.6 Interest rate swap designated as fair value hedges Other long-term liabilities 3.1 — Total derivatives designated as hedging instruments $ 9.7 $ 6.6 Derivatives not designated as hedging instruments Other accrued liabilities 0.2 0.5 Total derivative liabilities $ 9.9 $ 7.1 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. Cash flow hedge derivatives typically have maturities of twenty-four months or less. As of December 31, 2019 , an estimated $4.4 million of unrealized net loss within accumulated other comprehensive loss is expected to be reclassified into earnings within the next twelve 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 London InterBank Offered Rate (LIBOR). All of the interest rate swaps will expire within ten years or less . Effect of Derivative Instruments on the Consolidated Statements of Operations For foreign currency forward contracts, the Company recognized unrealized losses of $6.3 million and $8.7 million , and an unrealized gain of $20.2 million in accumulated other comprehensive loss for the effective portion of its derivative instruments during the years ended December 31, 2019 , 2018 , and 2017 , respectively. The Company reclassified a loss of $3.8 million and gains of $0.9 million and $7.6 million out of accumulated other comprehensive loss to cost of revenues and operating expenses in the Consolidated Statement of Operations during the years ended December 31, 2019 , 2018 , and 2017 , respectively. 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 recorded in other expense, net within the Consolidated Statements of Operations were $3.6 million , $7.6 million and $1.8 million during the years ended December 31, 2019 , 2018 , and 2017 , respectively. See Note 2, Significant Accounting Policies, for the Company’s policy regarding the offsetting of derivative assets and derivative liabilities.

Goodwill and Purchased Intangib

Goodwill and Purchased Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Purchased Intangible Assets	Goodwill and Purchased Intangible Assets Goodwill The Company's goodwill activity was as follows (in millions): Total December 31, 2017 $ 3,096.2 Additions due to business combination 14.4 Other (*) (1.8 ) December 31, 2018 3,108.8 Additions due to business combination 228.3 December 31, 2019 $ 3,337.1 ________________________________ (*) Other primarily consists of certain purchase accounting adjustments related to the acquisition of Cyphort. In the fourth quarter of 2019, the Company performed its annual goodwill impairment test for the three reporting units: Routing, Switching, and Security. There was no goodwill impairment during the years ended December 31, 2019 , 2018 , and 2017 . Purchased Intangible Assets The Company’s purchased intangible assets, net, were as follows (in millions): As of December 31, 2019 As of December 31, 2018 Gross Accumulated Accumulated Impairments and Net Gross Accumulated Accumulated Impairments and Net Finite-lived intangible assets: Technologies and patents $ 729.1 $ (564.0 ) $ (49.9 ) $ 115.2 $ 648.1 $ (534.0 ) $ (49.9 ) $ 64.2 Customer contracts, support agreements, and related relationships 98.6 (79.3 ) (2.8 ) 16.5 83.6 (75.5 ) (2.8 ) 5.3 Trade names and other 7.9 (2.8 ) — 5.1 2.0 (2.0 ) — — Total 835.6 (646.1 ) (52.7 ) 136.8 733.7 (611.5 ) (52.7 ) 69.5 Indefinite-lived intangible assets: IPR&D 49.0 — — 49.0 49.0 — — 49.0 Total purchased intangible assets $ 884.6 $ (646.1 ) $ (52.7 ) $ 185.8 $ 782.7 $ (611.5 ) $ (52.7 ) $ 118.5 Amortization expense related to purchased intangible assets with finite lives was $34.7 million , $17.4 million , and $17.5 million for the years ended December 31, 2019 , 2018 , and 2017 , respectively. There were no impairment charges related to purchased intangible assets during the years ended December 31, 2019 , 2018 , and 2017 . As of December 31, 2019 , the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions): Years Ending December 31, Amount 2020 $ 39.5 2021 35.3 2022 30.0 2023 25.7 2024 6.3 Thereafter — Total $ 136.8

Other Financial Information

Other Financial Information	12 Months Ended
	Dec. 31, 2019
Other Financial Information [Abstract]
Other Financial Information	Other Financial Information Inventory Total inventory consisted of the following (in millions): As of December 31, 2019 2018 Production and service materials $ 69.0 $ 60.6 Finished goods 25.2 21.4 Inventory $ 94.2 $ 82.0 Reported as: Prepaid expenses and other current assets $ 90.6 $ 80.6 Other long-term assets 3.6 1.4 Total $ 94.2 $ 82.0 Property and Equipment, Net Property and equipment, net, consisted of the following (in millions): As of December 31, 2019 2018 Computers and equipment $ 1,041.4 $ 1,100.0 Software 228.6 223.3 Leasehold improvements 216.9 235.2 Furniture and fixtures 48.3 48.6 Building and building improvements 255.0 254.3 Land and land improvements 243.5 243.2 Construction-in-process 12.9 19.5 Property and equipment, gross 2,046.6 2,124.1 Accumulated depreciation (1,215.7 ) (1,172.4 ) Property and equipment, net $ 830.9 $ 951.7 Depreciation expense was $184.0 million , $193.2 million , and $202.8 million in 2019 , 2018 , and 2017 , respectively. Notes Receivable and Deposit Total outstanding notes receivable and deposit, net of issuance costs, reported within other long-term assets in the Consolidated Balance Sheets were as follows (in millions): As of December 31, 2019 2018 Pulse Note (including accumulated interest paid in kind) $ 78.9 $ 69.0 Contract manufacturer deposit (non-interest bearing) 46.0 23.9 Total $ 124.9 $ 92.9 In connection with the sale of its Junos Pulse product portfolio in 2014, the Company was issued a non-contingent interest-bearing promissory note of $125.0 million . In 2017, the Company received payment of $75.0 million and the outstanding interest due. The maturity date of the Pulse Note was extended to September 30, 2022 under the terms of an amended agreement. The amended agreement also provided that interest due on the note be paid in kind by increasing the principal amount and interest rate on the Pulse Note. The outstanding balance of the Pulse Note was classified as a long-term asset based on expected collection beyond twelve months from the Consolidated Balance Sheet date. In 2018, the Company paid a deposit of $25.0 million to a contract manufacturer in exchange for improved pricing and savings on inventory carrying charges. The deposit was recorded at the face value of $25.0 million , less an unamortized discount of $1.1 million , calculated based on an imputed interest rate of 4.8% , that will be amortized over the term of the deposit to interest income along with a corresponding amount to cost of revenues. In 2019, the Company paid an additional non-interest bearing deposit of $23.6 million , for a total balance of $48.6 million , less an unamortized discount of $2.6 million , calculated based on an imputed interest rate of 5.0% as of December 31, 2019 . The deposit is due on demand in the first quarter of 2021 and was classified as other long-term assets on the Consolidated Balance Sheets. Interest income on the notes receivable is accrued and credited to interest income as it is earned, unless it is not probable the Company will collect the amounts due or if the present value of expected cash flows is less than the recorded investment. Interest income recognized was $10.4 million , $8.4 million , and $8.3 million , during the years ended December 31, 2019 , 2018 , and 2017 , respectively. The Company considers notes receivable to be impaired when, based on current information and events, it is probable that the Company will not be able to collect the scheduled payments of principal or interest when due. No impairment charge was required as of December 31, 2019 , 2018 , and 2017 . Warranties Changes in the Company’s warranty reserve were as follows (in millions): As of December 31, 2019 2018 Beginning balance $ 28.0 $ 27.4 Provisions made during the period, net 39.0 30.7 Actual costs incurred during the period (35.6 ) (30.1 ) Ending balance $ 31.4 $ 28.0 Deferred Revenue Details of the Company's deferred revenue, as reported in the Consolidated Balance Sheets, were as follows (in millions): As of December 31, 2019 2018 Deferred revenue: Undelivered product commitments and other product deferrals $ 141.7 $ 163.3 Deferred gross product revenue 141.7 163.3 Deferred cost of product revenue (9.1 ) (18.9 ) Deferred product revenue, net 132.6 144.4 Deferred gross service revenue 1,090.8 1,071.8 Deferred cost of service revenue — (2.6 ) Deferred service revenue, net 1,090.8 1,069.2 Total $ 1,223.4 $ 1,213.6 Reported as: Current $ 812.9 $ 829.3 Long-term 410.5 384.3 Total $ 1,223.4 $ 1,213.6 Revenue See Note 13, Segments, for disaggregated revenue by product and service, customer vertical, and geographic region. Product revenue of $68.6 million included in deferred revenue at January 1, 2019 was recognized during the year ended December 31, 2019 . Service revenue of $706.8 million included in deferred revenue at January 1, 2019 was recognized during the year ended December 31, 2019 . The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of December 31, 2019 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 $ 141.7 $ 118.6 $ 19.9 $ 3.2 Service (*) 1,103.6 706.7 328.3 68.6 Total $ 1,245.3 $ 825.3 $ 348.2 $ 71.8 ________________________________ (*) Represents unearned service revenue allocated to the performance obligations not delivered or partially delivered as of December 31, 2019. The unearned service revenue are comprised of deferred revenue and unbilled revenue. Deferred Commissions Deferred commissions were $24.1 million and $33.7 million as of December 31, 2019 and 2018 , respectively. During the years ended December 31, 2019 and 2018 , amortization expense for the deferred commissions were $130.9 million and $144.2 million , respectively, and there were no impairment charges recognized. Other Expense, Net Other expense, net consisted of the following (in millions): Years Ended December 31, 2019 2018 2017 Interest income $ 79.1 $ 72.7 $ 53.0 Interest expense (88.7 ) (103.2 ) (101.2 ) Loss on extinguishment of debt (15.3 ) — — (Loss) gain on investments, net (3.8 ) (7.4 ) 14.6 Other 0.9 (1.6 ) (2.7 ) Other expense, net $ (27.8 ) $ (39.5 ) $ (36.3 ) Interest income primarily includes interest earned on the Company’s cash, cash equivalents, investments, and promissory note issued to the Company in connection with the sale of Junos Pulse. Interest expense primarily includes interest, net of capitalized interest expense, from long-term debt and customer financing arrangements. Loss on extinguishment of debt resulted from the early repayment of senior notes due 2020 and 2021. (Loss) gain on investments, net, primarily includes (Loss) gains from the sale of investments in public and privately-held companies, and any observable changes in fair value and impairment charges recorded on these investments. Other typically consists of foreign exchange gains and losses and other non-operational income and expense items.

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2019
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges The following table presents restructuring charges included in the Consolidated Statements of Operations (in millions): Years Ended December 31, 2019 2018 2017 Severance $ 21.5 $ 8.3 $ 57.7 Facility consolidations 2.1 — — Contract terminations 11.7 (1.0 ) 7.9 Total $ 35.3 $ 7.3 $ 65.6 Reported as: Restructuring charges $ 35.3 $ 7.3 $ 65.6 Total $ 35.3 $ 7.3 $ 65.6 2019 Restructuring Plan In 2019, the Company initiated a restructuring plan (the "2019 Restructuring Plan") designed to realign its workforce with the Company's sales strategy, improve productivity, and enhance cost efficiencies, which resulted in severance, facility consolidation, and contract termination costs that were recorded to restructuring charges in the Consolidated Statement of Operations. The 2019 Restructuring Plan was substantially completed as of December 31, 2019. Prior Restructuring Activities In 2018, the Company initiated a restructuring plan (the "2018 Restructuring Plan") to realign its workforce as a result of organizational and leadership changes. The 2018 Restructuring Plan consisted of severance and contract termination costs that were recorded to restructuring charges in the Consolidated Statement of Operations. In 2017, the Company initiated a restructuring plan (the “2017 Restructuring Plan”) to realign its workforce and increase operational efficiencies. The 2017 Restructuring Plan consisted of severance and contract termination costs that were recorded to restructuring charges in the Consolidated Statement of Operations. Restructuring Liabilities Restructuring liabilities are reported within other accrued liabilities in the Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liabilities associated with the 2019 Restructuring Plan and prior year plans (in millions): December 31, Charges/ (Benefits) Cash December 31, Severance $ 1.1 $ 21.5 $ (21.9 ) $ — $ 0.7 Facility consolidations — 2.1 (0.1 ) (2.0 ) — Contract terminations — 11.7 (11.5 ) (0.2 ) — Total $ 1.1 $ 35.3 $ (33.5 ) $ (2.2 ) $ 0.7

Debt and Financing

Debt and Financing	12 Months Ended
	Dec. 31, 2019
Debt Instruments [Abstract]
Debt and Financing	Debt and Financing Debt The following table summarizes the Company's total debt (in millions, except percentages): As of December 31, 2019 Issuance date Maturity Date Amount Effective Interest Rates Senior Notes ("Notes"): 4.500% fixed-rate notes (1) ("2024 Notes") March 2014 March 2024 $ 350.0 4.63 % 4.500% fixed-rate notes (1) ("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 (13.0 ) Hedge accounting fair value adjustments (2) (3.1 ) Total $ 1,683.9 ________________________________ (1) 2024 Notes issued in March 2014 and February 2016 form a single series and are fully fungible. (2) 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 6 , 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. As of December 31, 2019 , the Company's aggregate debt maturities based on outstanding principal were as follows (in millions): Years Ending December 31, Amount 2020 $ — 2021 — 2022 — 2023 — 2024 500.0 Thereafter 1,200.0 Total $ 1,700.0 In August 2019, the Company issued $500.0 million aggregate principal amount of 3.75% senior notes due 2029 . The net proceeds from the issuance of the 2029 Notes, together with cash on hand, were used for the repayment of $600.0 million aggregate principal amount of the Company's 3.30% senior notes due 2020 and 4.60% senior notes due 2021 . The repayments were made in August and September 2019. The repayments resulted in a loss on extinguishment of debt of $15.3 million , which was recorded under other expense, net within the Consolidated Statements of Operations. The Company may redeem the 2025 Notes and the 2029 Notes, either in whole or in part, at any time three months prior to the maturity date of the 2025 Notes, and three months prior to the maturity date of the 2029 Notes, respectively, at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the 2025 Notes and the 2029 Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted at the Treasury rate plus 37.5 basis points for the 2025 Notes, or the Treasury rate plus 35.0 basis points for the 2029 Notes, plus, in the case of each of the clauses (i) and (ii) above, accrued and unpaid interest, if any. At any time on or after March 15, 2025, in the case of the 2025 Notes, and at any time on or after March 15, 2029, in the case of the 2029 Notes, the Company may redeem Notes of such series, in whole or in part, at a redemption price equal to 100% of the principal amount of the 2025 Notes and the 2029 Notes to be redeemed, plus accrued and unpaid interest, if any. The Company may redeem the other Notes, either in whole or in part, at any time at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted to the redemption date, plus, in either case, accrued and unpaid interest, if any. In the event of a change of control repurchase event, the holders of the Notes may require the Company to repurchase for cash all or part of the Notes at a purchase price equal to 101% of the aggregate principal amount, plus accrued and unpaid interest, if any. 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 December 31, 2019 , the Company was in compliance with all covenants in the indentures governing the Notes. Revolving Credit Facility In April 2019, the Company entered into a new credit agreement (the "Credit Agreement") with certain institutional lenders that provides for a five -year $500.0 million unsecured revolving credit facility (the "Revolving Credit Facility"), with an option to increase the Revolving Credit Facility by up to an additional $200.0 million , subject to the lenders' approval. Proceeds of loans made under the Revolving Credit Facility may be used by the Company for working capital and general corporate purposes. The Revolving Credit Facility will terminate in April 2024, subject to two one -year maturity extension options, on the terms and conditions as set forth in the credit agreement. As of December 31, 2019 , there were no amounts outstanding under the Revolving Credit Facility. Borrowings under the Revolving Credit Facility will bear interest, at either (i) a floating rate per annum equal to the base rate plus a margin of between 0.00% and 0.375% , depending on the Company's public debt rating or (ii) a per annum rate equal to the reserve adjusted Eurocurrency rate, plus a margin of between 0.910% and 1.375% , depending on the Company's public debt rating. Base rate is defined as the greatest of (A) Citibank's base rate, (B) the federal funds rate plus 0.500% or (C) the ICE Benchmark Administration Settlement Rate applicable to dollars for a period of one month plus 1.00% . The Eurocurrency rate is determined for U.S. dollars and Pounds Sterling as the rate at which deposits in such currency are offered in the London interbank market for the applicable interest period and for Euro as the rate specified for deposits in Euro with a maturity comparable to the applicable interest period. The Revolving Credit Facility requires the Company to maintain a leverage ratio no greater than 3.0 x (provided that if a material acquisition has been consummated, the Company is permitted to maintain a leverage ratio no greater than 3.5 x for up to four quarters) and an interest coverage ratio no less than 3.0 x during the term of the credit facility. As of December 31, 2019 , the Company had no t borrowed any funds under the Credit Agreement and was in compliance with all covenants in the Credit Agreement. Financing Arrangements The Company provides certain customers with access to extended financing arrangements that allow for longer payment terms than those typically provided by the Company by factoring accounts receivable to third-party financing providers ("financing providers"). The program does not and is not intended to affect the timing of the Company's revenue recognition. Under the financing arrangements, proceeds from the financing providers are due to the Company within 1 to 90 days from the sale of the receivable. In these transactions with the financing providers, the Company surrenders control over the transferred assets. Pursuant to the financing arrangements for the sale of receivables, the Company sold receivables of $64.0 million , $122.8 million and $169.4 million during the years ended December 31, 2019 , 2018 , and 2017 , respectively. The Company received cash proceeds from financing providers of $69.7 million , $123.2 million , and $169.3 million during the years ended December 31, 2019 , 2018 , and 2017 , respectively. As of December 31, 2019 and December 31, 2018 , the amounts owed by the financing providers were $5.3 million and $17.2 million , respectively, which were recorded in accounts receivable on the Company’s Consolidated Balance Sheets.

Equity

Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Equity	Equity The following table summarizes dividends paid, stock repurchases and retirements under the Company's stock repurchase programs, and stock repurchases for tax withholdings (in millions, except per share amounts): Dividends Stock Repurchases Total Year Per Share Amount Shares Average price (1) Amount (2) Tax Withholding Amount Amount 2019 $ 0.76 $ 260.1 20.1 $ 25.36 $ 550.0 $ 5.0 $ 815.1 2018 $ 0.72 $ 249.3 29.3 $ 25.62 $ 750.0 $ 6.6 $ 1,005.9 2017 $ 0.40 $ 150.4 26.1 $ 27.61 $ 719.7 $ 6.1 $ 876.2 ________________________________ (1) $25.36 average price per share for 2019 excludes the $40.0 million covered by the forward contract discussed below. (2) 2019 and 2018 shares were repurchased under the 2018 Stock Repurchase Program. 2017 shares were repurchased under the 2014 Stock Repurchase Program. Cash Dividends on Shares of Common Stock During 2019 , the Company declared four quarterly cash dividends of $0.19 per share on its common stock on January 29, 2019, April 25, 2019, July 25, 2019 and October 24, 2019, respectively, which were paid on March 22, 2019, June 24, 2019, September 25, 2019 and December 23, 2019, respectively, to stockholders of record as of the close of business on March 1, 2019, June 3, 2019, September 4, 2019, and December 2, 2019, respectively. 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 18, Subsequent Events, for discussion of the Company's dividend declaration subsequent to December 31, 2019 . Stock Repurchase Activities In January 2018, the Board approved a $2.0 billion share repurchase program ("2018 Stock Repurchase Program"). In October 2019, the Board authorized a $1.0 billion increase to the 2018 Stock Repurchase Program for a total of $3.0 billion . The 2018 Stock Repurchase Program replaces the previous authorization approved by the Board in 2014 ("2014 Stock Repurchase Program"). As part of the 2018 Stock Repurchase Program, in February 2018 and April 2019, the Company entered into two accelerated share repurchase programs ("ASR") and repurchased $750.0 million and $300.0 million of the Company's common stock, respectively. The aggregate number of shares ultimately repurchased of 29.3 million and 11.6 million shares of the Company's common stock was determined based on a volume weighted average repurchase price, less an agreed upon discount, of $25.62 and $25.79 per share, respectively. The shares received by the Company were retired, accounted for as a reduction to stockholder’s equity in the Consolidated Balance Sheets, and treated as a repurchase of common stock for purposes of calculating earnings per share. As part of the 2018 Stock Repurchase Program, in October 2019, the Company entered into an ASR with a financial institution to repurchase an aggregate of $200.0 million of the Company's outstanding common stock. 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. The initial shares received by the Company were retired, accounted for as a reduction to stockholder’s equity in the Consolidated Balance Sheets, and treated as a repurchase of common stock for purposes of calculating earnings per share. The forward contract for the remaining $40.0 million is considered indexed to the Company's common stock and met all of the applicable criteria for equity classification. See Note 18, Subsequent Events, for a discussion of the Company's ASR completion subsequent to December 31, 2019 . During the fiscal year ended December 31, 2019 , the Company also repurchased 2.1 million shares of its common stock in the open market for an aggregate purchase price of $50.0 million at an average price of $23.63 per share, under the 2018 Stock Repurchase Program. As of December 31, 2019 , there were $1.7 billion of authorized funds remaining under the 2018 Stock Repurchase Program. See Note 18, Subsequent Events, for a discussion of the Company's stock repurchase activity subsequent to December 31, 2019. 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. Accumulated Other Comprehensive Loss, Net of Tax The components of accumulated other comprehensive loss, net of related taxes, for the years ended December 31, 2019 , 2018 , and 2017 were as follows (in millions): Unrealized Gains/Losses on Available-for- Sale Debt Securities (1) Unrealized Gains/Losses on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2016 $ 16.6 $ (4.5 ) $ (49.4 ) $ (37.3 ) Other comprehensive income before reclassifications 4.5 15.7 19.0 39.2 Amount reclassified from accumulated other comprehensive loss (2.1 ) (5.2 ) — (7.3 ) Other comprehensive income, net 2.4 10.5 19.0 31.9 Balance as of December 31, 2017 $ 19.0 $ 6.0 $ (30.4 ) $ (5.4 ) Other comprehensive income (loss) before reclassifications 0.6 (6.4 ) (12.4 ) (18.2 ) Amount reclassified from accumulated other comprehensive income (loss) 0.9 (1.2 ) — (0.3 ) Other comprehensive income (loss), net 1.5 (7.6 ) (12.4 ) (18.5 ) Reclassification of tax effects upon adoption of ASU 2018-02 5.0 0.7 — 5.7 Balance as of December 31, 2018 $ 25.5 $ (0.9 ) $ (42.8 ) $ (18.2 ) Other comprehensive income (loss) before reclassifications 4.6 (8.9 ) (1.1 ) (5.4 ) Amount reclassified from accumulated other comprehensive income (loss) (0.4 ) 5.5 — 5.1 Other comprehensive income (loss), net 4.2 (3.4 ) (1.1 ) (0.3 ) Balance as of December 31, 2019 $ 29.7 $ (4.3 ) $ (43.9 ) $ (18.5 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive loss during the years ended December 31, 2019 , 2018 , and 2017 for realized gains on available-for-sale debt securities were not material, and were included in other expense, net, in the Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive loss during the years ended December 31, 2019 , 2018 , and 2017 for realized gains and losses on cash flow hedges were not material, and were included within cost of revenues, research and development, sales and marketing, and general and administrative in the Consolidated Statements of Operations.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Employee Benefit Plans	Employee Benefit Plans Equity Incentive Plans The Company’s equity incentive plans include the 2015 Equity Incentive Plan (the “2015 Plan”), the 2006 Equity Incentive Plan (the “2006 Plan”), and the 2008 Employee Stock Purchase Plan (the “ESPP”). Under these plans, the Company has granted stock options, RSUs, and PSAs. In addition, in connection with certain past acquisitions, the Company has assumed or substituted stock options, RSUs, RSAs, and PSAs granted under the stock plans of the acquired companies. Such awards were converted into or replaced with the Company's stock options, RSUs, RSAs, and PSAs, respectively. The 2015 Plan was adopted and approved by the Company's stockholders in May 2015 and had an initial authorized share reserve of 38.0 million shares of common stock, plus the addition of any shares subject to outstanding awards under the 2006 Plan and the Amended and Restated 1996 Stock Plan that were outstanding as of May 19, 2015, and that subsequently expire or otherwise terminate, up to a maximum of an additional 29.0 million shares. In May 2017, the Company's stockholders approved an additional 23.0 million shares of common stock for issuance under the 2015 Plan, and in May 2019, the Company's stockholders approved an additional 3.7 million shares of common stock for issuance under the 2015 Plan. As of December 31, 2019 , an aggregate of 13.7 million shares were subject to outstanding equity awards under the 2015 Plan and the 2006 Plan. As of December 31, 2019 , 16.6 million shares were available for future issuance under the 2015 Plan and no shares were available for future issuance under the 2006 Plan or the 1996 Plan. The ESPP was adopted and approved by the Company's stockholders in May 2008. To date, the Company's stockholders have approved a share reserve of 35.0 million shares of the Company's common stock for issuance under the ESPP. The ESPP permits eligible employees to acquire shares of the Company’s common stock at a 15% discount (as determined in the ESPP) through periodic payroll deductions of up to 10% of base compensation, subject to individual purchase limits of 6,000 shares in any twelve -month period or $25,000 worth of stock, determined at the fair market value of the shares at the time the stock purchase option is granted, in one calendar year. The ESPP provides 24 month offering periods with four 6 -month purchase periods. A new 24-month offering period will commence every six months thereafter. 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. As of December 31, 2019 , approximately 28.7 million shares have been issued and 6.3 million shares remain available for future issuance under the ESPP. During 2019, 2018, and 2017, the Company completed the acquisitions of Mist, HTBase, and Cyphort. In connection with these acquisitions, the Company assumed or substituted an aggregate of 2.2 million shares of stock options, RSUs, RSAs, and PSAs. No additional awards can be granted under the stock plans of the acquired companies. As of December 31, 2019 , approximately 3.8 million shares of common stock were outstanding under all awards assumed or substituted through the Company's acquisitions. RSU, RSA, and PSA Activities RSUs and RSAs generally vest over three years from the date of grant, and PSAs generally vest over a period of two to three years provided that certain annual performance targets and other vesting criteria are met. Until vested, RSUs and PSAs do not have the voting and dividend participation rights of common stock and the shares underlying the awards are not considered issued and outstanding. The following table summarizes the Company’s RSU, RSA, and PSA activity and related information as of and for the year ended December 31, 2019 (in millions, except per share amounts and years): Outstanding RSUs, RSAs, and PSAs (4) Number of Shares Weighted Average Grant-Date Fair Value per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance at December 31, 2018 17.4 $ 25.32 RSUs granted (1) 7.6 25.06 RSUs assumed upon the acquisition of Mist (1) 0.1 25.81 RSAs assumed upon the acquisition of Mist (1) 0.7 27.20 PSAs granted (2) 2.1 25.30 RSUs vested (3) (5.5 ) 25.99 RSAs vested (3) (0.2 ) 25.32 PSAs vested (3) (0.9 ) 25.13 RSUs canceled (2.3 ) 25.97 RSAs canceled (0.1 ) 27.65 PSAs canceled (1.4 ) 21.53 Balance at December 31, 2019 17.5 $ 25.30 1.1 $ 430.9 As of December 31, 2019 Vested and expected-to-vest RSUs, RSAs, and PSAs 16.2 $ 25.32 1.1 $ 399.2 ________________________________ (1) The weighted-average grant-date fair value of RSUs, RSAs, and PSAs granted and assumed or substituted during 2019 , 2018 , and 2017 was $25.26 , $25.33 , and $27.53 , respectively. 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. During 2019, the Company declared a quarterly cash dividend of $0.19 per share of common stock on January 29, 2019, April 25, 2019, July 25, 2019 and October 24, 2019. (2) Includes performance-based and market-based RSUs granted under the 2015 Plan according to their terms. The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to performance-based conditions that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 1.0 million shares. The aggregate number of shares subject to market-based conditions that would be issued if market criteria are achieved at target is 0.2 million shares. Depending on achievement of such market criteria, the range of shares that could be issued under these awards is zero to 0.4 million shares. (3) Total fair value of RSUs, RSAs, and PSAs vested during 2019 , 2018 , and 2017 was $170.0 million , $200.5 million , and $187.3 million , respectively. (4) 0.9 million shares of PSAs were modified in 2019, which relate to PSAs granted in 2018 and PSAs assumed by the Company in connection with acquisitions consummated in 2016. Compensation cost resulting from the modifications totaled $21.2 million to be recognized over the remaining terms of the modified awards. Shares Available for Grant The following table presents the stock activity and the total number of shares available for grant under the 2015 Plan (in millions): Number of Shares Balance as of December 31, 2018 21.9 Additional shares authorized 3.7 RSUs and PSAs granted (1) (15.5 ) RSUs and PSAs canceled (1)(2) 6.5 Balance as of December 31, 2019 16.6 ________________________________ (1) In May 2019, the 2015 Plan was amended, and the amendment removed the fungible share adjustment used to determine shares available for issuance. Under the original terms of the 2015 Plan, RSUs and PSAs with a per share or unit purchase price lower than 100% of the fair market value of the Company's common stock on the day of the grant were counted against shares authorized under the plan as two and one-tenth shares of common stock for each share subject to such award. Pursuant to the amendment, beginning on May 14, 2019, each share award granted under the 2015 Plan reduces the share reserve by one share and all share awards granted on May 14, 2019 and thereafter that are later forfeited, canceled or terminated are returned to the share reserve in the same manner. The number of shares subject to PSAs granted represents the maximum number of shares that may be issued pursuant to the award over its full term. (2) Canceled or expired options and canceled RSUs and PSAs under the 2006 Plan are no longer available for future grant under such plan; however, the number of shares available for grant under the 2015 Plan are increased by the amount of such canceled or expired options, RSUs or PSAs, as applicable, up to a maximum of 29.0 million additional shares of common stock, pursuant to the terms of the 2015 Plan. Employee Stock Purchase Plan During 2019 , 2018 , and 2017 , employees purchased 2.4 million , 2.5 million and 2.7 million shares of common stock through the ESPP at an average exercise price of $22.04 , $22.31 , and $20.83 per share, respectively. Valuation Assumptions The weighted-average assumptions used and the resulting estimates of fair value for ESPP and market-based RSUs were as follows: Years Ended December 31, 2019 2018 2017 ESPP: Volatility 27% 29% 25% Risk-free interest rate 2.1% 1.9% 0.9% Expected life (years) 1.2 1.2 0.5 Dividend yield 2.9% 2.7% 1.5% Weighted-average fair value per share $6.65 $6.93 $6.04 Market-based RSUs: Volatility 25% 28% 30% Risk-free interest rate 2.4% 2.4% 1.9% Dividend yield 2.8% 2.6% 1.4% Weighted-average fair value per share $27.32 $28.39 $19.30 Share-Based Compensation Expense Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Company's Consolidated Statements of Operations (in millions): Years Ended December 31, 2019 2018 2017 Cost of revenues - Product $ 5.7 $ 6.3 $ 4.6 Cost of revenues - Service 17.3 18.0 17.5 Research and development 94.0 120.6 86.6 Sales and marketing 56.0 51.1 55.6 General and administrative 29.2 21.1 23.2 Total $ 202.2 $ 217.1 $ 187.5 The following table summarizes share-based compensation expense by award type (in millions): Years Ended December 31, 2019 2018 2017 Stock options $ 7.7 $ 0.4 $ 0.5 RSUs, RSAs, and PSAs 176.5 198.2 171.3 ESPP 18.0 18.5 15.7 Total $ 202.2 $ 217.1 $ 187.5 For the years ended December 31, 2019 , 2018 and 2017 , the Company recognized tax benefits on total stock-based compensation expense, which are reflected in the income tax provision in the Consolidated Statements of Operations, of $29.6 million , $33.8 million , and $29.1 million , respectively. For the years ended December 31, 2019 , 2018 and 2017 , the realized tax benefit related to awards vested or exercised during the period was $30.6 million , $38.9 million and $64.1 million , respectively. These amounts do not include the indirect effects of stock-based awards, which primarily relate to the research and development tax credit. As of December 31, 2019 , the total unrecognized compensation cost related to unvested share-based awards was $280.7 million to be recognized over a weighted-average period of 1.6 years. 401(k) Plan The Company maintains a savings and retirement plan qualified under Section 401(k) of the Internal Revenue Code of 1986, as amended (the "IRC"). Employees meeting the eligibility requirements, as defined under the IRC, may contribute up to the statutory limits each year. The Company currently matches 30% of all eligible employee contributions which vest immediately. The Company’s matching contributions to the plan totaled $20.2 million , $20.2 million , and $21.1 million during 2019 , 2018 , and 2017 , respectively. Deferred Compensation Plan The Company’s NQDC plan is an unfunded and unsecured deferred compensation arrangement. Under the NQDC plan, officers and other senior employees may elect to defer a portion of their compensation and contribute such amounts to one or more investment funds. As of December 31, 2019 , the liability of the Company to the plan participants was $26.8 million , of which $4.1 million was included within other accrued liabilities and $22.7 million was included in other long-term liabilities on the Consolidated Balance Sheets. The Company had investments of $26.8 million correlating to the deferred compensation obligations, of which $4.1 million was included within prepaid expenses and other current assets and $22.7 million was included within other long-term assets on the Consolidated Balance Sheets. As of December 31, 2018 , the liability of the Company was $24.3 million , of which $3.6 million was included within other accrued liabilities and $20.7 million was included in other long-term liabilities on the Consolidated Balance Sheets. The Company had investments of $24.3 million correlating to the deferred compensation obligations, of which $3.6 million was included within prepaid expenses and other current assets and $20.7 million

Segments

Segments	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Segments	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): Years Ended December 31, 2019 2018 2017 Routing $ 1,623.2 $ 1,839.7 $ 2,189.5 Switching 901.0 934.4 963.4 Security 343.5 333.0 293.3 Total product 2,867.7 3,107.1 3,446.2 Total service 1,577.7 1,540.4 1,581.0 Total $ 4,445.4 $ 4,647.5 $ 5,027.2 The following table presents net revenues by customer vertical (in millions): Years Ended December 31, 2019 2018 2017 Cloud $ 1,059.8 $ 1,049.9 $ 1,310.7 Service Provider 1,827.8 2,066.7 2,319.4 Enterprise 1,557.8 1,530.9 1,397.1 Total $ 4,445.4 $ 4,647.5 $ 5,027.2 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): Years Ended December 31, 2019 2018 2017 Americas: United States $ 2,299.8 $ 2,339.1 $ 2,712.6 Other 218.2 202.1 234.6 Total Americas 2,518.0 2,541.2 2,947.2 Europe, Middle East, and Africa 1,215.3 1,290.8 1,195.8 Asia Pacific 712.1 815.5 884.2 Total $ 4,445.4 $ 4,647.5 $ 5,027.2 During the years ended December 31, 2019 , 2018 , and 2017 , no customer accounted for greater than 10% of the Company's net revenues. The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions): As of December 31, 2019 2018 United States $ 815.9 $ 941.7 International 200.8 128.5 Property and equipment, net and purchased intangible assets, net $ 1,016.7 $ 1,070.2 The Company tracks assets by physical location. The majority of the Company’s assets, excluding cash and cash equivalents and investments, as of December 31, 2019 and December 31, 2018 , were attributable to U.S. operations.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of pretax income are summarized as follows (in millions): Years Ended December 31, 2019 2018 2017 Domestic $ 296.2 $ 160.6 $ 474.2 Foreign 118.2 372.1 337.6 Total pretax income $ 414.4 $ 532.7 $ 811.8 The provision (benefit) for income taxes is summarized as follows (in millions): Years Ended December 31, 2019 2018 2017 Current provision (benefit): Federal $ 6.2 $ (126.1 ) $ 594.3 States 14.4 9.0 13.9 Foreign 48.5 38.9 45.4 Total current provision (benefit) 69.1 (78.2 ) 653.6 Deferred provision (benefit): Federal 0.8 36.6 (128.7 ) States 2.8 2.2 (17.7 ) Foreign (3.3 ) 5.2 (1.6 ) Total deferred provision (benefit) 0.3 44.0 (148.0 ) Total provision (benefit) for income taxes $ 69.4 $ (34.2 ) $ 505.6 The provision (benefit) for income taxes differs from the amount computed by applying the federal statutory rate of 21% for 2019, 21% for 2018, and 35% for 2017, respectively, to pretax income as follows (in millions): Years Ended December 31, 2019 2018 2017 Expected provision at statutory rate $ 87.0 $ 111.9 $ 284.1 State taxes, net of federal benefit 9.4 7.4 12.0 Foreign income at different tax rates 1.8 (12.8 ) (46.4 ) R&D tax credits (18.8 ) (22.1 ) (15.1 ) Share-based compensation 3.8 4.7 — Non-deductible compensation 3.3 1.9 1.6 Temporary differences not currently benefited 12.9 — — Recognition of previously unrecognized tax benefits (25.4 ) — — Lapses in federal statutes of limitations (7.5 ) (67.6 ) — Tax accounting method changes — (65.4 ) — Release of valuation allowance — — (1.7 ) Domestic production activities — — (12.4 ) Impact of the U.S. Tax Cuts and Jobs Act — 2.8 289.5 Other 2.9 5.0 (6.0 ) Total (benefit) provision for income taxes $ 69.4 $ (34.2 ) $ 505.6 In 2019, the Company recorded a $25.4 million benefit, including interest, related to the recognition of previously unrecognized tax benefits pursuant to the resolution of a tax audit and a $7.5 million benefit, including interest, for a lapse in statute of limitations. In 2018, the Company recorded a $67.6 million benefit, including interest, related to a lapse in statute of limitations relative to tax years 2010 through 2014, a $33.2 million benefit as a result of filing a change in accounting method for the tax recognition of deferred product revenue, and a $33.2 million benefit resulting from a tax accounting method change related to foreign deferred service revenue. The Tax Cuts and Jobs Act ("Tax Act") was enacted on December 22, 2017. The Tax Act introduced significant changes to U.S. income tax law. Effective January 1, 2018, the Tax Act reduced the U.S. federal corporate income tax rate from 35% to 21%, created a minimum tax on foreign earnings and imposed a one-time transition tax on accumulated foreign earnings through December 31, 2017. In 2017, the Company recorded provisional amounts for the effects of the Tax Act of $289.5 million primarily related to net taxes on accumulated foreign earnings and the re-measurement of the Company’s deferred tax assets at the revised U.S. statutory rate. In the fourth quarter of 2018, the Company completed its analysis to determine the effect of the Tax Act and recorded immaterial adjustments as of December 31, 2018. Deferred income taxes reflect the net tax effects of tax carry-forward items and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company's long-term deferred tax assets and deferred tax liabilities are as follows (in millions): As of December 31, 2019 2018 Deferred tax assets: Net operating loss carry-forwards $ 27.7 $ 12.9 Research and other credit carry-forwards 236.7 220.0 Deferred revenue 40.0 37.7 Share-based compensation 24.3 26.1 Cost sharing adjustment — 12.2 Reserves and accruals not currently deductible 55.8 62.7 Operating lease liabilities 48.3 — Other 12.0 13.2 Total deferred tax assets 444.8 384.8 Valuation allowance (249.4 ) (233.7 ) Deferred tax assets, net of valuation allowance 195.4 151.1 Deferred tax liabilities: Property and equipment basis differences (39.2 ) (40.6 ) Purchased intangibles (27.8 ) (13.7 ) Unremitted foreign earnings (23.7 ) (26.4 ) Deferred compensation and other (8.7 ) (8.9 ) Operating lease assets (41.1 ) — Total deferred tax liabilities (140.5 ) (89.6 ) Net deferred tax assets $ 54.9 $ 61.5 As of December 31, 2019 and 2018 , the Company had a valuation allowance on its U.S. domestic deferred tax assets of approximately $249.4 million and $233.7 million , respectively. The balance at December 31, 2019 consisted of approximately $221.6 million , $20.2 million and $3.1 million against the Company's California, Massachusetts and Canadian deferred tax assets, respectively, which the Company believes are not more likely than not to be utilized in future years. The remaining deferred tax assets for which the Company recorded a valuation allowance of approximately $4.5 million related to losses that are capital in nature and may carry forward to offset future capital gains only. The valuation allowance increased in 2019 and 2018 by $15.7 million and $19.2 million , respectively, primarily related to the change in California, Massachusetts and Canadian R&D tax credits. As of December 31, 2019 , the Company had federal and California net operating loss carry-forwards of approximately $101.2 million and $134.0 million , respectively. The California net operating loss carry-forwards of $134.0 million are expected to expire unused. The Company also had federal and California tax credit carry-forwards of approximately $4.7 million and $262.5 million , respectively. Unused net operating loss carry-forwards will expire at various dates beginning in the year 2020. The California tax credit carry-forwards will carry forward indefinitely. The Company provides deferred tax liabilities for all tax consequences associated with the undistributed earnings that are expected to be repatriated to subsidiaries' parent unless the subsidiaries' earnings are considered indefinitely reinvested. The Company has made no provision for deferred taxes on approximately $35.8 million of cumulative undistributed earnings of certain foreign subsidiaries through December 31, 2019. These earnings are considered indefinitely invested in operations of the subsidiaries, as the Company intends to utilize these amounts to fund future expansion of its operations. If these earnings were distributed to the parent, the Company would be subject to additional taxes of approximately $7.1 million . As of December 31, 2019 , 2018 , and 2017 , the total amount of gross unrecognized tax benefits was $151.3 million , $178.1 million , and $264.5 million , respectively. As of December 31, 2019 , approximately $150.9 million of the $151.3 million gross unrecognized tax benefits, if recognized, would affect the effective tax rate. A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows (in millions): Years Ended December 31, 2019 2018 2017 Balance at beginning of year $ 178.1 $ 264.5 $ 223.1 Tax positions related to current year: Additions 5.9 4.3 64.6 Tax positions related to prior years: Additions 0.8 12.7 1.8 Reductions (3.3 ) (33.8 ) (16.6 ) Settlements (22.5 ) (2.6 ) (4.0 ) Lapses in statutes of limitations (7.7 ) (67.0 ) (4.4 ) Balance at end of year $ 151.3 $ 178.1 $ 264.5 As of December 31, 2019 , 2018 , and 2017 , the Company had accrued interest and penalties related to unrecognized tax benefits of $29.9 million , $33.8 million , and $40.7 million , respectively, to other long-term liabilities in the Consolidated Balance Sheets. Due to the changes in the level of gross unrecognized tax benefits, the Company recognized a benefit for net interest and penalties of $2.8 million , $5.2 million and an expense of $8.5 million in its Consolidated Statements of Operations during the years ended December 31, 2019 , 2018 , and 2017 , respectively. The Company recognizes interest and penalties related to unrecognized tax benefits as a component of income tax expense. In December 2019, the Internal Revenue Service and the Company concluded the appeals process for the 2007 through 2009 tax years. As a result, the Company released $30.9 million of previously unrecognized tax benefits, including $8.4 million in interest and penalties. 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 $9.6 million to $24.6 million within the next twelve months due to the completion of tax review cycles in various tax jurisdictions and lapses of applicable statutes of limitation. The Company conducts business globally and, as a result, Juniper Networks or one or more of its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state and foreign jurisdictions. In the normal course of business, the Company is subject to examination by taxing authorities throughout the world, including such major jurisdictions as the Netherlands, U.K., France, Germany, Japan, China, Australia, India, and the U.S. With few exceptions, the Company is no longer subject to U.S. federal, state and local, and non-U.S. income tax examinations for years before 2009. The Company is currently under examination by the India tax authorities for the 2009 through 2015 tax years. The examinations by the India tax authorities are ongoing. The Company regularly assesses the likelihood of an adverse outcome resulting from such examinations. As of December 31, 2019 , the Company believes the resolution of the audits is unlikely to have a material effect on its consolidated financial condition or results of operations. The Company is pursuing all available administrative remedies relative to these ongoing matters. The Company believes that it has adequately provided for any reasonably foreseeable outcomes related to these proposed adjustments and the ultimate resolution of these matters is unlikely to have a material effect on its consolidated financial condition or results of operations; however, there is still a possibility that an adverse outcome of these matters could have a material effect on its consolidated financial condition and results of operations.

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Income per Share	Net Income per Share The Company computed basic and diluted net income per share as follows (in millions, except per share amounts): Years Ended December 31, 2019 2018 2017 Numerator: Net income $ 345.0 $ 566.9 $ 306.2 Denominator: Weighted-average shares used to compute basic net income per share 343.2 349.0 377.7 Dilutive effect of employee stock awards 5.0 5.4 6.5 Weighted-average shares used to compute diluted net income per share 348.2 354.4 384.2 Net income per share: Basic $ 1.01 $ 1.62 $ 0.81 Diluted $ 0.99 $ 1.60 $ 0.80 Anti-dilutive shares 4.7 3.9 1.1 Basic net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding for the period. Diluted net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Dilutive potential common shares consist of common shares issuable upon exercise of stock options, issuances of ESPP, and vesting of RSUs, RSAs, and PSAs. The Company includes the common shares underlying PSAs in the calculation of diluted net income per share only when they become contingently issuable. Anti-dilutive shares are excluded from the computation of diluted net income per share.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments 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. These obligations primarily result from contracts entered into for the acquisition of software development services and product development. For obligations with cancellation provisions, the amounts included in the preceding table were limited to the non-cancelable portion of the agreement terms or the minimum cancellation fee. The following table summarizes the Company’s unconditional purchase obligations for each of the next five years and thereafter as of December 31, 2019 (in millions): Years Ending December 31, Unconditional Purchase Obligations 2020 $ 42.0 2021 28.8 2022 21.0 2023 13.7 2024 6.9 Thereafter 1.4 Total $ 113.8 In December 2018, the Company entered into a Master Services Agreement and certain Statements of Work, (collectively, the “Agreement”) with International Business Machines Corporation ("IBM") pursuant to which the Company will outsource significant portions of its IT and other administrative functions following a transition period. Under the Agreement, IBM will provide the Company a broad range of IT services such as applications, including support, development and maintenance; infrastructure management and support, including for servers, storage and network devices; and end user support including service desk. The Agreement has an initial term through 2026 over which period the Company will pay IBM a combination of fixed and variable fees, fluctuating based on the Company's actual need for the services utilized. As of December 31, 2019, the Company expects to pay IBM approximately $300.0 million . The table above does not include fees payable to IBM under the contract as the Company is unable to make a reasonably reliable estimate of the amount of the payments related to this contract due to uncertainties in the usage of the services. In December 2019, the Company entered into a 15-year Energy Services Agreement with a Supplier to purchase energy and environmental attributes generated from a third-party fuel cell systems, which will be installed, operated, and maintained by the Supplier on the Company's premises. The Company will pay Supplier service fees that will fluctuate based on the actual amount of electricity delivered to the Company during a given operational year. As of December 31, 2019, the Company expects to pay Supplier approximately $29.0 million over a 15-year period. The table above does not include fees payable to this Supplier due to uncertainties associated with system outputs. Leases The Company leases its facilities and certain equipment under non-cancelable operating leases that have remaining lease terms of 1 to 10 years and 1 to 4 years, respectively. Each leased facility is subject to an individual lease or sublease, which could provide various options to extend or terminate the lease agreement. Facilities are primarily comprised of corporate offices, data centers, and R&D facilities. Equipment includes vehicles and various office equipment. The Company also has variable lease payments that are primarily comprised of common area maintenance and utility charges. The Company's lease agreements do not contain any residual value guarantees or restrictive covenants. The components of lease costs and other information related to leases were as follows (in millions, except years and percentages): December 31, 2019 Operating lease cost $ 50.3 Variable lease cost 12.6 Total lease cost $ 62.9 Operating cash outflows from operating leases $ 49.6 ROU assets obtained in exchange for new operating lease liabilities $ 14.0 Weighted average remaining lease term (years) 5.5 Weighted average discount rate 3.9 % As of December 31, 2019 , future operating lease payments for each of the next five years and thereafter is as follows (in millions): Years Ending December 31, Amount 2020 $ 49.3 2021 45.3 2022 36.3 2023 30.6 2024 26.8 Thereafter 37.7 Total lease payments 226.0 Less: interest (25.6 ) Total $ 200.4 Balance Sheet Information Other accrued liabilities 42.3 Long-term operating lease liabilities 158.1 Total $ 200.4 As of December 31, 2018 , prior to the adoption of ASC 842, future minimum payments under non-cancelable operating and other lease arrangements for each of the next five years and thereafter were as follows (in millions): Leases Years Ending December 31, Operating Leases Other Lease Arrangement (*) 2019 $ 33.7 $ 13.1 2020 30.7 13.3 2021 24.3 13.6 2022 17.0 13.9 2023 14.3 14.2 Thereafter 26.3 32.9 Total $ 146.3 $ 101.0 _______________ (*) Represents a build-to-suit lease arrangement entered into in July 2015. Rent expense for 2018 and 2017 was approximately $39.0 million and $39.3 million , respectively. Rent expense in prior years was recognized in accordance with ASC 840, Leases , using the straight-line method over the term of a lease. 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. The following table summarizes the Company’s purchase commitments for each of the next five years and thereafter as of December 31, 2019 (in millions): Years Ending December 31, Purchase Commitments 2020 $ 794.3 2021 230.7 2022 220.1 2023 226.4 Thereafter — Total $ 1,471.5 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 December 31, 2019 , the Company had accrued $28.6 million based on its estimate of such charges. Debt and Interest Payment on Debt As of December 31, 2019 , the Company held total outstanding debt consisting of the Notes with a carrying value of $1,683.9 million . See Note 10, Debt and Financing , for further discussion of the Company's long-term debt and expected future principal maturities. Tax Liability In the fourth quarter of 2018, the Company completed its analysis to determine the effect of the Tax Act and recorded immaterial adjustments as of December 31, 2018. The Company has elected to pay its transition tax, net of applicable tax refunds, over the eight-year period provided in the Tax Act. The long-term income taxes payable of $245.2 million represents the remaining balance of the Company's transition tax obligation. As of December 31, 2019 , the Company had $127.4 million included in long-term income taxes payable on the Consolidated Balance Sheets for unrecognized tax positions. At this time, the Company is unable to make a reasonably reliable estimate of the timing of payments related to this amount due to uncertainties in the timing of tax audit outcomes. Guarantees The Company enters into agreements with customers that contain indemnification provisions relating to potential situations where claims could be alleged that the Company’s products solely, or in combination with other third-party products, infringe the intellectual property rights of a third-party. As of December 31, 2019 and 2018 , the Company recorded $9.0 million and $11.9 million , respectively, for such indemnification obligations in other accrued liabilities and other long-term liabilities on the Consolidated Balance Sheets. The Company also has financial guarantees consisting of guarantees of product and service performance and standby letters of credit for certain lease facilities and insurance programs of $30.6 million and $23.1 million , as of December 31, 2019 and December 31, 2018 , respectively. Legal Proceedings The Company is involved in 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 these matters, and while there can be no assurances and the outcome of these matters is currently not determinable, the Company currently believes that none of these 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 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 those 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.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) The table below sets forth selected unaudited financial data for each quarter of the years ended December 31, 2019 and December 31, 2018 (in millions, except per share amounts): Year Ended December 31, 2019 Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues $ 1,001.7 $ 1,102.5 $ 1,133.1 $ 1,208.1 $ 1,082.6 $ 1,204.1 $ 1,179.8 $ 1,181.0 Gross margin 582.3 636.8 678.4 719.3 618.4 700.9 711.0 710.9 Income before income taxes 44.5 77.8 118.1 174.0 41.4 150.9 152.0 188.4 Net income (1) $ 31.1 $ 46.2 $ 99.3 $ 168.4 $ 34.4 $ 116.5 $ 223.8 $ 192.2 Net income per share: (2) Basic $ 0.09 $ 0.13 $ 0.29 $ 0.50 $ 0.10 $ 0.33 $ 0.65 $ 0.56 Diluted $ 0.09 $ 0.13 $ 0.29 $ 0.49 $ 0.10 $ 0.33 $ 0.64 $ 0.55 _______________ (1) Net income for the third and fourth quarters of 2018 include a lower statutory tax rate due to the Tax Act and tax benefits related to items unique to 2018. See Note 14, Income Taxes , for further discussion. (2) Net income per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Dividend Declaration On January 27, 2020 , the Company announced that the Board declared a quarterly cash dividend of $0.20 per share of common stock to be paid on March 23, 2020 to stockholders of record as of the close of business on March 2, 2020 . Stock Repurchase Activities During the first quarter of 2020, the ASR was completed and the Company received an additional 1.8 million shares from the financial institution. These 1.8 million shares will be retired in the first quarter of 2020. The completion of the ASR resulted in a total settlement 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. Subsequent to December 31, 2019, through the date of filing of this Report (the "filing date"), the Company also repurchased 7.6 million shares of its common stock in the open market, for an aggregate purchase price of $179.8 million at an average price of $23.68 per share, under the 2018 Stock Repurchase Program. Repurchases of approximately 6.7 million shares were settled prior to the filing of this Report and the remaining shares will be settled after the filing date. The Company has an aggregate of $1.5 billion of authorized funds remaining under the Stock Repurchase Program as of the filing date.

Schedule II- Valuation and Qual

Schedule II- Valuation and Qualifying Account	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Account	Juniper Networks, Inc. Schedule II - Valuation and Qualifying Accounts Years Ended December 31, 2019 , 2018 , and 2017 (In millions) Allowance for Doubtful Accounts Balance at Beginning of Year Charged to (Reversed from) Costs and Expenses Write-offs, Net of Recoveries Balance at End of Year 2019 $ 4.9 $ 1.7 $ (1.1 ) $ 5.5 2018 $ 5.7 $ (0.8 ) $ — $ 4.9 2017 $ 7.6 $ (2.0 ) $ 0.1 $ 5.7 Additions Sales Return Reserve Balance at Beginning of Year Charged as a Reduction in Revenues Charged to Other Accounts Used Balance at End of Year 2019 $ 32.7 $ 59.5 $ — $ (67.4 ) $ 24.8 2018 (*) $ 44.5 $ 70.7 $ — $ (82.5 ) $ 32.7 2017 $ 71.4 $ 25.0 $ 65.9 $ (107.1 ) $ 55.2 ________________________________ (*) Upon adoption of Topic 606, the Company recorded a reduction of $10.7 million as part of the cumulative effect adjustment to the January 1, 2018 opening accumulated deficit balance on the Consolidated Balance Sheet. All other schedules have been omitted as the required information is not applicable or the information is presented in the Consolidated Financial Statements or notes thereto under Item 8 herein.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements, which include the Company and its wholly-owned subsidiaries, are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). All intercompany balances and transactions have been eliminated.
Use of Estimates	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 Consolidated Financial Statements and the accompanying notes. The Company bases its estimates and assumptions on current facts, historical experience, and various other factors that it believes are reasonable under the circumstances, to determine the carrying values of assets and liabilities that are not readily apparent from other sources. To the extent there are material differences between the Company's estimates and the actual results, the Company's future consolidated results of operation may be affected.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, demand deposits with banks, highly liquid investments in money market funds, commercial paper, government securities, certificates of deposits, time deposits, and corporate debt securities, which are readily convertible into cash. All highly liquid investments with original maturities of three months or less from Juniper's purchase date are classified as cash equivalents.
Investments in Available-for-Sale Debt Securities and Equity Securities	Investments in Available-for-Sale Debt Securities The Company's investments in debt securities are classified as available-for-sale and include the Company's fixed income securities and investments in privately-held companies, consisting of debt and redeemable preferred stock securities. Fixed income securities are initially recorded at cost and periodically adjusted to fair value in the Consolidated Balance Sheets. Unrealized gains and losses on these investments are reported as a separate component of accumulated other comprehensive loss in the Consolidated Balance Sheets. Realized gains and losses are determined based on the specific identification method and are reported in the Consolidated Statements of Operations. Fixed income securities primarily consist of asset-backed securities, certificate of deposits, commercial paper, corporate debt securities, time deposits, foreign government debt securities, U.S. government agency securities, and U.S. treasury securities. The Company periodically evaluates these investments to determine if impairment charges are required. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time the investment has been in a loss position, the extent to which the fair value has been less than the Company's cost basis, the investment's financial condition, and the near-term prospects of the investee. If the Company determines that the decline in an investment's value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. The Company's privately-held debt and redeemable preferred stock securities are included in other long-term assets in the Consolidated Balance Sheets and are recorded at fair value. Fair value is reassessed when the Company is made aware of information indicating a change in the enterprise value of the investee, including known acquisition offers, subsequent funding rounds, and investee's plans for liquidation. The Company periodically evaluates these securities for indicators of impairment, including the inability to recover a portion of or the entire carrying amount of the investment, the inability of the investee to sustain earnings, the reduction in or termination of financial commitment to the investee from other investors, the intention to sell the investment, and whether it is more likely than not that the Company will be required to sell the investment before recovery of the entire amortized cost basis. If the Company determines that the decline in an investment's value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. Investments in Equity Securities The Company's investments in equity securities with readily determinable fair values consist of money market funds, the non-qualified compensation plan ("NQDC") that is invested in mutual funds, and investments in public companies. These investments are measured at fair value with changes in fair value recognized in the Consolidated Statements of Operations. Equity securities without readily determinable fair values include the Company's investments in privately-held companies consisting of non-redeemable preferred stock and common stock securities. The Company accounts for these securities at cost, adjusted for changes from observable transactions for identical or similar investments of the same issuer, less impairments. Fair value of these equity securities is reassessed when the Company identifies observable price changes indicating that an adjustment upward or downward to the carrying value is necessary. Any observable changes in fair value are recognized in earnings as of the date that the observable transaction took place, rather than the current reporting date. In addition, the Company periodically evaluates equity securities without readily determinable fair values to determine if impairment charges are required by evaluating whether an event or change in circumstance has occurred that may have a significant adverse effect on the fair value of the investment. A qualitative assessment is performed each reporting period to assess whether there are any impairment indicators, including, but not limited to, significant deterioration in the investee's earnings performance; credit rating; asset quality or business prospects; adverse change in the regulatory, economic, or technological environment; change in the general market condition of the geographic area or industry; acquisition offers; and the ability to continue as a going concern. If such indicators are present, the Company estimates the fair value of impaired investments and recognizes an impairment loss in the Consolidated Statement of Operations equal to the difference between the carrying value and fair value.
Fair Value	Fair Value Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it transacts, and considers assumptions that market participants would use when pricing the asset or liability. The Company applies the following fair value hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. These inputs are valued using market-based approaches. Level 3 – Inputs are unobservable inputs based on the Company’s assumptions. These inputs, if any, are valued using internal financial models.
Derivatives	Derivative Instruments The Company uses derivative instruments, primarily foreign currency forward and interest rate swap contracts, to hedge certain foreign currency and interest rate exposures. The Company does not enter into derivatives for speculative or trading purposes. The Company uses foreign currency forward contracts to hedge certain forecasted foreign currency transactions relating to operating expenses. These derivatives are designated as cash flow hedges, which are carried at fair value with the derivative's gain or loss is initially reported as a component of accumulated other comprehensive loss, and upon occurrence of the forecasted transaction, is subsequently reclassified into the costs of services or operating expense line item to which the hedged transaction relates. Cash flows from such hedges are classified as operating activities. The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in non-functional currencies. These derivatives are carried at fair value with changes recorded in other expense, net in the Consolidated Statements of Operations in the same period as the changes in the fair value from the re-measurement of the underlying assets and liabilities. Cash flows from such derivatives are classified as operating activities. The Company uses interest rate swaps to convert certain of our fixed interest rate notes to floating interest rates based on the London InterBank Offered Rate (LIBOR). All interest rate swaps will expire within ten years or less. The Company recognizes the change in fair value of the derivative instrument, as well as the offsetting change in the fair value of the hedged item, in Other expense, net in the Consolidated Statements of Operations in the period of change. These derivatives are classified in the Consolidated Statements of Cash Flows in the same section as the underlying item. The Company presents its derivative assets and derivative liabilities on a gross basis in the Consolidated Balance Sheets. However, under agreements containing provisions on netting with certain counterparties of foreign exchange contracts, subject to applicable requirements, the Company is allowed to net-settle transactions on the same date in the same currency, with a single net amount payable by one party to the other. The Company is neither required to pledge nor entitled to receive cash collateral related to these derivative transactions.
Inventory	Inventory Inventory consists primarily of component parts to be used in the manufacturing process and finished goods in-transit, and is stated at the lower of cost or net realizable value. In addition, the Company purchases and holds inventory to provide adequate component supplies over the life of the underlying products. Cost is computed using standard cost, which approximates actual cost, on a first-in, first-out basis. A charge is recorded to cost of product when inventory is determined to be in excess of anticipated demand or considered obsolete. At the point of loss recognition, a new, lower-cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in the restoration or increase in the newly established cost basis.
Lessee, Leases	Leases The Company determines if an arrangement is a lease at inception. The Company evaluates classification of leases as either operating or finance at commencement and, as necessary, at modification. As of December 31, 2019 , the Company did no t have any finance leases. Operating leases are included in operating lease right-of-use ("ROU") assets, other accrued liabilities, and operating lease liabilities on the Company's Consolidated Balance Sheets. ROU assets represent the Company's right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized on the commencement date based on the present value of lease payments over the lease term. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the incremental borrowing rate on January 1, 2019 for operating leases that commenced prior to that date. The operating lease ROU asset also includes any lease payments made prior to lease commencement and excludes lease incentives. Variable lease payments not dependent on an index or a rate, are expensed as incurred and are not included within the ROU asset and lease liability calculation. Variable lease payments primarily include reimbursements of costs incurred by lessors for common area maintenance and utilities. The Company's lease terms are the noncancelable period, including any rent-free periods provided by the lessor, and include options to extend or terminate the lease when it is reasonably certain that it will exercise that option. At lease inception, and in subsequent periods as necessary, the Company estimates the lease term based on its assessment of extension and termination options that are reasonably certain to be exercised. Lease costs are recognized on a straight-line basis over the lease term. The Company does not separate non-lease components from lease components for all underlying classes of assets. In addition, the Company does not recognize ROU assets and lease liabilities for short-term leases, which have a lease term of twelve months or less and do not include an option to purchase the underlying asset that the Company is reasonably certain to exercise. Lease cost for short-term leases is recognized on a straight-line basis over the lease term.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 1.5 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 10 to 40 Leasehold improvements Lease term, not to exceed 10 years Land is not depreciated. Construction-in-process is related to the construction or development of property and equipment that have not yet been placed in service for their intended use.
Business Combinations Policy	Business Combinations The purchase price of an acquired entity is allocated to tangible assets, liabilities, and intangible assets, including in-process research and development (IPR&D) based on their estimated fair values with the residual of the purchase price recorded as goodwill. The determination of the value of the intangible assets acquired involves certain estimates, such as expected future cash flows, which include consideration of future growth rates and margins, attrition rates, future changes in technology, discount rates, and the expected use of the acquired assets. These factors are also considered in determining the useful life of the acquired intangible assets. IPR&D is initially capitalized at fair value as an intangible asset with an indefinite life and assessed for impairment thereafter. When an IPR&D project is completed, the IPR&D is reclassed as an amortizable purchased intangible asset and amortized over the asset’s estimated useful life. Acquisition related expenses are recognized separately from business combination and are expensed as incurred. The Company's Consolidated Financial Statements include the operating results of acquired businesses from the date of each acquisition.
Goodwill and Other Long-Lived Assets	Goodwill and Intangible Assets Goodwill is tested for impairment annually during the fourth quarter or more frequently if certain circumstances indicate the carrying value of goodwill is impaired. Goodwill is tested for impairment at the reporting unit level. A qualitative assessment is first performed to determine whether it is necessary to quantitatively test goodwill for impairment. This initial assessment includes, among others, consideration of macroeconomic conditions and financial performance. If the qualitative assessment indicates that it is more likely than not that an impairment exists, a quantitative analysis is performed by determining the fair value of each reporting unit using a combination of the discounted cash flow and the market approaches. Goodwill is considered impaired if the carrying value of the reporting unit exceeds its fair value. An impairment loss is recognized to the extent that the carrying amount of goodwill exceeds the asset's implied fair value. We conducted our annual impairment test of goodwill during the fourth quarters of 2019 and 2018 and determined that no adjustment to the carrying value of goodwill for any reporting units was required. Intangible assets consist of existing technology, customer relationships, and trade name, which are amortized over the period of estimated benefit using the straight-line method and estimated useful lives of 4 or 5 years. Other intangible assets acquired in a business combination related to IPR&D projects are considered to be indefinite-lived until the completion or abandonment of the associated research and development efforts. Indefinite-lived intangibles are not amortized into the results of operations but instead are evaluated for impairment. If and when development is complete, the associated assets would be deemed finite-lived and would be amortized as cost of revenues over their respective estimated useful lives at that point in time. If the research and development project is abandoned, the acquired IPR&D assets are written off and charged to expense in the period of abandonment. Impairment of Long-lived Assets Long-lived assets, such as property, plant, and equipment, ROU assets, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group, to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. An impairment charge is recognized by the amount by which the carrying amount of the asset, or asset group, exceeds its fair value.
Warranty Reserves	Warranty Reserves The Company generally offers a one -year warranty on most of its hardware products, and a 90 -day warranty on the media that contains the software embedded in the products. Warranty costs are recognized as part of the Company's cost of sales based on associated material costs, logistics costs, labor costs, and overhead at the time revenue is recognized. Material costs are estimated primarily based upon the historical costs to repair or replace product returns within the warranty period. Labor, logistics and overhead costs are estimated primarily based upon historical trends in the cost to support customer cases within the warranty period. Warranty reserve is reported within other accrued liabilities in the Consolidated Balance Sheets.
Contract Manufacturer Liabilities	Contract Manufacturer Liabilities The Company establishes a liability for non-cancelable, non-returnable purchase commitments with its contract manufacturers for carrying charges, quantities in excess of its demand forecasts, or obsolete material charges for components purchased by the contract manufacturers to meet the Company’s demand forecast or customer orders. The demand forecasts are based upon historical trends and analysis from the Company's sales and marketing organizations, adjusted for overall market conditions.
Loss Contingencies	Loss Contingencies The Company is subject to the possibility of various loss contingencies arising in the ordinary course of business. Management considers the likelihood of loss related to an asset, or the incurrence of a liability, as well as its ability to reasonably estimate the amount of loss, in determining loss contingencies. An estimated loss contingency is accrued when it is probable that an asset has been impaired or a liability has been incurred and the amount of loss can be reasonably estimated. The Company regularly evaluates current information available to determine whether such accruals should be adjusted and whether new accruals are required.
Foreign Currency	Foreign Currency Assets and liabilities of foreign operations with non-U.S. Dollar functional currency are translated to U.S. Dollars using exchange rates in effect at the end of the period. Revenue and expenses are translated to U.S. Dollars using rates that approximate those in effect during the period. The resulting translation adjustments are included in the Company’s Consolidated Balance Sheets in the stockholders’ equity section as a component of accumulated other comprehensive loss. The Company remeasures monetary assets and monetary liabilities in non-functional currencies and records the resulting foreign exchange transaction gains and losses in other expense, net in the Consolidated Statements of Operations.
Revenue Recognition	Revenue Recognition Revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services by following a five-step process, (1) identify the contract with a customer, (2) identify the performance obligations in the contract, (3) determine the transaction price, (4) allocate the transaction price, and (5) recognize revenue when or as the Company satisfies a performance obligation, as further described below. Identify the contract with a customer . The Company generally considers a sales contract and/or agreement with an approved purchase order as a customer contract provided that collection is considered probable, which is assessed based on the creditworthiness of the customer as determined by credit checks, payment histories, and/or other circumstances. The Company combines contracts with a customer if contracts are negotiated with a single commercial substance or contain price dependencies. Identify the performance obligations in the contract . Product performance obligations include hardware and software licenses and service performance obligations include hardware maintenance, software post-contract support, training, and professional services. Certain software licenses and related post-contract support are combined into a single performance obligation when the maintenance updates are critical to the continued delivery of the software functionality. Determine the transaction price . The transaction price for the Company’s contracts with its customers consists of both fixed and variable consideration provided it is probable that a significant reversal of revenue will not occur when the uncertainty related to variable consideration is resolved. Fixed consideration includes amounts to be contractually billed to the customer while variable consideration includes estimates for rights of return, rebates, and price protection, which are based on historical sales returns and price protection credits, specific criteria outlined in rebate agreements, and other factors known at the time. The Company generally invoices customers for hardware, software licenses and related maintenance arrangements at time of delivery, and professional services either upfront or upon meeting certain milestones. Customer invoices are generally due within 30 to 90 days after issuance. The Company’s contracts with customers typically do not include significant financing components as the period between the transfer of performance obligations and timing of payment are generally within one year. Allocate the transaction price to the performance obligations in the contract . For contracts that contain multiple performance obligations, the Company allocates the transaction price to the performance obligations on a relative standalone selling price basis. Standalone selling prices are based on multiple factors including, but not limited to historical discounting trends for products and services, pricing practices in different geographies and through different sales channels, gross margin objectives, internal costs, competitor pricing strategies, and industry technology lifecycles. Recognize revenue when or as the Company satisfies a performance obligation . Revenue for hardware and certain software licenses, are recognized at a point in time, which is generally upon shipment or delivery. Certain software licenses combined with post-contract support are recognized over time on a ratable basis over the term of the license. Revenue for maintenance and software post-contract support is recognized over time on a ratable basis over the contract term. Revenue from training and professional services is recognized over time as services are completed or ratably over the contractual period of generally one year or less. Deferred product revenue represents unrecognized revenue related to undelivered product commitments and other shipments that have not met revenue recognition criteria. Deferred service revenue represents billed amounts for service contracts, which include technical support, hardware and software maintenance, professional services, and training, for which services have not been rendered. Revenue is recognized net of any taxes collected, which are subsequently remitted to governmental authorities.
Deferred Commissions	Deferred Commissions Sales commissions earned by the Company’s sales force are considered incremental and recoverable costs of obtaining a contract with a customer. These costs are recorded as prepaid expenses or other longer assets and are deferred and then amortized over a period of benefit which is typically over the term of the customer contracts. Amortization expense is included in sales and marketing expenses in the accompanying Consolidated Statements of Operations.
Research and Development	Research and Development Costs to research, design, and develop the Company's products are expensed as incurred.
Software Development Costs	Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins when a product's technological feasibility has been established and ends when a product is available for general release to customers. Generally, the Company's products are released soon after technological feasibility has been established. As a result, costs incurred between achieving technological feasibility and product general availability have not been significant. The Company capitalizes costs associated with internal-use software systems during the application development stage. Such capitalized costs include external direct costs incurred in developing or obtaining the applications and payroll and payroll-related costs for employees, who are directly associated with the development of the applications.
Advertising	Advertising
Share-Based Compensation	Share-Based Compensation The Company measures and recognizes compensation cost for all share-based awards made to employees and directors, including employee stock options, restricted stock awards ("RSAs"), restricted stock units ("RSUs"), performance share awards ("PSAs") and employee stock purchases related to the Employee Stock Purchase Plan ("ESPP"). For service condition only awards, share-based compensation expense is based on the fair value of the underlying awards and amortized on a straight-line basis. For PSAs, share-based compensation expense is amortized on a straight-line basis for each separate vesting portion of the awards. The Company accounts for forfeitures as they occur. The Company utilizes the Black-Scholes-Merton (“BSM”) option-pricing model to estimate the fair value of its ESPP purchase rights. The BSM model requires various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, expected life, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected life of the Company’s ESPP. The expected life of ESPP purchase rights approximates the offering period. The Company determines the grant date fair value of its RSUs, RSAs, and PSAs based on the closing market price of the Company’s common stock on the date of grant, adjusted by the present value of the 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. For market-based RSUs, the Company estimates the fair value and derived service period using the Monte Carlo simulation option pricing model ("Monte Carlo model"). The determination of the grant date fair value and derived service periods using the Monte Carlo model is affected by the Company's stock price, comparative market-based returns, as well as various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors, including historical volatility of the Company’s common stock over the contractual life of the Company's market-based RSUs.
Provision for Income Taxes	Provision for Income Taxes Deferred tax assets and liabilities are recognized for the expected tax consequences of temporary differences between the tax basis of assets and liabilities and their reported amounts. Valuation allowances are recorded to reduce deferred tax assets to the amount that will more likely than not be realized. The Company accounts for uncertainty in income taxes using a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company classifies the liability for unrecognized tax benefits as current to the extent that the Company anticipates payment (or receipt) of cash within one year . Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes. The Company accounts for the current impacts of U.S. tax on certain foreign subsidiaries income, which is referred to as Global Intangible Low-Taxed Income in the year earned.
Concentrations of Risk	Concentrations of Risk Financial instruments that subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, investments, derivatives, and accounts receivable. The Company invests only in high-quality credit instruments and maintains its cash, cash equivalents and available-for-sale investments in fixed income securities with several high-quality institutions. Deposits held with banks, including those held in foreign branches of global banks, may exceed the amount of insurance provided on such deposits. We mitigate the concentration of credit risk in our investment portfolio through diversification of the investments in various industries and asset classes, and limits to the amount of credit exposure to any single issuer and credit rating. The Company’s derivatives expose it to credit risk to the extent that counterparties may be unable to meet the terms of the agreement. To mitigate concentration of risk related to its derivatives, the Company establishes counterparty limits to major credit-worthy financial institutions. In addition, the potential risk of loss with any one counterparty resulting from this type of credit risk is monitored and the derivatives transacted with these entities are typically relatively short in duration. Therefore, the Company does not expect material losses as a result of defaults by counterparties. Generally, credit risk with respect to accounts receivable is diversified due to the number of entities comprising the Company's customer base and their dispersion across different geographic locations throughout the world. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. During the years ended December 31, 2019 , 2018 , and 2017 , no single customer accounted for 10% or more of net revenues. The Company relies on sole suppliers for certain of its components such as application-specific integrated circuits ("ASICs") and custom sheet metal. Additionally, the Company relies primarily on a limited number of significant independent contract manufacturers and original design manufacturers for the production of its products. The inability of any supplier or manufacturer to fulfill supply requirements of the Company could negatively impact future operating results.
Recently Adopted Accounting Standard and Recent Accounting Standards Not Yet Adopted	Recently Adopted Accounting Standards Cloud Computing Arrangement: On January 1, 2019, the Company early adopted FASB ASU No. 2018-15 (Subtopic 350-40) Intangibles — Goodwill and Other-Internal-Use Software: Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which provides guidance on a customer's accounting for implementation, set-up, and other upfront costs incurred in a cloud computing arrangement that is hosted by a service contract. The Company adopted the standard under the prospective approach. The adoption did not have a material impact on the Consolidated Financial Statements. Derivatives and Hedging: On January 1, 2019, the Company adopted FASB ASU No. 2017-12 (Topic 815) Derivatives and Hedging — Targeted Improvements to Accounting for Hedging Activities , and an amendment thereafter, which expands an entity's ability to hedge financial and nonfinancial risk components and amends how companies assess effectiveness as well as changes to the presentation and disclosure requirements. The Company adopted the standard under the modified retrospective approach, and its amendment and presentation and disclosure requirements on a prospective basis. The adoption did not have a material impact on the Consolidated Financial Statements. See Note 6, Derivative Instruments for additional disclosures required upon adopting the standard. Amortization on Purchased Callable Debt Securities: On January 1, 2019, the Company adopted FASB ASU No. 2017-08 Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which shortens the amortization period for the premium on certain purchased callable debt securities to the earliest call date. The standard will not impact debt securities held at a discount. The Company adopted the standard under the modified retrospective approach. The adoption did not have a material impact on the Consolidated Financial Statements. Leases: On January 1, 2019, the Company adopted FASB ASU No. 2016-02, Leases (Topic 842) , and the related subsequent amendments ("ASC 842"), which require recognition by the lessees of right-of-use ("ROU") assets and lease liabilities for most leases on the Company's Consolidated Balance Sheets. The Company adopted the new standard under the modified retrospective approach and recorded a cumulative-effect adjustment to the opening balance of accumulated deficit as of the effective date. Under the modified retrospective method, financial results reported in periods prior to 2019 are unchanged. The Company elected the package of practical expedients, which did not require the reassessment of existing leases under the new guidance. The Company also elected not to separate non-lease components from lease components and to not recognize ROU assets and lease liabilities for short-term leases. The cumulative effect of the adjustments made to the Company's Consolidated Balance Sheet as of the adoption date is detailed as follows (in millions): December 31, 2018 January 1, 2019 As reported Adjustments due to ASC 842 As adjusted Assets: Prepaid expenses and other current assets $ 268.1 $ (1.4 ) $ 266.7 Property and equipment, net 951.7 (42.9 ) 908.8 Operating lease assets — 192.5 192.5 Other long-term assets 403.5 1.3 404.8 Total assets $ 9,363.3 $ 149.5 $ 9,512.8 Liabilities: Other accrued liabilities $ 233.5 $ 35.6 $ 269.1 Long-term operating lease liabilities — 185.5 185.5 Other long-term liabilities 119.8 (66.7 ) 53.1 Total liabilities $ 4,540.1 $ 154.4 $ 4,694.5 Stockholders' equity: Accumulated deficit $ (2,831.4 ) $ (4.9 ) $ (2,836.3 ) The adoption of the standard had no impact on the Company's Consolidated Statements of Operations and Consolidated Statements of Cash Flows or debt-covenant compliance under its current agreements. See Note 16, Commitments and Contingencies, for additional disclosures required upon adopting the standard. Recent Accounting Standards Not Yet Adopted 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 of the income tax accounting guidance related to intraperiod tax allocation exception to the incremental approach, interim-period accounting for enacted change in tax law, and the year-to-date loss limitation in interim period tax accounting. 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. Fair Value Measurement: In August 2018, the FASB issued 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. This ASU is to be applied on a prospective basis for certain modified or new disclosure requirements, and all other amendments in the standard are to be applied on a retrospective basis. The new standard is effective for interim and annual periods beginning after December 15, 2019. The Company does not expect the adoption to have a material impact on its Consolidated Financial Statements. Simplifying the Test for Goodwill Impairment: In January 2017, the FASB issued ASU No. 2017-04 (Topic 350) Intangibles—Goodwill and Other: Simplifying the Test for Goodwill Impairmen t, 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. This ASU will be applied on a prospective basis and is effective for interim and annual periods beginning after December 15, 2019. The Company does not expect the adoption to have a material impact on its Consolidated Financial Statements. Credit Losses on Financial Instruments: In June 2016, the FASB issued ASU 2016-13 "Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" , which was further clarified by FASB through issuance of additional related ASUs, requires the measurement and recognition of 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 will adopt ASU 2016-13 effective January 1, 2020 on a modified retrospective basis with the cumulative effect of adoption recorded as an adjustment to retained earnings. Upon adoption, we will implement new credit loss models and update processes and accounting controls. The Company does not expect the adoption of the new standard to have a significant impact on the Company’s Consolidated Financial Statements.
Earnings Per Share	Basic net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding for the period. Diluted net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Dilutive potential common shares consist of common shares issuable upon exercise of stock options, issuances of ESPP, and vesting of RSUs, RSAs, and PSAs. The Company includes the common shares underlying PSAs in the calculation of diluted net income per share only when they become contingently issuable. Anti-dilutive shares are excluded from the computation of diluted net income per share.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Property and equipment useful life	Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 1.5 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 10 to 40 Leasehold improvements Lease term, not to exceed 10 years
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	The cumulative effect of the adjustments made to the Company's Consolidated Balance Sheet as of the adoption date is detailed as follows (in millions): December 31, 2018 January 1, 2019 As reported Adjustments due to ASC 842 As adjusted Assets: Prepaid expenses and other current assets $ 268.1 $ (1.4 ) $ 266.7 Property and equipment, net 951.7 (42.9 ) 908.8 Operating lease assets — 192.5 192.5 Other long-term assets 403.5 1.3 404.8 Total assets $ 9,363.3 $ 149.5 $ 9,512.8 Liabilities: Other accrued liabilities $ 233.5 $ 35.6 $ 269.1 Long-term operating lease liabilities — 185.5 185.5 Other long-term liabilities 119.8 (66.7 ) 53.1 Total liabilities $ 4,540.1 $ 154.4 $ 4,694.5 Stockholders' equity: Accumulated deficit $ (2,831.4 ) $ (4.9 ) $ (2,836.3 )

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2019
Business Combinations [Abstract]
Schedule of estimated fair values of assets acquired and liabilities assumed	The following table summarizes the fair values of the assets acquired and liabilities assumed at the acquisition dates (in millions): 2019 2018 2017 Mist HTBase Cyphort Net tangible assets acquired/(liabilities) assumed $ 28.3 $ (1.0 ) $ 1.4 Intangible assets 102.0 7.8 15.4 Goodwill 228.9 14.4 16.7 Total $ 359.2 $ 21.2 $ 33.5
Summary of fair value of separately identifiable intangible assets acquired	The following table summarizes the fair value of the separately identifiable intangible assets at the time of acquisition and the period over which each intangible asset will be amortized (in millions, except years): 2019 2018 2017 Mist HTBase Cyphort Weighted Amount Weighted Amount Weighted Amount Intangible assets: Existing technology 5 $ 81.0 4 $ 7.8 5 $ 15.4 Customer relationships 5 15.0 — — — — Trade name 5 6.0 — — — — Total intangible assets acquired $ 102.0 $ 7.8 $ 15.4

Cash Equivalents and Investme_2

Cash Equivalents and Investments (Tables)	12 Months Ended
	Dec. 31, 2019
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 December 31, 2019 and December 31, 2018 (in millions): As of December 31, 2019 As of December 31, 2018 Amortized Gross Unrealized Gross Unrealized Estimated Fair Amortized Gross Unrealized Gross Unrealized Estimated Fair Fixed income securities: Asset-backed securities $ 81.3 $ 0.1 $ — $ 81.4 $ 46.8 $ — $ (0.3 ) $ 46.5 Certificates of deposit 38.6 — — 38.6 152.9 — — 152.9 Commercial paper 168.2 — — 168.2 393.6 — — 393.6 Corporate debt securities 604.9 0.7 (0.1 ) 605.5 416.1 — (3.1 ) 413.0 Foreign government debt securities 11.4 — — 11.4 20.0 — (0.1 ) 19.9 Time deposits 226.3 — — 226.3 278.6 — — 278.6 U.S. government agency securities 89.0 — — 89.0 87.2 — (0.2 ) 87.0 U.S. government securities 394.3 0.3 (0.1 ) 394.5 811.8 — (0.5 ) 811.3 Total fixed income securities 1,614.0 1.1 (0.2 ) 1,614.9 2,207.0 — (4.2 ) 2,202.8 Privately-held debt and redeemable preferred stock securities 19.1 37.4 — 56.5 16.6 37.4 — 54.0 Total available-for-sale debt securities $ 1,633.1 $ 38.5 $ (0.2 ) $ 1,671.4 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8 Reported as: Cash equivalents $ 290.9 $ — $ — $ 290.9 $ 936.5 $ — $ — $ 936.5 Short-term investments 733.7 0.5 — 734.2 1,069.2 — (1.9 ) 1,067.3 Long-term investments 589.4 0.6 (0.2 ) 589.8 201.3 — (2.3 ) 199.0 Other long-term assets 19.1 37.4 — 56.5 16.6 37.4 — 54.0 Total $ 1,633.1 $ 38.5 $ (0.2 ) $ 1,671.4 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8
Maturities of fixed income securities	The following table presents the contractual maturities of the Company's total fixed income securities as of December 31, 2019 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,024.6 $ 1,025.1 Due between one and five years 589.4 589.8 Total $ 1,614.0 $ 1,614.9
Available-for-sale investments in an unrealized loss position	The following tables present the Company's total fixed income securities that were in an unrealized loss position as of December 31, 2019 and December 31, 2018 (in millions): 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 ) As of December 31, 2018 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 $ 3.1 $ — $ 43.0 $ (0.3 ) $ 46.1 $ (0.3 ) Corporate debt securities 72.6 (0.1 ) 330.7 (3.0 ) 403.3 (3.1 ) Foreign government debt securities 1.5 — 18.4 (0.1 ) 19.9 (0.1 ) U.S. government agency securities 2.0 — 45.2 (0.2 ) 47.2 (0.2 ) U.S. government securities 344.0 — 63.5 (0.5 ) 407.5 (0.5 ) Total fixed income securities $ 423.2 $ (0.1 ) $ 500.8 $ (4.1 ) $ 924.0 $ (4.2 )
Schedule of investments in equity securities	The following table presents the Company's investments in equity securities as of December 31, 2019 and 2018 (in millions): As of December 31, 2019 2018 Equity investments with readily determinable fair value Money market funds $ 446.4 $ 996.9 Mutual funds 26.8 24.3 Publicly-traded equity securities 3.8 2.8 Equity investments without readily determinable fair value 133.3 36.4 Total equity securities $ 610.3 $ 1,060.4 Reported as: Cash equivalents $ 442.3 $ 985.3 Short-term investments 3.8 2.8 Prepaid expenses and other current assets 4.1 10.9 Other long-term assets 160.1 61.4 Total $ 610.3 $ 1,060.4
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 Consolidated Balance Sheets as of December 31, 2019 and December 31, 2018 (in millions): As of December 31, 2019 2018 Cash and cash equivalents $ 1,215.8 $ 2,489.0 Restricted cash included in Prepaid expenses and other current assets 60.7 16.8 Total cash, cash equivalents, and restricted cash $ 1,276.5 $ 2,505.8

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
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 Consolidated Balance Sheets (in millions): Fair Value Measurements at Fair Value Measurements at Quoted Prices in Significant Other Significant Other Total Quoted Prices in Significant Other Significant Other Total Assets: Available-for-sale debt securities: Asset-backed securities $ — $ 81.4 $ — $ 81.4 $ — $ 46.5 $ — $ 46.5 Certificates of deposit — 38.6 — 38.6 — 152.9 — 152.9 Commercial paper — 168.2 — 168.2 — 393.6 — 393.6 Corporate debt securities — 605.5 — 605.5 — 413.0 — 413.0 Foreign government debt securities — 11.4 — 11.4 — 19.9 — 19.9 Time deposits — 226.3 — 226.3 — 278.6 — 278.6 U.S. government agency securities — 89.0 — 89.0 — 87.0 — 87.0 U.S. government securities 318.9 75.6 — 394.5 352.8 458.5 — 811.3 Privately-held debt and redeemable preferred stock securities — — 56.5 56.5 — — 54.0 54.0 Total available-for-sale debt securities 318.9 1,296.0 56.5 1,671.4 352.8 1,850.0 54.0 2,256.8 Equity securities: Money market funds 446.4 — — 446.4 996.9 — — 996.9 Mutual funds 26.8 — — 26.8 24.3 — — 24.3 Publicly-traded equity securities 3.8 — — 3.8 2.8 — — 2.8 Total equity securities 477.0 — — 477.0 1,024.0 — — 1,024.0 Derivative assets: Foreign exchange contracts — 2.5 — 2.5 — 5.3 — 5.3 Total derivative assets — 2.5 — 2.5 — 5.3 — 5.3 Total assets measured at fair value on a recurring basis $ 795.9 $ 1,298.5 $ 56.5 $ 2,150.9 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Liabilities: Derivative liabilities: Foreign exchange contracts $ — $ (6.8 ) $ — $ (6.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Interest rate swap contracts — (3.1 ) — (3.1 ) — — — — Total derivative liabilities — (9.9 ) — (9.9 ) — (7.1 ) — (7.1 ) Total liabilities measured at fair value on a recurring basis $ — $ (9.9 ) $ — $ (9.9 ) $ — $ (7.1 ) $ — $ (7.1 ) Total assets, reported as: Cash equivalents $ 442.3 $ 290.9 $ — $ 733.2 $ 1,025.2 $ 896.6 $ — $ 1,921.8 Short-term investments 188.8 549.2 — 738.0 297.5 772.6 — 1,070.1 Long-term investments 133.9 455.9 — 589.8 18.2 180.8 — 199.0 Prepaid expenses and other current assets 4.1 2.5 — 6.6 10.8 5.3 — 16.1 Other long-term assets 26.8 — 56.5 83.3 25.1 — 54.0 79.1 Total assets measured at fair value on a recurring basis $ 795.9 $ 1,298.5 $ 56.5 $ 2,150.9 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Fair Value Measurements at Fair Value Measurements at Quoted Prices in Significant Other Significant Other Total Quoted Prices in Significant Other Significant Other Total Total liabilities, reported as: Other accrued liabilities $ — $ (6.8 ) $ — $ (6.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Other long-term liabilities — (3.1 ) — (3.1 ) — — — — Total liabilities measured at fair value on a recurring basis $ — $ (9.9 ) $ — $ (9.9 ) $ — $ (7.1 ) $ — $ (7.1 )

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The notional amount of the Company's derivative instruments is summarized as follows (in millions): As of December 31, 2019 2018 Designated derivatives: Cash flow hedges $ 484.0 $ 497.7 Interest rate swap contracts 300.0 — Total designated derivatives $ 784.0 $ 497.7 Non-designated derivatives 162.9 158.7 Total $ 946.9 $ 656.4
Schedule of Derivative Liabilities at Fair Value	The fair value of derivative instruments on the Consolidated Balance Sheets was as follows: As of December 31, Balance Sheet Location 2019 2018 Derivative assets: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other current assets $ 2.2 $ 5.2 Foreign currency contracts as cash flow hedges Other long-term assets 0.3 — Total derivatives designated as hedging instruments $ 2.5 $ 5.2 Derivatives not designated as hedging instruments Other current assets — 0.1 Total derivative assets $ 2.5 $ 5.3 Derivative liabilities: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other accrued liabilities $ 6.6 $ 6.6 Interest rate swap designated as fair value hedges Other long-term liabilities 3.1 — Total derivatives designated as hedging instruments $ 9.7 $ 6.6 Derivatives not designated as hedging instruments Other accrued liabilities 0.2 0.5 Total derivative liabilities $ 9.9 $ 7.1
Schedule of Derivative Assets at Fair Value	The fair value of derivative instruments on the Consolidated Balance Sheets was as follows: As of December 31, Balance Sheet Location 2019 2018 Derivative assets: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other current assets $ 2.2 $ 5.2 Foreign currency contracts as cash flow hedges Other long-term assets 0.3 — Total derivatives designated as hedging instruments $ 2.5 $ 5.2 Derivatives not designated as hedging instruments Other current assets — 0.1 Total derivative assets $ 2.5 $ 5.3 Derivative liabilities: Derivatives designated as hedging instruments: Foreign currency contracts as cash flow hedges Other accrued liabilities $ 6.6 $ 6.6 Interest rate swap designated as fair value hedges Other long-term liabilities 3.1 — Total derivatives designated as hedging instruments $ 9.7 $ 6.6 Derivatives not designated as hedging instruments Other accrued liabilities 0.2 0.5 Total derivative liabilities $ 9.9 $ 7.1

Goodwill and Purchased Intang_2

Goodwill and Purchased Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The Company's goodwill activity was as follows (in millions): Total December 31, 2017 $ 3,096.2 Additions due to business combination 14.4 Other (*) (1.8 ) December 31, 2018 3,108.8 Additions due to business combination 228.3 December 31, 2019 $ 3,337.1 ________________________________ (*) Other primarily consists of certain purchase accounting adjustments related to the acquisition of Cyphort.
Schedule of Acquired Indefinite-Lived Intangible Assets by Major Class	The Company’s purchased intangible assets, net, were as follows (in millions): As of December 31, 2019 As of December 31, 2018 Gross Accumulated Accumulated Impairments and Net Gross Accumulated Accumulated Impairments and Net Finite-lived intangible assets: Technologies and patents $ 729.1 $ (564.0 ) $ (49.9 ) $ 115.2 $ 648.1 $ (534.0 ) $ (49.9 ) $ 64.2 Customer contracts, support agreements, and related relationships 98.6 (79.3 ) (2.8 ) 16.5 83.6 (75.5 ) (2.8 ) 5.3 Trade names and other 7.9 (2.8 ) — 5.1 2.0 (2.0 ) — — Total 835.6 (646.1 ) (52.7 ) 136.8 733.7 (611.5 ) (52.7 ) 69.5 Indefinite-lived intangible assets: IPR&D 49.0 — — 49.0 49.0 — — 49.0 Total purchased intangible assets $ 884.6 $ (646.1 ) $ (52.7 ) $ 185.8 $ 782.7 $ (611.5 ) $ (52.7 ) $ 118.5
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	The Company’s purchased intangible assets, net, were as follows (in millions): As of December 31, 2019 As of December 31, 2018 Gross Accumulated Accumulated Impairments and Net Gross Accumulated Accumulated Impairments and Net Finite-lived intangible assets: Technologies and patents $ 729.1 $ (564.0 ) $ (49.9 ) $ 115.2 $ 648.1 $ (534.0 ) $ (49.9 ) $ 64.2 Customer contracts, support agreements, and related relationships 98.6 (79.3 ) (2.8 ) 16.5 83.6 (75.5 ) (2.8 ) 5.3 Trade names and other 7.9 (2.8 ) — 5.1 2.0 (2.0 ) — — Total 835.6 (646.1 ) (52.7 ) 136.8 733.7 (611.5 ) (52.7 ) 69.5 Indefinite-lived intangible assets: IPR&D 49.0 — — 49.0 49.0 — — 49.0 Total purchased intangible assets $ 884.6 $ (646.1 ) $ (52.7 ) $ 185.8 $ 782.7 $ (611.5 ) $ (52.7 ) $ 118.5
Estimated Future Amortization Expense of Purchased Intangible Assets with Finite Lives	As of December 31, 2019 , the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions): Years Ending December 31, Amount 2020 $ 39.5 2021 35.3 2022 30.0 2023 25.7 2024 6.3 Thereafter — Total $ 136.8

Other Financial Information (Ta

Other Financial Information (Tables)	12 Months Ended
	Dec. 31, 2019
Other Financial Information [Abstract]
Inventories	Total inventory consisted of the following (in millions): As of December 31, 2019 2018 Production and service materials $ 69.0 $ 60.6 Finished goods 25.2 21.4 Inventory $ 94.2 $ 82.0 Reported as: Prepaid expenses and other current assets $ 90.6 $ 80.6 Other long-term assets 3.6 1.4 Total $ 94.2 $ 82.0
Property and equipment	Property and equipment, net, consisted of the following (in millions): As of December 31, 2019 2018 Computers and equipment $ 1,041.4 $ 1,100.0 Software 228.6 223.3 Leasehold improvements 216.9 235.2 Furniture and fixtures 48.3 48.6 Building and building improvements 255.0 254.3 Land and land improvements 243.5 243.2 Construction-in-process 12.9 19.5 Property and equipment, gross 2,046.6 2,124.1 Accumulated depreciation (1,215.7 ) (1,172.4 ) Property and equipment, net $ 830.9 $ 951.7
Outstanding notes receivable and deposit	Total outstanding notes receivable and deposit, net of issuance costs, reported within other long-term assets in the Consolidated Balance Sheets were as follows (in millions): As of December 31, 2019 2018 Pulse Note (including accumulated interest paid in kind) $ 78.9 $ 69.0 Contract manufacturer deposit (non-interest bearing) 46.0 23.9 Total $ 124.9 $ 92.9
Warranties	Changes in the Company’s warranty reserve were as follows (in millions): As of December 31, 2019 2018 Beginning balance $ 28.0 $ 27.4 Provisions made during the period, net 39.0 30.7 Actual costs incurred during the period (35.6 ) (30.1 ) Ending balance $ 31.4 $ 28.0
Deferred revenue	The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of December 31, 2019 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 $ 141.7 $ 118.6 $ 19.9 $ 3.2 Service (*) 1,103.6 706.7 328.3 68.6 Total $ 1,245.3 $ 825.3 $ 348.2 $ 71.8 ________________________________ (*) Represents unearned service revenue allocated to the performance obligations not delivered or partially delivered as of December 31, 2019. The unearned service revenue are comprised of deferred revenue and unbilled revenue. Details of the Company's deferred revenue, as reported in the Consolidated Balance Sheets, were as follows (in millions): As of December 31, 2019 2018 Deferred revenue: Undelivered product commitments and other product deferrals $ 141.7 $ 163.3 Deferred gross product revenue 141.7 163.3 Deferred cost of product revenue (9.1 ) (18.9 ) Deferred product revenue, net 132.6 144.4 Deferred gross service revenue 1,090.8 1,071.8 Deferred cost of service revenue — (2.6 ) Deferred service revenue, net 1,090.8 1,069.2 Total $ 1,223.4 $ 1,213.6 Reported as: Current $ 812.9 $ 829.3 Long-term 410.5 384.3 Total $ 1,223.4 $ 1,213.6
Other (expense) income, net	Other expense, net consisted of the following (in millions): Years Ended December 31, 2019 2018 2017 Interest income $ 79.1 $ 72.7 $ 53.0 Interest expense (88.7 ) (103.2 ) (101.2 ) Loss on extinguishment of debt (15.3 ) — — (Loss) gain on investments, net (3.8 ) (7.4 ) 14.6 Other 0.9 (1.6 ) (2.7 ) Other expense, net $ (27.8 ) $ (39.5 ) $ (36.3 )

Restructuring Charges (Tables)

Restructuring Charges (Tables)	12 Months Ended
	Dec. 31, 2019
Restructuring and Related Activities [Abstract]
Summary of Restructuring Charges	The following table presents restructuring charges included in the Consolidated Statements of Operations (in millions): Years Ended December 31, 2019 2018 2017 Severance $ 21.5 $ 8.3 $ 57.7 Facility consolidations 2.1 — — Contract terminations 11.7 (1.0 ) 7.9 Total $ 35.3 $ 7.3 $ 65.6 Reported as: Restructuring charges $ 35.3 $ 7.3 $ 65.6 Total $ 35.3 $ 7.3 $ 65.6
Schedule of Restructuring Liabilities	The following table provides a summary of changes in the restructuring liabilities associated with the 2019 Restructuring Plan and prior year plans (in millions): December 31, Charges/ (Benefits) Cash December 31, Severance $ 1.1 $ 21.5 $ (21.9 ) $ — $ 0.7 Facility consolidations — 2.1 (0.1 ) (2.0 ) — Contract terminations — 11.7 (11.5 ) (0.2 ) — Total $ 1.1 $ 35.3 $ (33.5 ) $ (2.2 ) $ 0.7

Debt and Financing (Tables)

Debt and Financing (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Instruments [Abstract]
Schedule of Long-term Debt	The following table summarizes the Company's total debt (in millions, except percentages): As of December 31, 2019 Issuance date Maturity Date Amount Effective Interest Rates Senior Notes ("Notes"): 4.500% fixed-rate notes (1) ("2024 Notes") March 2014 March 2024 $ 350.0 4.63 % 4.500% fixed-rate notes (1) ("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 (13.0 ) Hedge accounting fair value adjustments (2) (3.1 ) Total $ 1,683.9 ________________________________ (1) 2024 Notes issued in March 2014 and February 2016 form a single series and are fully fungible. (2) 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 6 , Derivative Instruments , for a discussion of the Company's interest rate swaps.
Schedule of Maturities of Long-term Debt	As of December 31, 2019 , the Company's aggregate debt maturities based on outstanding principal were as follows (in millions): Years Ending December 31, Amount 2020 $ — 2021 — 2022 — 2023 — 2024 500.0 Thereafter 1,200.0 Total $ 1,700.0

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Repurchase and retirement of common stock and net issuances	The following table summarizes dividends paid, stock repurchases and retirements under the Company's stock repurchase programs, and stock repurchases for tax withholdings (in millions, except per share amounts): Dividends Stock Repurchases Total Year Per Share Amount Shares Average price (1) Amount (2) Tax Withholding Amount Amount 2019 $ 0.76 $ 260.1 20.1 $ 25.36 $ 550.0 $ 5.0 $ 815.1 2018 $ 0.72 $ 249.3 29.3 $ 25.62 $ 750.0 $ 6.6 $ 1,005.9 2017 $ 0.40 $ 150.4 26.1 $ 27.61 $ 719.7 $ 6.1 $ 876.2 ________________________________ (1) $25.36 average price per share for 2019 excludes the $40.0 million covered by the forward contract discussed below. (2) 2019 and 2018 shares were repurchased under the 2018 Stock Repurchase Program. 2017 shares were repurchased under the 2014 Stock Repurchase Program.
Components of accumulated other comprehensive loss, net of taxes	The components of accumulated other comprehensive loss, net of related taxes, for the years ended December 31, 2019 , 2018 , and 2017 were as follows (in millions): Unrealized Gains/Losses on Available-for- Sale Debt Securities (1) Unrealized Gains/Losses on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2016 $ 16.6 $ (4.5 ) $ (49.4 ) $ (37.3 ) Other comprehensive income before reclassifications 4.5 15.7 19.0 39.2 Amount reclassified from accumulated other comprehensive loss (2.1 ) (5.2 ) — (7.3 ) Other comprehensive income, net 2.4 10.5 19.0 31.9 Balance as of December 31, 2017 $ 19.0 $ 6.0 $ (30.4 ) $ (5.4 ) Other comprehensive income (loss) before reclassifications 0.6 (6.4 ) (12.4 ) (18.2 ) Amount reclassified from accumulated other comprehensive income (loss) 0.9 (1.2 ) — (0.3 ) Other comprehensive income (loss), net 1.5 (7.6 ) (12.4 ) (18.5 ) Reclassification of tax effects upon adoption of ASU 2018-02 5.0 0.7 — 5.7 Balance as of December 31, 2018 $ 25.5 $ (0.9 ) $ (42.8 ) $ (18.2 ) Other comprehensive income (loss) before reclassifications 4.6 (8.9 ) (1.1 ) (5.4 ) Amount reclassified from accumulated other comprehensive income (loss) (0.4 ) 5.5 — 5.1 Other comprehensive income (loss), net 4.2 (3.4 ) (1.1 ) (0.3 ) Balance as of December 31, 2019 $ 29.7 $ (4.3 ) $ (43.9 ) $ (18.5 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive loss during the years ended December 31, 2019 , 2018 , and 2017 for realized gains on available-for-sale debt securities were not material, and were included in other expense, net, in the Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive loss during the years ended December 31, 2019 , 2018 , and 2017 for realized gains and losses on cash flow hedges were not material, and were included within cost of revenues, research and development, sales and marketing, and general and administrative in the Consolidated Statements of Operations.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Nonvested Share Activity	The following table summarizes the Company’s RSU, RSA, and PSA activity and related information as of and for the year ended December 31, 2019 (in millions, except per share amounts and years): Outstanding RSUs, RSAs, and PSAs (4) Number of Shares Weighted Average Grant-Date Fair Value per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance at December 31, 2018 17.4 $ 25.32 RSUs granted (1) 7.6 25.06 RSUs assumed upon the acquisition of Mist (1) 0.1 25.81 RSAs assumed upon the acquisition of Mist (1) 0.7 27.20 PSAs granted (2) 2.1 25.30 RSUs vested (3) (5.5 ) 25.99 RSAs vested (3) (0.2 ) 25.32 PSAs vested (3) (0.9 ) 25.13 RSUs canceled (2.3 ) 25.97 RSAs canceled (0.1 ) 27.65 PSAs canceled (1.4 ) 21.53 Balance at December 31, 2019 17.5 $ 25.30 1.1 $ 430.9 As of December 31, 2019 Vested and expected-to-vest RSUs, RSAs, and PSAs 16.2 $ 25.32 1.1 $ 399.2 ________________________________ (1) The weighted-average grant-date fair value of RSUs, RSAs, and PSAs granted and assumed or substituted during 2019 , 2018 , and 2017 was $25.26 , $25.33 , and $27.53 , respectively. 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. During 2019, the Company declared a quarterly cash dividend of $0.19 per share of common stock on January 29, 2019, April 25, 2019, July 25, 2019 and October 24, 2019. (2) Includes performance-based and market-based RSUs granted under the 2015 Plan according to their terms. The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to performance-based conditions that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 1.0 million shares. The aggregate number of shares subject to market-based conditions that would be issued if market criteria are achieved at target is 0.2 million shares. Depending on achievement of such market criteria, the range of shares that could be issued under these awards is zero to 0.4 million shares. (3) Total fair value of RSUs, RSAs, and PSAs vested during 2019 , 2018 , and 2017 was $170.0 million , $200.5 million , and $187.3 million , respectively. (4) 0.9 million shares of PSAs were modified in 2019, which relate to PSAs granted in 2018 and PSAs assumed by the Company in connection with acquisitions consummated in 2016. Compensation cost resulting from the modifications totaled $21.2 million to be recognized over the remaining terms of the modified awards.
Shares Available for Grant	The following table presents the stock activity and the total number of shares available for grant under the 2015 Plan (in millions): Number of Shares Balance as of December 31, 2018 21.9 Additional shares authorized 3.7 RSUs and PSAs granted (1) (15.5 ) RSUs and PSAs canceled (1)(2) 6.5 Balance as of December 31, 2019 16.6 ________________________________ (1) In May 2019, the 2015 Plan was amended, and the amendment removed the fungible share adjustment used to determine shares available for issuance. Under the original terms of the 2015 Plan, RSUs and PSAs with a per share or unit purchase price lower than 100% of the fair market value of the Company's common stock on the day of the grant were counted against shares authorized under the plan as two and one-tenth shares of common stock for each share subject to such award. Pursuant to the amendment, beginning on May 14, 2019, each share award granted under the 2015 Plan reduces the share reserve by one share and all share awards granted on May 14, 2019 and thereafter that are later forfeited, canceled or terminated are returned to the share reserve in the same manner. The number of shares subject to PSAs granted represents the maximum number of shares that may be issued pursuant to the award over its full term. (2) Canceled or expired options and canceled RSUs and PSAs under the 2006 Plan are no longer available for future grant under such plan; however, the number of shares available for grant under the 2015 Plan are increased by the amount of such canceled or expired options, RSUs or PSAs, as applicable, up to a maximum of 29.0 million additional shares of common stock, pursuant to the terms of the 2015 Plan.
Schedule Of Share-based Payment Award, Stock Options and Employee Stock Purchase Plan, Valuation Assumptions	The weighted-average assumptions used and the resulting estimates of fair value for ESPP and market-based RSUs were as follows: Years Ended December 31, 2019 2018 2017 ESPP: Volatility 27% 29% 25% Risk-free interest rate 2.1% 1.9% 0.9% Expected life (years) 1.2 1.2 0.5 Dividend yield 2.9% 2.7% 1.5% Weighted-average fair value per share $6.65 $6.93 $6.04 Market-based RSUs: Volatility 25% 28% 30% Risk-free interest rate 2.4% 2.4% 1.9% Dividend yield 2.8% 2.6% 1.4% Weighted-average fair value per share $27.32 $28.39 $19.30
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Company's Consolidated Statements of Operations (in millions): Years Ended December 31, 2019 2018 2017 Cost of revenues - Product $ 5.7 $ 6.3 $ 4.6 Cost of revenues - Service 17.3 18.0 17.5 Research and development 94.0 120.6 86.6 Sales and marketing 56.0 51.1 55.6 General and administrative 29.2 21.1 23.2 Total $ 202.2 $ 217.1 $ 187.5
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table summarizes share-based compensation expense by award type (in millions): Years Ended December 31, 2019 2018 2017 Stock options $ 7.7 $ 0.4 $ 0.5 RSUs, RSAs, and PSAs 176.5 198.2 171.3 ESPP 18.0 18.5 15.7 Total $ 202.2 $ 217.1 $ 187.5

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2019
Segment Reporting [Abstract]
Schedule of Financial Information by Segment	The following table presents net revenues by product and service (in millions): Years Ended December 31, 2019 2018 2017 Routing $ 1,623.2 $ 1,839.7 $ 2,189.5 Switching 901.0 934.4 963.4 Security 343.5 333.0 293.3 Total product 2,867.7 3,107.1 3,446.2 Total service 1,577.7 1,540.4 1,581.0 Total $ 4,445.4 $ 4,647.5 $ 5,027.2 The following table presents net revenues by customer vertical (in millions): Years Ended December 31, 2019 2018 2017 Cloud $ 1,059.8 $ 1,049.9 $ 1,310.7 Service Provider 1,827.8 2,066.7 2,319.4 Enterprise 1,557.8 1,530.9 1,397.1 Total $ 4,445.4 $ 4,647.5 $ 5,027.2
Schedule of 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): Years Ended December 31, 2019 2018 2017 Americas: United States $ 2,299.8 $ 2,339.1 $ 2,712.6 Other 218.2 202.1 234.6 Total Americas 2,518.0 2,541.2 2,947.2 Europe, Middle East, and Africa 1,215.3 1,290.8 1,195.8 Asia Pacific 712.1 815.5 884.2 Total $ 4,445.4 $ 4,647.5 $ 5,027.2
Schedule of Property and Equipment by Geographic Region	The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions): As of December 31, 2019 2018 United States $ 815.9 $ 941.7 International 200.8 128.5 Property and equipment, net and purchased intangible assets, net $ 1,016.7 $ 1,070.2

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Components of income before the provision for income taxes and noncontrolling interest	The components of pretax income are summarized as follows (in millions): Years Ended December 31, 2019 2018 2017 Domestic $ 296.2 $ 160.6 $ 474.2 Foreign 118.2 372.1 337.6 Total pretax income $ 414.4 $ 532.7 $ 811.8
Schedule of Components of Provision for Income Taxes	The provision (benefit) for income taxes is summarized as follows (in millions): Years Ended December 31, 2019 2018 2017 Current provision (benefit): Federal $ 6.2 $ (126.1 ) $ 594.3 States 14.4 9.0 13.9 Foreign 48.5 38.9 45.4 Total current provision (benefit) 69.1 (78.2 ) 653.6 Deferred provision (benefit): Federal 0.8 36.6 (128.7 ) States 2.8 2.2 (17.7 ) Foreign (3.3 ) 5.2 (1.6 ) Total deferred provision (benefit) 0.3 44.0 (148.0 ) Total provision (benefit) for income taxes $ 69.4 $ (34.2 ) $ 505.6
Schedule of Effective Income Tax Rate Reconciliation	The provision (benefit) for income taxes differs from the amount computed by applying the federal statutory rate of 21% for 2019, 21% for 2018, and 35% for 2017, respectively, to pretax income as follows (in millions): Years Ended December 31, 2019 2018 2017 Expected provision at statutory rate $ 87.0 $ 111.9 $ 284.1 State taxes, net of federal benefit 9.4 7.4 12.0 Foreign income at different tax rates 1.8 (12.8 ) (46.4 ) R&D tax credits (18.8 ) (22.1 ) (15.1 ) Share-based compensation 3.8 4.7 — Non-deductible compensation 3.3 1.9 1.6 Temporary differences not currently benefited 12.9 — — Recognition of previously unrecognized tax benefits (25.4 ) — — Lapses in federal statutes of limitations (7.5 ) (67.6 ) — Tax accounting method changes — (65.4 ) — Release of valuation allowance — — (1.7 ) Domestic production activities — — (12.4 ) Impact of the U.S. Tax Cuts and Jobs Act — 2.8 289.5 Other 2.9 5.0 (6.0 ) Total (benefit) provision for income taxes $ 69.4 $ (34.2 ) $ 505.6
Schedule of Deferred Tax Assets and Liabilities	Significant components of the Company's long-term deferred tax assets and deferred tax liabilities are as follows (in millions): As of December 31, 2019 2018 Deferred tax assets: Net operating loss carry-forwards $ 27.7 $ 12.9 Research and other credit carry-forwards 236.7 220.0 Deferred revenue 40.0 37.7 Share-based compensation 24.3 26.1 Cost sharing adjustment — 12.2 Reserves and accruals not currently deductible 55.8 62.7 Operating lease liabilities 48.3 — Other 12.0 13.2 Total deferred tax assets 444.8 384.8 Valuation allowance (249.4 ) (233.7 ) Deferred tax assets, net of valuation allowance 195.4 151.1 Deferred tax liabilities: Property and equipment basis differences (39.2 ) (40.6 ) Purchased intangibles (27.8 ) (13.7 ) Unremitted foreign earnings (23.7 ) (26.4 ) Deferred compensation and other (8.7 ) (8.9 ) Operating lease assets (41.1 ) — Total deferred tax liabilities (140.5 ) (89.6 ) Net deferred tax assets $ 54.9 $ 61.5
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows (in millions): Years Ended December 31, 2019 2018 2017 Balance at beginning of year $ 178.1 $ 264.5 $ 223.1 Tax positions related to current year: Additions 5.9 4.3 64.6 Tax positions related to prior years: Additions 0.8 12.7 1.8 Reductions (3.3 ) (33.8 ) (16.6 ) Settlements (22.5 ) (2.6 ) (4.0 ) Lapses in statutes of limitations (7.7 ) (67.0 ) (4.4 ) Balance at end of year $ 151.3 $ 178.1 $ 264.5

Net Income per Share (Tables)

Net Income per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of Calculation 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): Years Ended December 31, 2019 2018 2017 Numerator: Net income $ 345.0 $ 566.9 $ 306.2 Denominator: Weighted-average shares used to compute basic net income per share 343.2 349.0 377.7 Dilutive effect of employee stock awards 5.0 5.4 6.5 Weighted-average shares used to compute diluted net income per share 348.2 354.4 384.2 Net income per share: Basic $ 1.01 $ 1.62 $ 0.81 Diluted $ 0.99 $ 1.60 $ 0.80 Anti-dilutive shares 4.7 3.9 1.1

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Unrecorded Unconditional Purchase Obligations Disclosure	The following table summarizes the Company’s unconditional purchase obligations for each of the next five years and thereafter as of December 31, 2019 (in millions): Years Ending December 31, Unconditional Purchase Obligations 2020 $ 42.0 2021 28.8 2022 21.0 2023 13.7 2024 6.9 Thereafter 1.4 Total $ 113.8
Schedule of Lease Cost	The components of lease costs and other information related to leases were as follows (in millions, except years and percentages): December 31, 2019 Operating lease cost $ 50.3 Variable lease cost 12.6 Total lease cost $ 62.9 Operating cash outflows from operating leases $ 49.6 ROU assets obtained in exchange for new operating lease liabilities $ 14.0 Weighted average remaining lease term (years) 5.5 Weighted average discount rate 3.9 %
Schedule of Future Operating Lease Payments	As of December 31, 2019 , future operating lease payments for each of the next five years and thereafter is as follows (in millions): Years Ending December 31, Amount 2020 $ 49.3 2021 45.3 2022 36.3 2023 30.6 2024 26.8 Thereafter 37.7 Total lease payments 226.0 Less: interest (25.6 ) Total $ 200.4 Balance Sheet Information Other accrued liabilities 42.3 Long-term operating lease liabilities 158.1 Total $ 200.4
Other Commitments	The following table summarizes the Company’s purchase commitments for each of the next five years and thereafter as of December 31, 2019 (in millions): Years Ending December 31, Purchase Commitments 2020 $ 794.3 2021 230.7 2022 220.1 2023 226.4 Thereafter — Total $ 1,471.5
Schedule of Future Minimum Rental Payments for Operating Leases	As of December 31, 2018 , prior to the adoption of ASC 842, future minimum payments under non-cancelable operating and other lease arrangements for each of the next five years and thereafter were as follows (in millions): Leases Years Ending December 31, Operating Leases Other Lease Arrangement (*) 2019 $ 33.7 $ 13.1 2020 30.7 13.3 2021 24.3 13.6 2022 17.0 13.9 2023 14.3 14.2 Thereafter 26.3 32.9 Total $ 146.3 $ 101.0 _______________ (*) Represents a build-to-suit lease arrangement entered into in July 2015.

Selected Quarterly Financial _2

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Schedule of Selected Quarterly Financial Data (Unaudited)	The table below sets forth selected unaudited financial data for each quarter of the years ended December 31, 2019 and December 31, 2018 (in millions, except per share amounts): Year Ended December 31, 2019 Year Ended December 31, 2018 First Quarter Second Quarter Third Quarter Fourth Quarter First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues $ 1,001.7 $ 1,102.5 $ 1,133.1 $ 1,208.1 $ 1,082.6 $ 1,204.1 $ 1,179.8 $ 1,181.0 Gross margin 582.3 636.8 678.4 719.3 618.4 700.9 711.0 710.9 Income before income taxes 44.5 77.8 118.1 174.0 41.4 150.9 152.0 188.4 Net income (1) $ 31.1 $ 46.2 $ 99.3 $ 168.4 $ 34.4 $ 116.5 $ 223.8 $ 192.2 Net income per share: (2) Basic $ 0.09 $ 0.13 $ 0.29 $ 0.50 $ 0.10 $ 0.33 $ 0.65 $ 0.56 Diluted $ 0.09 $ 0.13 $ 0.29 $ 0.49 $ 0.10 $ 0.33 $ 0.64 $ 0.55 _______________ (1) Net income for the third and fourth quarters of 2018 include a lower statutory tax rate due to the Tax Act and tax benefits related to items unique to 2018. See Note 14, Income Taxes , for further discussion. (2) Net income per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period.

Significant Accounting Polici_4

Significant Accounting Policies - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)Customerleases	Dec. 31, 2018USD ($)Customer	Dec. 31, 2017USD ($)Customer
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Maturity of highly liquid investments	3 months
Warranty period for hardware products (in years)	1 year
Warranty period for software (in days)	90 days
Advertising expense | $	$ 14.6	$ 20	$ 19.9
More than likely percentage of being realized upon settlement, tax benefit	50.00%
Liability for unrecognized tax benefits as current, period	1 year
Number of customers accounting for more than 10% of revenues | Customer	0	0	0
Number of finance leases | leases	0
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, estimated useful life	4 years
Revenue from contract with customers, terms of payment (in days)	30 days
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Intangible assets, estimated useful life	5 years
Revenue from contract with customers, terms of payment (in days)	90 days
Interest Rate Swap
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Expiration period	10 years

Significant Accounting Polici_5

Significant Accounting Policies Significant Accounting Policies - Property, Plant and Equipment, Useful Lives (Details)	12 Months Ended
	Dec. 31, 2019
Computers, equipment, and software | Minimum
Property and Equipment [Line Items]
Useful life	1 year 6 months
Computers, equipment, and software | Maximum
Property and Equipment [Line Items]
Useful life	7 years
Furniture and fixtures | Minimum
Property and Equipment [Line Items]
Useful life	5 years
Furniture and fixtures | Maximum
Property and Equipment [Line Items]
Useful life	7 years
Building and building improvements | Minimum
Property and Equipment [Line Items]
Useful life	7 years
Building and building improvements | Maximum
Property and Equipment [Line Items]
Useful life	40 years
Land improvements | Minimum
Property and Equipment [Line Items]
Useful life	10 years
Land improvements | Maximum
Property and Equipment [Line Items]
Useful life	40 years
Leasehold improvements | Maximum
Property and Equipment [Line Items]
Useful life	10 years

Significant Accounting Polici_6

Significant Accounting Policies - Cumulative Impact of Recently Adopted Accounting Standards (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets	$ 376.3	$ 266.7	$ 268.1
Property and equipment, net	830.9	908.8	951.7
Operating lease assets	169.7	192.5
Other long-term assets	514.6	404.8	403.5
Total assets	8,837.7	9,512.8	9,363.3
Other accrued liabilities	282.5	269.1	233.5
Long-term operating lease liabilities	158.1	185.5
Other long-term liabilities	58.1	53.1	119.8
Total liabilities	4,227.1	4,694.5	4,540.1
Accumulated deficit	$ (2,741.4)	(2,836.3)	$ (2,831.4)
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Prepaid expenses and other current assets		(1.4)
Property and equipment, net		(42.9)
Operating lease assets		192.5
Other long-term assets		1.3
Total assets		149.5
Other accrued liabilities		35.6
Long-term operating lease liabilities		185.5
Other long-term liabilities		(66.7)
Total liabilities		154.4
Accumulated deficit		$ (4.9)

Business Combinations - Narrati

Business Combinations - Narrative (Details) - USD ($)	Apr. 01, 2019	Dec. 07, 2018	Sep. 18, 2017	Apr. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Acquisition related costs					$ 16,600,000	$ 4,400,000	$ 2,100,000
Mist Systems, Inc.
Business Acquisition [Line Items]
Voting interest acquired	100.00%
Consideration transferred	$ 359,200,000
Payments to acquire business	354,500,000
Consideration transferred, share based payments	$ 4,600,000
Share-based compensation assumed, fair value				$ 38,500,000
Fair value of pre-existing debt		$ 1,600,000
HTBase
Business Acquisition [Line Items]
Voting interest acquired		100.00%
Payments to acquire business		$ 19,600,000
Share-based awards assumed, fair value		$ 3,800,000
Cyphort
Business Acquisition [Line Items]
Voting interest acquired			100.00%
Payments to acquire business			$ 33,500,000
Share-based awards assumed, fair value			$ 3,800,000

Business Combinations - Purchas

Business Combinations - Purchase Price Allocation (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Mist Systems, Inc.
Business Acquisition [Line Items]
Net tangible assets acquired/(liabilities) assumed	$ 28.3
Intangible assets	102
Goodwill	228.9
Total	$ 359.2
HTBase
Business Acquisition [Line Items]
Net tangible assets acquired/(liabilities) assumed		$ (1)
Intangible assets		7.8
Goodwill		14.4
Total		$ 21.2
Cyphort
Business Acquisition [Line Items]
Net tangible assets acquired/(liabilities) assumed			$ 1.4
Intangible assets			15.4
Goodwill			16.7
Total			$ 33.5

Business Combinations - Intangi

Business Combinations - Intangible Assets Acquired (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Mist Systems, Inc.
Business Acquisition [Line Items]
Total intangible assets acquired	$ 102
Mist Systems, Inc. | Existing technology
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	5 years
Total intangible assets acquired	$ 81
Mist Systems, Inc. | Customer relationships
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	5 years
Total intangible assets acquired	$ 15
Mist Systems, Inc. | Trade name
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	5 years
Total intangible assets acquired	$ 6
HTBase
Business Acquisition [Line Items]
Total intangible assets acquired		$ 7.8
HTBase | Existing technology
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)		4 years
Total intangible assets acquired		$ 7.8
HTBase | Customer relationships
Business Acquisition [Line Items]
Total intangible assets acquired		0
HTBase | Trade name
Business Acquisition [Line Items]
Total intangible assets acquired		$ 0
Cyphort
Business Acquisition [Line Items]
Total intangible assets acquired			$ 15.4
Cyphort | Existing technology
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)			5 years
Total intangible assets acquired			$ 15.4
Cyphort | Customer relationships
Business Acquisition [Line Items]
Total intangible assets acquired			0
Cyphort | Trade name
Business Acquisition [Line Items]
Total intangible assets acquired			$ 0

Cash Equivalents and Investme_3

Cash Equivalents and Investments - Available for Sale Debt Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale debt securities:
Amortized Cost	$ 1,633.1	$ 2,223.6
Gross Unrealized Gains	38.5	37.4
Gross Unrealized Losses	(0.2)	(4.2)
Estimated Fair Value	1,671.4	2,256.8
Cash equivalents
Available-for-sale debt securities:
Amortized Cost	290.9	936.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	290.9	936.5
Short-term investments
Available-for-sale debt securities:
Amortized Cost	733.7	1,069.2
Gross Unrealized Gains	0.5	0
Gross Unrealized Losses	0	(1.9)
Estimated Fair Value	734.2	1,067.3
Long-term investments
Available-for-sale debt securities:
Amortized Cost	589.4	201.3
Gross Unrealized Gains	0.6	0
Gross Unrealized Losses	(0.2)	(2.3)
Estimated Fair Value	589.8	199
Other long-term assets
Available-for-sale debt securities:
Amortized Cost	19.1	16.6
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0	0
Estimated Fair Value	56.5	54
Asset-backed securities
Available-for-sale debt securities:
Amortized Cost	81.3	46.8
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	0	(0.3)
Estimated Fair Value	81.4	46.5
Certificates of deposit
Available-for-sale debt securities:
Amortized Cost	38.6	152.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	38.6	152.9
Commercial paper
Available-for-sale debt securities:
Amortized Cost	168.2	393.6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	168.2	393.6
Corporate debt securities
Available-for-sale debt securities:
Amortized Cost	604.9	416.1
Gross Unrealized Gains	0.7	0
Gross Unrealized Losses	(0.1)	(3.1)
Estimated Fair Value	605.5	413
Foreign government debt securities
Available-for-sale debt securities:
Amortized Cost	11.4	20
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(0.1)
Estimated Fair Value	11.4	19.9
Time deposits
Available-for-sale debt securities:
Amortized Cost	226.3	278.6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	226.3	278.6
U.S. government agency securities
Available-for-sale debt securities:
Amortized Cost	89	87.2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(0.2)
Estimated Fair Value	89	87
U.S. government securities
Available-for-sale debt securities:
Amortized Cost	394.3	811.8
Gross Unrealized Gains	0.3	0
Gross Unrealized Losses	(0.1)	(0.5)
Estimated Fair Value	394.5	811.3
Total fixed income securities
Available-for-sale debt securities:
Amortized Cost	1,614	2,207
Gross Unrealized Gains	1.1	0
Gross Unrealized Losses	(0.2)	(4.2)
Estimated Fair Value	1,614.9	2,202.8
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Amortized Cost	19.1	16.6
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 56.5	$ 54

Cash Equivalents and Investme_4

Cash Equivalents and Investments - Maturities of Available for Sale Investments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost
Amortized Cost	$ 1,633.1	$ 2,223.6
Estimated Fair Value
Total	1,671.4	2,256.8
Fixed Income Securities
Amortized Cost
Due in less than one year	1,024.6
Due between one and five years	589.4
Amortized Cost	1,614	2,207
Estimated Fair Value
Due in less than one year	1,025.1
Due between one and five years	589.8
Total	$ 1,614.9	$ 2,202.8

Cash Equivalents and Investme_5

Cash Equivalents and Investments - Unrealized Loss Position on Fixed Income Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Fair Value
Less than 12 Months	$ 259.8	$ 423.2
12 Months or Greater	11.3	500.8
Total	271.1	924
Unrealized Loss
Less than 12 Months	(0.2)	(0.1)
12 Months or Greater	0	(4.1)
Total	(0.2)	(4.2)
Asset-backed securities
Fair Value
Less than 12 Months	21.6	3.1
12 Months or Greater	5.2	43
Total	26.8	46.1
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	0	(0.3)
Total	0	(0.3)
Corporate debt securities
Fair Value
Less than 12 Months	142.6	72.6
12 Months or Greater	2.1	330.7
Total	144.7	403.3
Unrealized Loss
Less than 12 Months	(0.1)	(0.1)
12 Months or Greater	0	(3)
Total	(0.1)	(3.1)
Foreign government debt securities
Fair Value
Less than 12 Months	4	1.5
12 Months or Greater	4	18.4
Total	8	19.9
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	0	(0.1)
Total	0	(0.1)
U.S. government agency securities
Fair Value
Less than 12 Months	20	2
12 Months or Greater	0	45.2
Total	20	47.2
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	0	(0.2)
Total	0	(0.2)
U.S. government securities
Fair Value
Less than 12 Months	71.6	344
12 Months or Greater	0	63.5
Total	71.6	407.5
Unrealized Loss
Less than 12 Months	(0.1)	0
12 Months or Greater	0	(0.5)
Total	$ (0.1)	$ (0.5)

Cash Equivalents and Investme_6

Cash Equivalents and Investments - Narrative (Details)	12 Months Ended
	Dec. 31, 2019USD ($)Investment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Oct. 31, 2019USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Total investments In unrealized loss position | Investment	179
OTTI, associated with credit losses	$ 0
Available-for-sale debt securities, gross realized gain	0	$ 0	$ 0
Available-for-sale debt securities, gross realized losses	0	0	0
Equity ownership, cost method				$ 89,900,000
Equity investments, unrealized gains	0	0	0
Equity investments, unrealized losses	0	0	0
Restricted cash and investments	91,600,000
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	64,600,000
Other long-term assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	27,000,000
Debt Securities
Restricted Cash and Cash Equivalents Items [Line Items]
OTTI, associated with credit losses	$ 0	$ 0	$ 0
Privately-held company
Restricted Cash and Cash Equivalents Items [Line Items]
Ownership interest, percentage				13.70%

Cash Equivalents and Investme_7

Cash Equivalents and Investments - Equity Securities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments without readily determinable fair value	$ 133.3	$ 36.4
Total equity securities	610.3	1,060.4
Cash equivalents
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	442.3	985.3
Short-term investments
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	3.8	2.8
Prepaid expenses and other current assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	4.1	10.9
Other long-term assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	160.1	61.4
Money market funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	446.4	996.9
Mutual funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	26.8	24.3
Publicly-traded equity securities
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	$ 3.8	$ 2.8

Cash Equivalents and Investme_8

Cash Equivalents and Investments Cash Equivalents and Investments - Restricted Cash and Investments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 1,215.8	$ 2,489
Total cash, cash equivalents, and restricted cash	1,276.5	2,505.8	$ 2,059.1	$ 1,880.6
Prepaid expenses and other current assets
Cash and Cash Equivalents [Line Items]
Restricted cash	$ 60.7	$ 16.8

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale debt securities:
Debt securities	$ 1,671.4	$ 2,256.8
Derivative assets:
Foreign exchange contracts	2.5	5.3
Cash equivalents
Available-for-sale debt securities:
Debt securities	290.9	936.5
Short-term investments
Available-for-sale debt securities:
Debt securities	734.2	1,067.3
Long-term investments
Available-for-sale debt securities:
Debt securities	589.8	199
Asset-backed securities
Available-for-sale debt securities:
Debt securities	81.4	46.5
Certificates of deposit
Available-for-sale debt securities:
Debt securities	38.6	152.9
Commercial paper
Available-for-sale debt securities:
Debt securities	168.2	393.6
Corporate debt securities
Available-for-sale debt securities:
Debt securities	605.5	413
Foreign government debt securities
Available-for-sale debt securities:
Debt securities	11.4	19.9
Time deposits
Available-for-sale debt securities:
Debt securities	226.3	278.6
U.S. government agency securities
Available-for-sale debt securities:
Debt securities	89	87
U.S. government securities
Available-for-sale debt securities:
Debt securities	394.5	811.3
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Debt securities	56.5	54
Money market funds
Equity securities:
Equity securities	446.4	996.9
Publicly-traded equity securities
Equity securities:
Equity securities	3.8	2.8
Fair Value, Measurements, Recurring
Available-for-sale debt securities:
Debt securities	1,671.4	2,256.8
Equity securities:
Equity securities	477	1,024
Derivative assets:
Foreign exchange contracts	2.5	5.3
Total assets measured at fair value on a recurring basis	2,150.9	3,286.1
Derivative liabilities:
Foreign exchange contracts	(9.9)	(7.1)
Liability measured at non-recurring basis	(9.9)	(7.1)
Fair Value, Measurements, Recurring | Cash equivalents
Derivative assets:
Total assets measured at fair value on a recurring basis	733.2	1,921.8
Fair Value, Measurements, Recurring | Short-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	738	1,070.1
Fair Value, Measurements, Recurring | Long-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	589.8	199
Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Derivative assets:
Total assets measured at fair value on a recurring basis	6.6	16.1
Fair Value, Measurements, Recurring | Other long-term assets
Derivative assets:
Total assets measured at fair value on a recurring basis	83.3	79.1
Fair Value, Measurements, Recurring | Other accrued liabilities
Derivative liabilities:
Liability measured at non-recurring basis	(6.8)	(7.1)
Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative liabilities:
Liability measured at non-recurring basis	(3.1)	0
Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	2.5	5.3
Derivative liabilities:
Foreign exchange contracts	(6.8)	(7.1)
Fair Value, Measurements, Recurring | Interest Rate Swap
Derivative liabilities:
Foreign exchange contracts	(3.1)	0
Fair Value, Measurements, Recurring | Asset-backed securities
Available-for-sale debt securities:
Debt securities	81.4	46.5
Fair Value, Measurements, Recurring | Certificates of deposit
Available-for-sale debt securities:
Debt securities	38.6	152.9
Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale debt securities:
Debt securities	168.2	393.6
Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale debt securities:
Debt securities	605.5	413
Fair Value, Measurements, Recurring | Foreign government debt securities
Available-for-sale debt securities:
Debt securities	11.4	19.9
Fair Value, Measurements, Recurring | Time deposits
Available-for-sale debt securities:
Debt securities	226.3	278.6
Fair Value, Measurements, Recurring | U.S. government agency securities
Available-for-sale debt securities:
Debt securities	89	87
Fair Value, Measurements, Recurring | U.S. government securities
Available-for-sale debt securities:
Debt securities	394.5	811.3
Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Debt securities	56.5	54
Fair Value, Measurements, Recurring | Money market funds
Equity securities:
Equity securities	446.4	996.9
Fair Value, Measurements, Recurring | Mutual funds
Equity securities:
Equity securities	26.8	24.3
Fair Value, Measurements, Recurring | Publicly-traded equity securities
Equity securities:
Equity securities	3.8	2.8
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring
Available-for-sale debt securities:
Debt securities	318.9	352.8
Equity securities:
Equity securities	477	1,024
Derivative assets:
Foreign exchange contracts	0	0
Total assets measured at fair value on a recurring basis	795.9	1,376.8
Derivative liabilities:
Foreign exchange contracts	0	0
Liability measured at non-recurring basis	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Cash equivalents
Derivative assets:
Total assets measured at fair value on a recurring basis	442.3	1,025.2
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Short-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	188.8	297.5
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Long-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	133.9	18.2
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Derivative assets:
Total assets measured at fair value on a recurring basis	4.1	10.8
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Other long-term assets
Derivative assets:
Total assets measured at fair value on a recurring basis	26.8	25.1
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Other accrued liabilities
Derivative liabilities:
Liability measured at non-recurring basis	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative liabilities:
Liability measured at non-recurring basis	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	0	0
Derivative liabilities:
Foreign exchange contracts	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Interest Rate Swap
Derivative liabilities:
Foreign exchange contracts	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Asset-backed securities
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Certificates of deposit
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Foreign government debt securities
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Time deposits
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | U.S. government agency securities
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | U.S. government securities
Available-for-sale debt securities:
Debt securities	318.9	352.8
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Debt securities	0	0
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Money market funds
Equity securities:
Equity securities	446.4	996.9
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Mutual funds
Equity securities:
Equity securities	26.8	24.3
Quoted Prices in Active Markets For Identical Assets (Level 1) | Fair Value, Measurements, Recurring | Publicly-traded equity securities
Equity securities:
Equity securities	3.8	2.8
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring
Available-for-sale debt securities:
Debt securities	1,296	1,850
Equity securities:
Equity securities	0	0
Derivative assets:
Foreign exchange contracts	2.5	5.3
Total assets measured at fair value on a recurring basis	1,298.5	1,855.3
Derivative liabilities:
Foreign exchange contracts	(9.9)	(7.1)
Liability measured at non-recurring basis	(9.9)	(7.1)
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Cash equivalents
Derivative assets:
Total assets measured at fair value on a recurring basis	290.9	896.6
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Short-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	549.2	772.6
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Long-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	455.9	180.8
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Derivative assets:
Total assets measured at fair value on a recurring basis	2.5	5.3
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Other long-term assets
Derivative assets:
Total assets measured at fair value on a recurring basis	0	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Other accrued liabilities
Derivative liabilities:
Liability measured at non-recurring basis	(6.8)	(7.1)
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative liabilities:
Liability measured at non-recurring basis	(3.1)	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	2.5	5.3
Derivative liabilities:
Foreign exchange contracts	(6.8)	(7.1)
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Interest Rate Swap
Derivative liabilities:
Foreign exchange contracts	(3.1)	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Asset-backed securities
Available-for-sale debt securities:
Debt securities	81.4	46.5
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Certificates of deposit
Available-for-sale debt securities:
Debt securities	38.6	152.9
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale debt securities:
Debt securities	168.2	393.6
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale debt securities:
Debt securities	605.5	413
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Foreign government debt securities
Available-for-sale debt securities:
Debt securities	11.4	19.9
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Time deposits
Available-for-sale debt securities:
Debt securities	226.3	278.6
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. government agency securities
Available-for-sale debt securities:
Debt securities	89	87
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | U.S. government securities
Available-for-sale debt securities:
Debt securities	75.6	458.5
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Money market funds
Equity securities:
Equity securities	0	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Mutual funds
Equity securities:
Equity securities	0	0
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring | Publicly-traded equity securities
Equity securities:
Equity securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring
Available-for-sale debt securities:
Debt securities	56.5	54
Equity securities:
Equity securities	0	0
Derivative assets:
Foreign exchange contracts	0	0
Total assets measured at fair value on a recurring basis	56.5	54
Derivative liabilities:
Foreign exchange contracts	0	0
Liability measured at non-recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Cash equivalents
Derivative assets:
Total assets measured at fair value on a recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Short-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Long-term investments
Derivative assets:
Total assets measured at fair value on a recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Prepaid expenses and other current assets
Derivative assets:
Total assets measured at fair value on a recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Other long-term assets
Derivative assets:
Total assets measured at fair value on a recurring basis	56.5	54
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Other accrued liabilities
Derivative liabilities:
Liability measured at non-recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Other long-term liabilities
Derivative liabilities:
Liability measured at non-recurring basis	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	0	0
Derivative liabilities:
Foreign exchange contracts	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Interest Rate Swap
Derivative liabilities:
Foreign exchange contracts	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Asset-backed securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Certificates of deposit
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Foreign government debt securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Time deposits
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | U.S. government agency securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | U.S. government securities
Available-for-sale debt securities:
Debt securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Debt securities	56.5	54
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Money market funds
Equity securities:
Equity securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Mutual funds
Equity securities:
Equity securities	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring | Publicly-traded equity securities
Equity securities:
Equity securities	$ 0	$ 0

Fair Value Measurements Fair Va

Fair Value Measurements Fair Value Measurement - Narrative (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and intangible impairment	$ 0		$ 0	$ 0
Contract manufacturer deposit (non-interest bearing)	46,000,000	$ 46,000,000	23,900,000
Junos Pulse
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pulse Note (including accumulated interest paid in kind)	78,900,000	78,900,000	69,000,000
Significant Other Observable Remaining Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt, fair value	1,852,100,000	1,852,100,000	2,158,700,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	9,900,000	9,900,000	7,100,000
Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	0	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	9,900,000	9,900,000	7,100,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	$ 0	0	$ 0
Privately-held debt and redeemable preferred stock securities | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on investments		$ 0

Derivative Instruments - Notion

Derivative Instruments - Notional Amount (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Notional amount	$ 946.9	$ 656.4
Designated as hedge
Derivatives, Fair Value [Line Items]
Notional amount	784	497.7
Non-designated derivatives
Derivatives, Fair Value [Line Items]
Notional amount	162.9	158.7
Foreign exchange contracts | Cash flow hedges | Designated as hedge
Derivatives, Fair Value [Line Items]
Notional amount	484	497.7
Interest Rate Swap | Fair Value Hedging | Designated as hedge
Derivatives, Fair Value [Line Items]
Notional amount	$ 300	$ 0

Derivative Instruments Derivati

Derivative Instruments Derivative Instruments - Fair Value of Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative asset, fair value	$ 2.5	$ 5.3
Derivative liability, fair value	9.9	7.1
Designated as hedge
Derivative [Line Items]
Derivative asset, fair value	2.5	5.2
Derivative liability, fair value	9.7	6.6
Other current assets | Non-designated derivatives
Derivative [Line Items]
Derivative asset, fair value	0	0.1
Other accrued liabilities | Non-designated derivatives
Derivative [Line Items]
Derivative liability, fair value	0.2	0.5
Cash flow hedges | Other current assets | Designated as hedge | Foreign exchange contracts
Derivative [Line Items]
Derivative asset, fair value	2.2	5.2
Cash flow hedges | Other long-term assets | Designated as hedge | Foreign exchange contracts
Derivative [Line Items]
Derivative asset, fair value	0.3	0
Cash flow hedges | Other accrued liabilities | Designated as hedge | Foreign exchange contracts
Derivative [Line Items]
Derivative liability, fair value	6.6	6.6
Fair Value Hedging | Other long-term liabilities | Designated as hedge | Interest Rate Swap
Derivative [Line Items]
Derivative liability, fair value	$ 3.1	$ 0

Derivative Instruments - Narrat

Derivative Instruments - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Notional amount	$ 946.9	$ 656.4
Foreign exchange contracts | Cost of revenues and operating expenses
Derivatives, Fair Value [Line Items]
Gain (loss) reclassified	(3.8)
Changes in fair value of non-designated derivatives	3.6	7.6	$ 1.8
Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	(6.3)
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion		(8.7)	20.2
Cash flow hedges | Foreign exchange contracts | Cost of revenues and operating expenses
Derivatives, Fair Value [Line Items]
Gain (loss) reclassified		0.9	$ 7.6
Designated as hedge
Derivatives, Fair Value [Line Items]
Notional amount	$ 784	497.7
Designated as hedge | Cash flow hedges
Derivatives, Fair Value [Line Items]
Maturities of derivatives	24 months
Losses expected to be reclassified into earnings within the next 12 months	$ 4.4
Designated as hedge | Cash flow hedges | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Notional amount	484	497.7
Non-designated derivatives
Derivatives, Fair Value [Line Items]
Notional amount	$ 162.9	$ 158.7
Minimum | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Maturities of derivatives	1 month
Maximum | Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Maturities of derivatives	4 months

Goodwill and Purchased Intang_3

Goodwill and Purchased Intangible Assets - GoodwillRollforward (Details)	12 Months Ended
	Dec. 31, 2019USD ($)Reportable_Segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 3,108,800,000	$ 3,096,200,000
Additions due to business combination	228,300,000	14,400,000
Other		(1,800,000)
Goodwill, end of period	$ 3,337,100,000	3,108,800,000	$ 3,096,200,000
Number of reporting units | Reportable_Segment	3
Goodwill impairment	$ 0	$ 0	$ 0

Goodwill and Purchased Intang_4

Goodwill and Purchased Intangible Assets - Purchased Intangible Assets, Net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Purchased Intangible Assets [Line Items]
Gross	$ 835,600,000	$ 733,700,000
Accumulated amortization	(646,100,000)	(611,500,000)
Impairment and other charges	(52,700,000)	(52,700,000)
Net	136,800,000	69,500,000
Total purchased intangible assets, gross	884,600,000	782,700,000
Purchased intangible assets, net	185,800,000	118,500,000
Amortization of intangible assets	34,700,000	17,400,000	$ 17,500,000
Impairment of intangible assets	0	0	$ 0
IPR&D
Purchased Intangible Assets [Line Items]
Indefinite-lived intangible assets:	49,000,000	49,000,000
Technologies and patents
Purchased Intangible Assets [Line Items]
Gross	729,100,000	648,100,000
Accumulated amortization	(564,000,000)	(534,000,000)
Impairment and other charges	(49,900,000)	(49,900,000)
Net	115,200,000	64,200,000
Customer contracts, support agreements, and related relationships
Purchased Intangible Assets [Line Items]
Gross	98,600,000	83,600,000
Accumulated amortization	(79,300,000)	(75,500,000)
Impairment and other charges	(2,800,000)	(2,800,000)
Net	16,500,000	5,300,000
Trade name
Purchased Intangible Assets [Line Items]
Gross	7,900,000	2,000,000
Accumulated amortization	(2,800,000)	(2,000,000)
Impairment and other charges	0	0
Net	$ 5,100,000	$ 0

Goodwill and Purchased Intang_5

Goodwill and Purchased Intangible Assets - Estimated Future Amortization Expense Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2020	$ 39.5
2021	35.3
2022	30
2023	25.7
2024	6.3
Thereafter	0
Net	$ 136.8	$ 69.5

Other Financial Information - I

Other Financial Information - Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Other Financial Information [Abstract]
Production materials	$ 69	$ 60.6
Finished goods	25.2	21.4
Schedule Of Inventory [Line Items]
Inventory	94.2	82
Prepaid expenses and other current assets
Schedule Of Inventory [Line Items]
Inventory	90.6	80.6
Other long-term assets
Schedule Of Inventory [Line Items]
Inventory	$ 3.6	$ 1.4

Other Financial Information - P

Other Financial Information - Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Property and Equipment [Line Items]
Property and equipment, gross	$ 2,046.6	$ 2,124.1
Accumulated depreciation	(1,215.7)	(1,172.4)
Property and equipment, net	830.9	951.7		$ 908.8
Depreciation expense	184	193.2	$ 202.8
Computers and equipment
Property and Equipment [Line Items]
Property and equipment, gross	1,041.4	1,100
Software
Property and Equipment [Line Items]
Property and equipment, gross	228.6	223.3
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	216.9	235.2
Furniture and fixtures
Property and Equipment [Line Items]
Property and equipment, gross	48.3	48.6
Building and building improvements
Property and Equipment [Line Items]
Property and equipment, gross	255	254.3
Land and land improvements
Property and Equipment [Line Items]
Property and equipment, gross	243.5	243.2
Construction-in-process
Property and Equipment [Line Items]
Property and equipment, gross	$ 12.9	$ 19.5

Other Financial Information - N

Other Financial Information - Note Receivable and Deposit (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contract manufacturer deposit (non-interest bearing)	$ 46	$ 23.9
Total	124.9	92.9
Junos Pulse
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pulse Note (including accumulated interest paid in kind)	$ 78.9	$ 69

Other Financial Information -_2

Other Financial Information - Notes Receivable and Deposit, Revenue, Deferred Commissions Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2014
Disaggregation of Revenue [Line Items]
Proceeds from pulse note receivable	$ 0	$ 0	$ 75,000,000
Non-interest bearing deposit to contract manufacturer	23,600,000	25,000,000
Non-interest bearing deposit to contract manufacturer, unamortized discount	$ 2,600,000	$ 1,100,000
Non-interest bearing deposit to contract manufacturer, imputed interest rate	5.00%	4.80%
Deposit assets	$ 48,600,000
Impairment charge, notes receivable	0	$ 0	0
Deferred commission	24,100,000	33,700,000
Amortization of deferred commission	130,900,000	144,200,000
Impairment loss	0
Product
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	68,600,000
Service
Disaggregation of Revenue [Line Items]
Contract with customer, liability, revenue recognized	706,800,000
Junos Pulse
Disaggregation of Revenue [Line Items]
Promissory note				$ 125,000,000
Proceeds from pulse note receivable			75,000,000
Interest income	$ 10,400,000	$ 8,400,000	$ 8,300,000

Other Financial Information - W

Other Financial Information - Warranties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Warranty Reserve [Roll Forward]
Beginning balance	$ 28	$ 27.4
Provisions made during the period, net	39	30.7
Actual costs incurred during the period	(35.6)	(30.1)
Ending balance	$ 31.4	$ 28

Other Financial Information - D

Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred revenue:
Deferred revenue	$ 1,223.4	$ 1,213.6
Reported as:
Current deferred revenue	812.9	829.3
Long-term deferred revenue	410.5	384.3
Undelivered Product Commitments and Other Product Deferrals [Member]
Deferred revenue:
Deferred revenue, gross	141.7	163.3
Product
Deferred revenue:
Deferred revenue, gross	141.7	163.3
Deferred cost	(9.1)	(18.9)
Deferred revenue	132.6	144.4
Service
Deferred revenue:
Deferred revenue, gross	1,090.8	1,071.8
Deferred cost	0	(2.6)
Deferred revenue	$ 1,090.8	$ 1,069.2

Other Financial Information - R

Other Financial Information - Revenue, Remaining Performance Obligation (Details) $ in Millions	Dec. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 825.3
Revenue recognition expected by period, satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 348.2
Revenue recognition expected by period, satisfaction period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 71.8
Revenue recognition expected by period, satisfaction period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 1,245.3
Product | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 118.6
Revenue recognition expected by period, satisfaction period	1 year
Product | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 19.9
Revenue recognition expected by period, satisfaction period	2 years
Product | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 3.2
Revenue recognition expected by period, satisfaction period
Product | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 141.7
Service | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 706.7
Revenue recognition expected by period, satisfaction period	1 year
Service | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 328.3
Revenue recognition expected by period, satisfaction period	2 years
Service | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 68.6
Revenue recognition expected by period, satisfaction period
Service | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 1,103.6

Other Financial Information - O

Other Financial Information - Other Expense, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Financial Information [Abstract]
Interest income	$ 79.1	$ 72.7	$ 53
Interest expense	(88.7)	(103.2)	(101.2)
Loss on extinguishment of debt	(15.3)	0	0
(Loss) gain on investments, net	(3.8)	(7.4)	14.6
Other	0.9	(1.6)	(2.7)
Other expense, net	$ (27.8)	$ (39.5)	$ (36.3)

Restructuring Charges - Include

Restructuring Charges - Included in Cost of Revenues and Restructuring and Other Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges (benefits)	$ 35.3	$ 7.3	$ 65.6
Restructuring charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges (benefits)	35.3	7.3	65.6
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges (benefits)	21.5	8.3	57.7
Facility consolidations
Restructuring Cost and Reserve [Line Items]
Restructuring charges (benefits)	2.1	0	0
Contract terminations
Restructuring Cost and Reserve [Line Items]
Restructuring charges (benefits)	$ 11.7	$ (1)	$ 7.9

Restructuring Charges - Roll-fo

Restructuring Charges - Roll-forward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Charges/ (Benefits)	$ 35.3	$ 7.3	$ 65.6
2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	35.3
Cash Payments	(33.5)
Other	(2.2)
Restructuring liability, ending balance	0.7	1.1
2019 Restructuring Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	21.5
Cash Payments	(21.9)
Other	0
Restructuring liability, ending balance	0.7	1.1
2019 Restructuring Plan | Facility consolidations
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0
Charges/ (Benefits)	2.1
Cash Payments	(0.1)
Other	(2)
Restructuring liability, ending balance	0	0
2019 Restructuring Plan | Contract terminations
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0
Charges/ (Benefits)	11.7
Cash Payments	(11.5)
Other	(0.2)
Restructuring liability, ending balance	$ 0	$ 0

Debt and Financing - Schedule o

Debt and Financing - Schedule of Debt (Details) - USD ($) $ in Millions	Dec. 31, 2019	Aug. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt	$ 1,700
Unaccreted discount and debt issuance costs	(13)
Hedge accounting fair value adjustment	(3.1)
Total	1,683.9
Notional amount	$ 946.9		$ 656.4
4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Stated interest rate	4.50%
4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Stated interest rate	4.50%
4.350% fixed-rate notes (2025 Notes)
Debt Instrument [Line Items]
Stated interest rate	4.35%
3.750% fixed-rate notes (2029 Notes)
Debt Instrument [Line Items]
Stated interest rate	3.75%
5.950% fixed-rate notes (2041 Notes)
Debt Instrument [Line Items]
Stated interest rate	5.95%
Senior Notes
Debt Instrument [Line Items]
Long-term debt	$ 1,700
Senior Notes | 4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 350
Effective interest rate	4.63%
Senior Notes | 4.500% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 150
Effective interest rate	4.87%
Senior Notes | 4.350% fixed-rate notes (2025 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 300
Effective interest rate	4.47%
Senior Notes | 3.750% fixed-rate notes (2029 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 500
Stated interest rate		3.75%
Effective interest rate	3.86%
Senior Notes | 5.950% fixed-rate notes (2041 Notes)
Debt Instrument [Line Items]
Long-term debt	$ 400
Effective interest rate	6.03%
Designated as hedge
Debt Instrument [Line Items]
Notional amount	$ 784		497.7
Fair Value Hedging | Interest Rate Swap | Designated as hedge
Debt Instrument [Line Items]
Notional amount	$ 300		$ 0

Debt and Financing - Schedule_2

Debt and Financing - Schedule of Aggregate Debt Maturities (Details) $ in Millions	Dec. 31, 2019USD ($)
Debt Instruments [Abstract]
2020	$ 0
2021	0
2022	0
2023	0
2024	500
Thereafter	1,200
Total	$ 1,700

Debt and Financing - Narrative

Debt and Financing - Narrative (Details)	1 Months Ended	2 Months Ended	12 Months Ended
	Apr. 30, 2019USD ($)extension_option	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Aug. 31, 2019USD ($)
Debt Instrument [Line Items]
Repayment of debt			$ 950,000,000	$ 0	$ 0
Loss on extinguishment of debt			15,300,000	0	0
Sale of receivables			64,000,000	122,800,000	169,400,000
Proceeds from sale and collection of receivables			69,700,000	123,200,000	$ 169,300,000
Receivables from sale of receivables			5,300,000	$ 17,200,000
Cash received from financing provider			$ 0
Minimum
Debt Instrument [Line Items]
Number of days due from receivable			1 day
Maximum
Debt Instrument [Line Items]
Number of days due from receivable			90 days
3.750% fixed-rate notes (2029 Notes)
Debt Instrument [Line Items]
Stated interest rate			3.75%
4.350% fixed-rate notes (2025 Notes)
Debt Instrument [Line Items]
Stated interest rate			4.35%
Senior Notes | 3.750% fixed-rate notes (2029 Notes)
Debt Instrument [Line Items]
Principal amount						$ 500,000,000
Stated interest rate						3.75%
Redemption period prior to maturity			3 months
Senior Notes | 3.750% fixed-rate notes (2029 Notes) | US Treasury (UST) Interest Rate
Debt Instrument [Line Items]
Redemption price, basis spread on discount rate			35.00%
Senior Notes | Fixed Rate Note Due 2020 And Fixed Rate Note Due 2021
Debt Instrument [Line Items]
Repayment of debt		$ 600,000,000
Loss on extinguishment of debt		$ 15,300,000
Senior Notes | 3.300% fixed-rate notes (2020 Notes)
Debt Instrument [Line Items]
Stated interest rate						3.30%
Senior Notes | 4.350% fixed-rate notes (2025 Notes)
Debt Instrument [Line Items]
Redemption period prior to maturity			3 months
Senior Notes | 4.350% fixed-rate notes (2025 Notes) | US Treasury (UST) Interest Rate
Debt Instrument [Line Items]
Redemption price, basis spread on discount rate			37.50%
Senior Notes | 4.600% fixed-rate notes (2024 Notes)
Debt Instrument [Line Items]
Stated interest rate						4.60%
Senior Notes | Fixed Rate Note Due 2025 And Fixed Rate Note Due 2029
Debt Instrument [Line Items]
Debt instrument, redemption price, percent			100.00%
Repurchase price percentage related to change in control			101.00%
Line of Credit
Debt Instrument [Line Items]
Amounts outstanding			$ 0
Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 500,000,000
Debt, term	5 years
Additional borrowing capacity	$ 200,000,000
Extension options | extension_option	2
Maturity extension option period	1 year
Amounts outstanding			$ 0
Maximum leverage ratio	3
Maximum leverage ratio, if acquisition is consummated	3.5
Interest coverage ratio	3
Line of Credit | Revolving Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Line of Credit | Revolving Credit Facility | Minimum | Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	0.91%
Line of Credit | Revolving Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.375%
Line of Credit | Revolving Credit Facility | Maximum | Eurodollar
Debt Instrument [Line Items]
Basis spread on variable rate	1.375%
Variable Rate Component, Federal Funds | Line of Credit | Revolving Credit Facility | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Variable Rate Component, ICE Benchmark Administration Settlement Rate | Line of Credit | Revolving Credit Facility | ICE Benchmark Administration Settlement Rate
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%

Equity - Stock Repurchase Activ

Equity - Stock Repurchase Activities (Details) $ / shares in Units, shares in Millions	Dec. 26, 2019$ / shares	Oct. 28, 2019USD ($)$ / sharesshares	Oct. 24, 2019$ / shares	Sep. 25, 2019$ / shares	Jul. 25, 2019$ / shares	Jun. 24, 2019$ / shares	Apr. 25, 2019$ / shares	Mar. 22, 2019$ / shares	Jan. 29, 2019$ / shares	Oct. 31, 2019USD ($)	Apr. 30, 2019USD ($)	Feb. 28, 2018USD ($)	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2019USD ($)Dividend$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Jan. 31, 2018USD ($)
Dividends
Per Share (in dollars per share) | $ / shares	$ 0.19			$ 0.19		$ 0.19		$ 0.19					$ 0.19		$ 0.76	$ 0.72	$ 0.40
Amount															$ 260,100,000	$ 249,300,000	$ 150,400,000
Stock Repurchase Program
Number of quarterly cash dividends declared | Dividend															4
Cash dividends declared per share of common stock (in dollars per share) | $ / shares			$ 0.19		$ 0.19		$ 0.19		$ 0.19
Payment to repurchase stock															$ 554,900,000	$ 756,600,000	$ 725,800,000
Stock repurchased under ASR, market price (in dollars per share) | $ / shares		$ 25.15
Remaining forward contract, value															$ 40,000,000
Stock Repurchase Program 2018
Stock Repurchase Program
Shares (in shares) | shares															20.1	29.3
Average price per share (in dollars per share) | $ / shares															$ 25.36	$ 25.62
Amount		$ 160,000,000											$ 50,000,000		$ 550,000,000	$ 750,000,000
Tax Withholding Amount															5,000,000	6,600,000
Dividends and stock repurchase program, total amount															815,100,000	$ 1,005,900,000
Stock repurchase program, authorized amount										$ 3,000,000,000								$ 2,000,000,000
Stock repurchase program, increased amount										$ 1,000,000,000
Stock repurchased (in Shares) | shares													2.1
Stock repurchased average cost (in usd per share) | $ / shares													$ 23.63
Stock repurchase program, authorized funds remaining													$ 1,700,000,000	$ 1,700,000,000	$ 1,700,000,000
Stock Repurchase Program 2014
Stock Repurchase Program
Shares (in shares) | shares																	26.1
Average price per share (in dollars per share) | $ / shares																	$ 27.61
Amount																	$ 719,700,000
Tax Withholding Amount																	6,100,000
Dividends and stock repurchase program, total amount																	$ 876,200,000
Accelerated Share Repurchase Program
Stock Repurchase Program
Shares (in shares) | shares		6.4												11.6	29.3
Average price per share (in dollars per share) | $ / shares														$ 25.79	$ 25.62
Stock repurchase program, authorized amount		$ 200,000,000
Payment to repurchase stock		$ 200,000,000									$ 300,000,000	$ 750,000,000

Equity - Accumulated Other Comp

Equity - Accumulated Other Comprehensive Income, Net of Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net		$ 0
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	$ (18.2)	(5.4)	$ (37.3)
Other comprehensive income (loss) before reclassifications	(5.4)	(18.2)	39.2
Amount reclassified from accumulated other comprehensive income (loss)	5.1	(0.3)	(7.3)
Other comprehensive income (loss), net	(0.3)	(18.5)	31.9
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net		5.7
Balance at end of period	(18.5)	(18.2)	(5.4)
Unrealized Gains on Available-for- Sale Securities
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	25.5	19	16.6
Other comprehensive income (loss) before reclassifications	4.6	0.6	4.5
Amount reclassified from accumulated other comprehensive income (loss)	(0.4)	0.9	(2.1)
Other comprehensive income (loss), net	4.2	1.5	2.4
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net		5
Balance at end of period	29.7	25.5	19
Unrealized Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	(0.9)	6	(4.5)
Other comprehensive income (loss) before reclassifications	(8.9)	(6.4)	15.7
Amount reclassified from accumulated other comprehensive income (loss)	5.5	(1.2)	(5.2)
Other comprehensive income (loss), net	(3.4)	(7.6)	10.5
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net		0.7
Balance at end of period	(4.3)	(0.9)	6
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Balance at beginning of period	(42.8)	(30.4)	(49.4)
Other comprehensive income (loss) before reclassifications	(1.1)	(12.4)	19
Amount reclassified from accumulated other comprehensive income (loss)	0	0	0
Other comprehensive income (loss), net	(1.1)	(12.4)	19
Reclassification of tax effects upon adoption of ASU 2018-02 (Topic 220), net		0
Balance at end of period	$ (43.9)	$ (42.8)	$ (30.4)

Employee Benefit Plans - Equity

Employee Benefit Plans - Equity Incentive Plans (Details)	Nov. 06, 2017period	May 31, 2019shares	May 31, 2017shares	Dec. 31, 2019USD ($)shares	Dec. 31, 2018shares	May 19, 2015shares
Share-Based Compensation Plans
ESPP, offering period (in months)	24 months
ESPP, number of offering period | period	4
ESPP, purchase period (in months)	6 months
ESPP, purchase price (in percentage)	85.00%
Common stock - shares issued (in shares)				335,900,000	346,400,000
Common shares outstanding from equity awards through acquisition (in shares)				3,800,000
Various Acquisitions
Share-Based Compensation Plans
Common shares outstanding from equity awards through acquisition (in shares)				2,200,000
Equity Incentive Plan 2015
Share-Based Compensation Plans
Number of shares authorized (in shares)						38,000,000
Additional shares authorized (in shares)		3,700,000	23,000,000	3,700,000
Number of shares available for future issuance (in shares)				16,600,000	21,900,000
Equity Incentive Plan 1996 and 2006
Share-Based Compensation Plans
Maximum additional shares expired, unexercised, canceled (in shares)		29,000,000
Number of shares available for future issuance (in shares)				0
Equity Incentive Plan 2015 and 2006
Share-Based Compensation Plans
Aggregate shares subject to outstanding equity awards				13,700,000
Employee Stock Purchase Plan 2008
Share-Based Compensation Plans
Number of shares authorized (in shares)				35,000,000
Number of shares available for future issuance (in shares)				6,300,000
Discount on share purchase price for purchases made under ESPP				15.00%
Periodic payroll deduction - percentage of base salary				10.00%
ESPP individual purchase limits (in shares)				6,000
Period for share purchases under ESPP				12 months
ESPP individual purchase limits | $				$ 25,000
Period for ESPP purchases				1 year
Common stock - shares issued (in shares)				28,700,000

Employee Benefit Plans - RSU, R

Employee Benefit Plans - RSU, RSA, and PSA Activities (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 24, 2019	Jul. 25, 2019	Apr. 25, 2019	Jan. 29, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted Average Grant-Date Fair Value per Share
Cash dividends declared per share of common stock (in dollars per share)	$ 0.19	$ 0.19	$ 0.19	$ 0.19
Fair value of RSUs, RSAs and PSAs					$ 170	$ 200.5	$ 187.3
Restricted Stock Units (RSU) and Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period					3 years
Restricted Stock Units (RSUs)
Number of Shares
Granted (in shares)					7,600,000
Substituted in acquisitions (in shares)					100,000
Vested (in shares)					(5,500,000)
Canceled (in shares)					(2,300,000)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)					$ 25.06
Substituted in acquisitions (in dollars per share)					25.81
Vested (in dollars per share)					25.99
Canceled (in dollars per share)					25.97
Balance at end of period (in dollars per share)					$ 25.26
Number of performance shares (in shares)					200,000
Restricted Stock Units (RSUs) | Minimum
Weighted Average Grant-Date Fair Value per Share
Number of performance shares (in shares)					0
Restricted Stock Units (RSUs) | Maximum
Weighted Average Grant-Date Fair Value per Share
Number of performance shares (in shares)					400,000
Performance Shares (PSAs)
Number of Shares
Granted (in shares)					2,100,000
Vested (in shares)					(900,000)
Canceled (in shares)					(1,400,000)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)					$ 25.30
Vested (in dollars per share)					25.13
Canceled (in dollars per share)					21.53
Balance at end of period (in dollars per share)					$ 27.53
Number of performance shares (in shares)					700,000
Number of modified shares (in shares)					900,000
Compensation cost from modifications					$ 21.2
Performance Shares (PSAs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period					2 years
Weighted Average Grant-Date Fair Value per Share
Number of performance shares (in shares)					0
Performance Shares (PSAs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period					3 years
Weighted Average Grant-Date Fair Value per Share
Number of performance shares (in shares)					1,000,000
RSA
Number of Shares
Substituted in acquisitions (in shares)					700,000
Vested (in shares)					(200,000)
Canceled (in shares)					(100,000)
Weighted Average Grant-Date Fair Value per Share
Substituted in acquisitions (in dollars per share)					$ 27.20
Vested (in dollars per share)					25.32
Canceled (in dollars per share)					27.65
Balance at end of period (in dollars per share)					$ 25.33
RSUs, RSAs, and PSAs
Number of Shares
Balance at beginning of period (in shares)					17,400,000
Balance at end of period (in shares)					17,500,000	17,400,000
Weighted Average Grant-Date Fair Value per Share
Balance at beginning of period (in dollars per share)					$ 25.32
Balance at end of period (in dollars per share)					$ 25.30	$ 25.32
Weighted Average Remaining Contractual Term (In Years)					1 year 1 month 6 days
Aggregate Intrinsic Value					$ 430.9
Vested and expected-to-vest RSUs and PSAs, number of shares at (in shares)					16,200,000
Vested and expected-to-vest RSUs and PSA, grant date fair value (in dollars per share)					$ 25.32
Options vested and expected to vest, weighted average remaining contractual term					1 year 1 month 6 days
Vested and expected-to-vest RSUs and PSA, aggregate intrinsic value					$ 399.2

Employee Benefit Plans - Shares

Employee Benefit Plans - Shares Available For Grant (Details) - Equity Incentive Plan 2015 - shares shares in Millions	1 Months Ended		12 Months Ended
	May 31, 2019	May 31, 2017	Dec. 31, 2019
Shares Available For Grant
Balance as of beginning of period (in shares)			21.9
Additional shares authorized (in shares)	3.7	23	3.7
RSUs and PSAs granted (in shares)			(15.5)
RSUs and PSAs canceled (in shares)			6.5
Balance as of end of period (in shares)			16.6

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Purchase Plan and Valuation Assumptions (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Stock Purchase Plan
Estimates of Fair Value
Volatility	27.00%	29.00%	25.00%
Risk-free interest rate	2.10%	1.90%	0.90%
Expected life (years)	1 year 2 months 12 days	1 year 2 months 12 days	6 months
Dividend yield	2.90%	2.70%	1.50%
Weighted-average fair value per share (in dollars per share)	$ 6.65	$ 6.93	$ 6.04
Market-based RSUs
Estimates of Fair Value
Volatility	25.00%	28.00%	30.00%
Risk-free interest rate	2.40%	2.40%	1.90%
Dividend yield	2.80%	2.60%	1.40%
Weighted-average fair value per share (in dollars per share)	$ 27.32	$ 28.39	$ 19.30
Employee Stock Purchase Plan 2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares purchased through ESPP (in shares)	2.4	2.5	2.7
Average exercise price of shares purchased through ESPP (in dollars per share)	$ 22.04	$ 22.31	$ 20.83

Employee Benefit Plans - Share-

Employee Benefit Plans - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 202.2	$ 217.1	$ 187.5
Stock options
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	7.7	0.4	0.5
RSUs, RSAs, and PSAs
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	176.5	198.2	171.3
ESPP
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	18	18.5	15.7
Cost of revenues - Product
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	5.7	6.3	4.6
Cost of revenues - Service
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	17.3	18	17.5
Research and development
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	94	120.6	86.6
Sales and marketing
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	56	51.1	55.6
General and administrative
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 29.2	$ 21.1	$ 23.2

Employee Benefit Plans - Shar_2

Employee Benefit Plans - Share-Based Compensation Expense Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company recognized tax benefits on total stock-based compensation expense	$ 29.6	$ 33.8	$ 29.1
Tax benefit realized related to awards vested or exercised during the period	30.6	$ 38.9	$ 64.1
Unrecognized compensation cost	$ 280.7
RSUs, RSAs, and PSAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period that unrecognized compensation cost will be recognized	1 year 7 months 6 days

Employee Benefit Plans - 401(k)

Employee Benefit Plans - 401(k) plan, Deferred Compensation Plan and Non-US Pension Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Benefit Textuals [Abstract]
Employee contribution matched	30.00%
Matching contributions to plan	$ 20.2	$ 20.2	$ 21.1
NQDC
Employee Benefit Textuals [Abstract]
Deferred compensation liability	26.8	24.3
Investment	26.8	24.3
Prepaid expenses and other current assets | NQDC
Employee Benefit Textuals [Abstract]
Investment	4.1	3.6
Other long-term assets | NQDC
Employee Benefit Textuals [Abstract]
Investment	22.7	20.7
Other accrued liabilities | NQDC
Employee Benefit Textuals [Abstract]
Deferred compensation liability	4.1	3.6
Other long-term liabilities | NQDC
Employee Benefit Textuals [Abstract]
Deferred compensation liability	$ 22.7	$ 20.7

Segments - Revenue (Details)

Segments - Revenue (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment									1
Net Revenues [Abstract]
Net revenues	$ 1,208.1	$ 1,133.1	$ 1,102.5	$ 1,001.7	$ 1,181	$ 1,179.8	$ 1,204.1	$ 1,082.6	$ 4,445.4	$ 4,647.5	$ 5,027.2
Routing
Net Revenues [Abstract]
Net revenues									1,623.2	1,839.7	2,189.5
Switching
Net Revenues [Abstract]
Net revenues									901	934.4	963.4
Security
Net Revenues [Abstract]
Net revenues									343.5	333	293.3
Product
Net Revenues [Abstract]
Net revenues									2,867.7	3,107.1	3,446.2
Service
Net Revenues [Abstract]
Net revenues									1,577.7	1,540.4	1,581
Cloud
Net Revenues [Abstract]
Net revenues									1,059.8	1,049.9	1,310.7
Service Provider
Net Revenues [Abstract]
Net revenues									1,827.8	2,066.7	2,319.4
Enterprise
Net Revenues [Abstract]
Net revenues									$ 1,557.8	$ 1,530.9	$ 1,397.1

Segments - Geographical (Detail

Segments - Geographical (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)Customer	Dec. 31, 2018USD ($)Customer	Dec. 31, 2017USD ($)Customer
Net Revenues by Geographic Region [Line Items]
Net revenues	$ 1,208.1	$ 1,133.1	$ 1,102.5	$ 1,001.7	$ 1,181	$ 1,179.8	$ 1,204.1	$ 1,082.6	$ 4,445.4	$ 4,647.5	$ 5,027.2
Property and equipment, net and purchased intangible assets, net	1,016.7				1,070.2				$ 1,016.7	$ 1,070.2
Number of customers accounting for more than 10% of revenues | Customer									0	0	0
Total Americas
Net Revenues by Geographic Region [Line Items]
Net revenues									$ 2,518	$ 2,541.2	$ 2,947.2
United States
Net Revenues by Geographic Region [Line Items]
Net revenues									2,299.8	2,339.1	2,712.6
Property and equipment, net and purchased intangible assets, net	815.9				941.7				815.9	941.7
Other
Net Revenues by Geographic Region [Line Items]
Net revenues									218.2	202.1	234.6
Europe, Middle East, and Africa
Net Revenues by Geographic Region [Line Items]
Net revenues									1,215.3	1,290.8	1,195.8
Asia Pacific
Net Revenues by Geographic Region [Line Items]
Net revenues									712.1	815.5	$ 884.2
International
Net Revenues by Geographic Region [Line Items]
Property and equipment, net and purchased intangible assets, net	$ 200.8				$ 128.5				$ 200.8	$ 128.5

Income Taxes - Components of In

Income Taxes - Components of Income Tax (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of income before provision for income taxes and noncontrolling interest
Domestic									$ 296.2	$ 160.6	$ 474.2
Foreign									118.2	372.1	337.6
Income before income taxes	$ 174	$ 118.1	$ 77.8	$ 44.5	$ 188.4	$ 152	$ 150.9	$ 41.4	414.4	532.7	811.8
Current provision (benefit):
Federal									6.2	(126.1)	594.3
States									14.4	9	13.9
Foreign									48.5	38.9	45.4
Total current provision (benefit)									69.1	(78.2)	653.6
Deferred provision (benefit):
Federal									0.8	36.6	(128.7)
States									2.8	2.2	(17.7)
Foreign									(3.3)	5.2	(1.6)
Total deferred provision (benefit)									0.3	44	(148)
Income tax reconciliation
Expected provision at 35% rate									87	111.9	284.1
State taxes, net of federal benefit									9.4	7.4	12
Foreign income at different tax rates									1.8	(12.8)	(46.4)
R&D tax credits									(18.8)	(22.1)	(15.1)
Share-based compensation									3.8	4.7	0
Non-deductible compensation									3.3	1.9	1.6
Temporary differences not currently benefited									12.9	0	0
Recognition of previously unrecognized tax benefits									25.4		0
Lapses in federal statutes of limitations									7.5	67.6	0
Tax accounting method changes									0	(65.4)	0
Release of valuation allowance									0	0	(1.7)
Domestic production activities									0	0	(12.4)
Impact of the U.S. Tax Cuts and Jobs Act									0	2.8	289.5
Other									2.9	5	(6)
Total provision (benefit) for income taxes									$ 69.4	(34.2)	$ 505.6
Product
Income tax reconciliation
Income tax benefit result of filing a change in accounting method										(33.2)
Service
Income tax reconciliation
Income tax benefit result of filing a change in accounting method										$ (33.2)

Income Taxes - Deferred Taxes (

Income Taxes - Deferred Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss carry-forwards	$ 27.7	$ 12.9
Research and other credit carry-forwards	236.7	220
Deferred revenue	40	37.7
Share-based compensation	24.3	26.1
Cost sharing adjustment	0	12.2
Reserves and accruals not currently deductible	55.8	62.7
Operating lease liabilities	48.3	0
Other	12	13.2
Total deferred tax assets	444.8	384.8
Valuation allowance	(249.4)	(233.7)
Deferred tax assets, net of valuation allowance	195.4	151.1
Deferred tax liabilities:
Property and equipment basis differences	(39.2)	(40.6)
Purchased intangibles	(27.8)	(13.7)
Unremitted foreign earnings	(23.7)	(26.4)
Deferred compensation and other	(8.7)	(8.9)
Operating lease assets	(41.1)	0
Total deferred tax liabilities	(140.5)	(89.6)
Net deferred tax assets	54.9	61.5
Valuation allowance	249.4	233.7
Increase (decrease) in DTA valuation allowance	15.7	$ 19.2
Undistributed earnings of foreign subsidiaries	35.8
Additional income tax expense related to undistributed earnings	7.1
Federal
Deferred tax liabilities:
Net operating loss carry-forwards	101.2
Tax credit carry-forwards	4.7
California
Deferred tax liabilities:
Net operating loss carry-forwards	134
Tax credit carry-forwards	262.5
California Deferred Tax Assets
Deferred tax assets:
Valuation allowance	(221.6)
Deferred tax liabilities:
Valuation allowance	221.6
Net operating loss carry-forwards	134
Massachusetts Deferred Tax Assets
Deferred tax assets:
Valuation allowance	(20.2)
Deferred tax liabilities:
Valuation allowance	20.2
Canadian Deferred Tax Assets
Deferred tax assets:
Valuation allowance	(3.1)
Deferred tax liabilities:
Valuation allowance	3.1
Capital Loss Carryforward
Deferred tax assets:
Valuation allowance	(4.5)
Deferred tax liabilities:
Valuation allowance	$ 4.5

Income Taxes - Income Tax Conti

Income Taxes - Income Tax Contingencies (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Contingency [Line Items]
Unrecognized tax benefits that would impact effective tax rate	$ 150.9	$ 150.9
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year		178.1	$ 264.5	$ 223.1
Current Year [Abstract]
Additions		5.9	4.3	64.6
Prior Years [Abstract]
Additions		0.8	12.7	1.8
Reductions in unrecognized tax benefits		(3.3)	(33.8)	(16.6)
Settlements		(22.5)	(2.6)	(4)
Lapses in statutes of limitations		(7.7)	(67)	(4.4)
Balance at end of year	151.3	151.3	178.1	264.5
Tax expense recognized for net interest and penalties in the Consolidated Statements of Operations		2.8	5.2	8.5
Previously unrecognized tax benefits, income tax examination	30.9	30.9
Income tax examination, interest and penalties	8.4
Other long-term liabilities
Prior Years [Abstract]
Interest and penalties accrued related to unrecognized tax benefits	$ 29.9	29.9	$ 33.8	$ 40.7
Minimum | State and Local Jurisdiction | California Franchise Tax Board
Prior Years [Abstract]
Reductions in unrecognized tax benefits		(9.6)
Maximum | State and Local Jurisdiction | California Franchise Tax Board
Prior Years [Abstract]
Reductions in unrecognized tax benefits		$ (24.6)

Net Income per Share (Details)

Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income	$ 168.4	$ 99.3	$ 46.2	$ 31.1	$ 192.2	$ 223.8	$ 116.5	$ 34.4	$ 345	$ 566.9	$ 306.2
Denominator:
Weighted-average shares used to compute basic net income per share									343.2	349	377.7
Dilutive effect of employee stock awards									5	5.4	6.5
Weighted-average shares used to compute diluted net income per share									348.2	354.4	384.2
Net income per share:
Basic (in dollars per share)	$ 0.50	$ 0.29	$ 0.13	$ 0.09	$ 0.56	$ 0.65	$ 0.33	$ 0.10	$ 1.01	$ 1.62	$ 0.81
Diluted (in dollars per share)	$ 0.49	$ 0.29	$ 0.13	$ 0.09	$ 0.55	$ 0.64	$ 0.33	$ 0.10	$ 0.99	$ 1.60	$ 0.80
Anti-dilutive shares excluded from computation of diluted earnings per share									4.7	3.9	1.1

Commitments and Contingencies -

Commitments and Contingencies - Commitments (Details) $ in Millions	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 42
2021	28.8
2022	21
2023	13.7
2024	6.9
Thereafter	1.4
Total	$ 113.8

Commitments and Contingencies_2

Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Guarantor Obligations [Line Items]
Minimum fixed fees payable	$ 113.8
Operating lease rent expense	42	$ 0	$ 0
Rent expense		39	39.3
Accrued estimated carrying charges	28.6
Long-term debt	1,683.9
Income taxes payable		245.2
Unrecognized tax benefits	151.3	178.1	$ 264.5	$ 223.1
Indemnification Agreement
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	9	11.9
Financing guarantees, bank guarantees, and standby letters of credit
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	30.6	$ 23.1
Master Service Agreement
Guarantor Obligations [Line Items]
Expected payment	300
Energy Services Agreement
Guarantor Obligations [Line Items]
Expected payment	$ 29
Energy services agreement duration	15 years
Facilities | Minimum
Guarantor Obligations [Line Items]
Lease term	1 year
Facilities | Maximum
Guarantor Obligations [Line Items]
Lease term	10 years
Equipment | Minimum
Guarantor Obligations [Line Items]
Lease term	1 year
Equipment | Maximum
Guarantor Obligations [Line Items]
Lease term	4 years
Other Lease Arrangement | Maximum
Guarantor Obligations [Line Items]
Lease term	10 years
Long-term Income Taxes
Guarantor Obligations [Line Items]
Unrecognized tax benefits	$ 127.4

Commitments and Contingencies_3

Commitments and Contingencies - Leases (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 50.3
Variable lease cost	12.6
Total lease cost	62.9
Operating cash outflows from operating leases	49.6
ROU assets obtained in exchange for new operating lease liabilities	$ 14
Weighted average remaining lease term (years)	5 years 6 months
Weighted average discount rate	3.90%

Commitments and Contingencies C

Commitments and Contingencies Commitments and Contingencies - Schedule of Future Minimum Lease Payments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
Commitments and Contingencies Disclosure [Abstract]
2020	$ 49.3
2021	45.3
2022	36.3
2023	30.6
2024	26.8
Thereafter	37.7
Total lease payments	226
Less: interest	(25.6)
Total	200.4
Other accrued liabilities	42.3
Long-term operating lease liabilities	$ 158.1	$ 185.5

Commitments and Contingencies_4

Commitments and Contingencies Commitments and Contingencies - Purchase Commitments (Details) $ in Millions	Dec. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 794.3
2021	230.7
2022	220.1
2023	226.4
Thereafter	0
Total	$ 1,471.5

Commitments and Contingencies_5

Commitments and Contingencies Commitments and Contingencies - Future Minimum Rental Payments (Details) $ in Millions	Dec. 31, 2018USD ($)
Operating Leases
2019	$ 33.7
2020	30.7
2021	24.3
2022	17
2023	14.3
Thereafter	26.3
Total	146.3
Other Lease Arrangement
2019	13.1
2020	13.3
2021	13.6
2022	13.9
2023	14.2
Thereafter	32.9
Total	$ 101

Selected Quarterly Financial _3

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Selected Quarterly Financial Information [Abstract]
Net revenues	$ 1,208.1	$ 1,133.1	$ 1,102.5	$ 1,001.7	$ 1,181	$ 1,179.8	$ 1,204.1	$ 1,082.6	$ 4,445.4	$ 4,647.5	$ 5,027.2
Gross margin	719.3	678.4	636.8	582.3	710.9	711	700.9	618.4	2,616.8	2,741.2	3,072.1
Income before income taxes	174	118.1	77.8	44.5	188.4	152	150.9	41.4	414.4	532.7	811.8
Net income (loss)	$ 168.4	$ 99.3	$ 46.2	$ 31.1	$ 192.2	$ 223.8	$ 116.5	$ 34.4	$ 345	$ 566.9	$ 306.2
Net income per share:
Basic (in dollars per share)	$ 0.50	$ 0.29	$ 0.13	$ 0.09	$ 0.56	$ 0.65	$ 0.33	$ 0.10	$ 1.01	$ 1.62	$ 0.81
Diluted (in dollars per share)	$ 0.49	$ 0.29	$ 0.13	$ 0.09	$ 0.55	$ 0.64	$ 0.33	$ 0.10	$ 0.99	$ 1.60	$ 0.80

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, shares in Millions

Jan. 27, 2020

Oct. 28, 2019

Oct. 24, 2019

Jul. 25, 2019

Apr. 25, 2019

Jan. 29, 2019

Feb. 20, 2020

Mar. 31, 2020

Dec. 31, 2019

Dec. 31, 2019

Dec. 31, 2019

Dec. 31, 2018

Mar. 31, 2020

Oct. 31, 2019

Jan. 31, 2018

Subsequent Event [Line Items]

Cash dividends declared per share of common stock (in dollars per share)

$ 0.19

$ 0.19

$ 0.19

$ 0.19

Subsequent Event

Subsequent Event [Line Items]

Cash dividends declared per share of common stock (in dollars per share)

$ 0.20

Shares repurchased (in shares)

6.7

Stock repurchased and retired during period, value

$ 179,800,000

Price paid per share

$ 23.68

Stock repurchased (in Shares)

7.6

Accelerated Share Repurchase Program

Subsequent Event [Line Items]

Shares repurchased (in shares)

6.4

11.6

29.3

Stock repurchase program, authorized amount

$ 200,000,000

Stock Repurchase Program 2018

Subsequent Event [Line Items]

Shares repurchased (in shares)

20.1

29.3

Stock repurchased and retired during period, value

$ 160,000,000

$ 50,000,000

$ 550,000,000

$ 750,000,000

Stock repurchased (in Shares)

2.1

Stock repurchase program, authorized amount

$ 3,000,000,000

$ 2,000,000,000

Stock Repurchase Program 2018 | Subsequent Event

Subsequent Event [Line Items]

Stock repurchase program, authorized amount

$ 1,500,000,000

Forecast | Subsequent Event

Subsequent Event [Line Items]

Stock repurchased and retired (in usd per share)

$ 24.44

Forecast | Accelerated Share Repurchase Program | Subsequent Event

Subsequent Event [Line Items]

Shares repurchased (in shares)

1.8

8.2

Schedule II- Valuation and Qu_2

Schedule II- Valuation and Qualifying Account (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 4.9	$ 5.7	$ 7.6
Charged to (Reversed from) Costs and Expenses	1.7	(0.8)	(2)
Write-offs, Net of Recoveries	(1.1)	0	0.1
Balance at End of Year	5.5	4.9	5.7
Sales return reserve	5.5	5.7	7.6		$ 5.7
Sales Return Reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	32.7	55.2	71.4
Balance at beginning of year, excluding reduction of cumulative effect adjustment, topic 606					44.5
Charged as a Reduction in Revenues	59.5	70.7	25
Charged to Other Accounts	0	0	65.9
Used	(67.4)	(82.5)	(107.1)
Balance at End of Year	24.8	32.7	55.2
Sales return reserve	$ 32.7	$ 55.2	$ 55.2		$ 55.2
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09 | Sales Return Reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Sales return reserve				$ (10.7)

Uncategorized Items - jnpr-10k2

Label	Element	Value
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 324,700,000
Accounting Standards Update 2014-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	324,700,000
Accounting Standards Update 2016-02 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(4,800,000)
Accounting Standards Update 2016-02 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0
Accounting Standards Update 2016-02 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(4,800,000)
Accounting Standards Update 2016-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	3,800,000
Accounting Standards Update 2016-09 [Member] | Common Stock Including Additional Paid in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	12,800,000
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(9,000,000)
Accounting Standards Update 2017-12 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	100,000
Accounting Standards Update 2017-12 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 100,000