Juniper Networks (JNPR) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 03, 2019
Document and Entity Information [Abstract]
Entity Registrant Name	JUNIPER NETWORKS INC
Entity Central Index Key	0001043604
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		344,325,417

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Total net revenues	$ 1,001.7	$ 1,082.6
Cost of revenues:
Total cost of revenues	419.4	464.2
Gross margin	582.3	618.4
Operating expenses:
Research and development	227.6	269.4
Sales and marketing	228.5	239.4
General and administrative	68.2	56
Restructuring charges (benefits)	15.3	(1.9)
Total operating expenses	539.6	562.9
Operating income	42.7	55.5
Other income (expense), net	1.8	(14.1)
Income before income taxes	44.5	41.4
Income tax provision	13.4	7
Net income	$ 31.1	$ 34.4
Net income per share:
Basic (in dollars per share)	$ 0.09	$ 0.10
Diluted, (in dollars per share)	$ 0.09	$ 0.10
Shares used in computing net income per share:
Basic (in shares)	348.1	355.3
Diluted (in shares)	352.7	360.6
Product
Total net revenues	$ 618.7	$ 710.8
Cost of revenues:
Total cost of revenues	270	306.4
Service
Total net revenues	383	371.8
Cost of revenues:
Total cost of revenues	$ 149.4	$ 157.8

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 31.1	$ 34.4
Available-for-sale debt securities:
Change in net unrealized gains and losses, net of tax (provision) benefit of ($0.6) and $1.4, respectively	1.8	(2)
Net realized losses reclassified into net income, net of tax provisions of zero and zero, respectively	0	0.9
Net change on available-for-sale debt securities, net of tax	1.8	(1.1)
Cash flow hedges:
Change in net unrealized gains and losses, net of tax provision of $1.3 and $0.3, respectively	2.1	13.1
Net realized (gains) losses reclassified into net income, net of tax provisions of $0.2 and $0.6, respectively	1.2	(5.1)
Net change on cash flow hedges, net of tax	3.3	8
Change in foreign currency translation adjustments	2.2	5.3
Other comprehensive income, net of tax	7.3	12.2
Comprehensive income	$ 38.4	$ 46.6

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Unrealized gain (loss) on available-for-sale securities, tax (provision) benefit	$ (0.6)	$ 1.4
Reclassification adjustment for realized net loss (gain) on available-for-sale securities included in net income, tax provisions	0	0
Unrealized (loss) gain on cash flow hedges, tax (provision) benefit	(1.3)	(0.3)
Reclassification adjustment for realized net loss (gain) on cash flow hedges included in net income, tax provisions (benefit)	$ 0.2	$ 0.6

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 2,155.6	$ 2,489
Short-term investments	1,227.4	1,070.1
Accounts receivable, net of allowances	645.4	754.6
Prepaid expenses and other current assets	281.2	268.1
Total current assets	4,309.6	4,581.8
Property and equipment, net	892.4	951.7
Operating lease assets	184.2
Long-term investments	119.7	199
Purchased intangible assets, net	113.5	118.5
Goodwill	3,109.3	3,108.8
Other long-term assets	409.2	403.5
Total assets	9,137.9	9,363.3
Current liabilities:
Accounts payable	219.1	208.8
Accrued compensation	166.8	221
Deferred revenue	860.1	829.3
Short-term portion of long-term debt	0	349.9
Other accrued liabilities	243.1	233.5
Total current liabilities	1,489.1	1,842.5
Long-term debt	1,789.6	1,789.1
Long-term deferred revenue	370.8	384.3
Long-term income taxes payable	407.3	404.4
Long-term operating lease liabilities	176.7
Other long-term liabilities	53.2	119.8
Total liabilities	4,286.7	4,540.1
Commitments and contingencies (Note 13)
Stockholders' equity:
Convertible preferred stock, $0.00001 par value; 10.0 shares authorized; none issued and outstanding	0	0
Common stock, $0.00001 par value; 1,000.0 shares authorized; 352.0 shares and 346.4 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	0	0
Additional paid-in capital	7,668.6	7,672.8
Accumulated other comprehensive loss	(10.9)	(18.2)
Accumulated deficit	(2,806.5)	(2,831.4)
Total stockholders' equity	4,851.2	4,823.2
Total liabilities and stockholders' equity	$ 9,137.9	$ 9,363.3

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parentheticals) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Convertible preferred stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Convertible preferred stock - shares authorized (shares)	10,000,000	10,000,000
Convertible preferred stock - issued (shares)	0	0
Convertible preferred stock - outstanding (shares)	0	0
Common stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock - shares authorized (shares)	1,000,000,000	1,000,000,000
Common stock - issued (shares)	352,000,000	346,400,000
Common stock - outstanding (shares)	352,000,000	346,400,000

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 31.1	$ 34.4
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	33.9	70.4
Depreciation, amortization, and accretion	48.7	55.7
Other	(2.2)	1.7
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable, net	108.6	170.8
Prepaid expenses and other assets	0.5	(11.7)
Accounts payable	10.1	(31.2)
Accrued compensation	(54.9)	(14.1)
Income taxes payable	(5.7)	(7.6)
Other accrued liabilities	(27.9)	(51.1)
Deferred revenue	17.2	53.8
Net cash provided by operating activities	159.4	271.1
Cash flows from investing activities:
Purchases of property and equipment	(27.9)	(42.2)
Purchases of available-for-sale debt securities	(884.4)	(8.1)
Proceeds from sales of available-for-sale debt securities	232.8	968
Proceeds from maturities and redemptions of available-for-sale debt securities	578.3	215.4
Purchases of equity securities	(5.1)	(2)
Proceeds from sales of equity securities	2.2	3.3
Subsequent payments related to acquisitions in prior years	0	(22.2)
Net cash (used in) provided by investing activities	(104.1)	1,112.2
Cash flows from financing activities:
Repurchase and retirement of common stock	(2.9)	(754.2)
Proceeds from issuance of common stock	29.5	29.3
Payment of dividends	(66.2)	(62.1)
Change in customer financing arrangement	0	(16.6)
Payment of debt	(350)	0
Net cash used in financing activities	(389.6)	(803.6)
Effect of foreign currency exchange rates on cash, cash equivalents, and restricted cash	1.6	6.2
Net increase in cash, cash equivalents, and restricted cash	(332.7)	585.9
Cash, cash equivalents, and restricted cash at beginning of period	2,505.8	2,059.1
Cash, cash equivalents, and restricted cash at end of period	$ 2,173.1	$ 2,645

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Common Stock and Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Balance (in shares) at Dec. 31, 2017		365.5
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	34.4				34.4
Other comprehensive income (loss), net	12.2			12.2
Issuance of common stock (in shares)		7
Issuance of common stock	29.3		29.3
Repurchase and retirement of common stock (in shares)		(23.5)
Repurchase and retirement of common stock	(604.2)		(314.4)		(289.8)
Purchase of equity forward contract	(150)
Share-based compensation expense	70.6		70.6
Payments of cash dividends	(62.1)		(62.1)
Balance (in shares) at Mar. 31, 2018		349
Balance at Mar. 31, 2018	4,324.7		7,615.5	12.5	(3,303.3)
Balance (in shares) at Dec. 31, 2018		346.4
Balance at Dec. 31, 2018	4,823.2		7,672.8	(18.2)	(2,831.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31.1				31.1
Other comprehensive income (loss), net	7.3			7.3
Issuance of common stock (in shares)		5.7
Issuance of common stock	29.5		29.5
Repurchase and retirement of common stock (in shares)		(0.1)
Repurchase and retirement of common stock	(2.9)		(1.4)		(1.5)
Share-based compensation expense	33.9		33.9
Payments of cash dividends	(66.2)		(66.2)
Balance (in shares) at Mar. 31, 2019		352
Balance at Mar. 31, 2019	$ 4,851.2		$ 7,668.6	$ (10.9)	$ (2,806.5)

Condensed Consolidated Statem_6

Condensed Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - $ / shares	Mar. 22, 2019	Mar. 31, 2019	Mar. 31, 2018
Statement of Stockholders' Equity [Abstract]
Cash dividends (in dollars per share)	$ 0.19	$ 0.19	$ 0.18

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation Basis of Presentation The unaudited Condensed Consolidated Financial Statements of Juniper Networks, Inc. (the “Company” or “Juniper”) have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet as of December 31, 2018 has been derived from the audited Consolidated Financial Statements at that date. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 , or any future period. The information included in this Quarterly Report on Form 10-Q (“Report”) should be read in conjunction with “Management's Discussion and Analysis of Financial Condition and Results of Operations,” “Risk Factors,” “Quantitative and Qualitative Disclosures About Market Risk,” and the Consolidated Financial Statements and footnotes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 (the "Form 10-K"). The preparation of the financial statements and related disclosures in accordance with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates under different assumptions or conditions.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Except for the change in certain policies upon adoption of the accounting standards described below, there have been no material changes to the Company's significant accounting policies, compared to the accounting policies described in Note 2, Significant Accounting Policies , in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K. 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 has adopted the standard prospectively and had no material impact to all applicable implementation costs incurred after the adoption date. 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 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 Condensed Consolidated Financial Statements. See Note 5, 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 Condensed 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 Condensed 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 Condensed Consolidated Statements of Operations and Condensed Consolidated Statements of Cash Flows or debt-covenant compliance under its current agreements. See Note 13, Commitment and Contingencies, for additional disclosures required upon adopting the standard. Leases The Company determines if an arrangement is a lease at inception. The Company evaluates classification of leases at commencement and, as necessary, at modification. As of March 31, 2019, the Company did not have any finance leases. Operating leases are included in operating lease ROU assets, other accrued liabilities, and operating lease liabilities on the Company's Condensed 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 at commencement date based on the present value of lease payments over the lease term. 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. Recent Accounting Standards Not Yet Adopted 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, with early adoption permitted. The Company is currently evaluating the impact of adoption on the 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 now 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, with early adoption permitted for any impairment tests performed after January 1, 2017. The Company does not expect the adoption to have a material impact on the Consolidated Financial Statements. Credit Losses on Financial Instruments: In June 2016, the FASB issued ASU No. 2016-13 (Topic 326) Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments , which provides more decision-useful information about the expected credit losses on financial instruments and changes the loss impairment methodology. Further amendment issued by the FASB in November 2018 clarifies that receivables arising from operating leases are not within the scope of Topic 326 and should be accounted for in accordance with Topic 842. This pronouncement and its amendment are effective for reporting periods beginning after December 15, 2019, and interim periods within those fiscal years, using a modified retrospective adoption method. Early adoption is permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements.

Cash Equivalents and Investment

Cash Equivalents and Investments	3 Months Ended
	Mar. 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 March 31, 2019 and December 31, 2018 (in millions): As of March 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 $ 30.4 $ — $ (0.1 ) $ 30.3 $ 46.8 $ — $ (0.3 ) $ 46.5 Certificates of deposit 95.4 — — 95.4 152.9 — — 152.9 Commercial paper 377.5 — — 377.5 393.6 — — 393.6 Corporate debt securities 363.3 — (1.3 ) 362.0 416.1 — (3.1 ) 413.0 Foreign government debt securities 38.4 — (0.1 ) 38.3 20.0 — (0.1 ) 19.9 Time deposits 84.2 — — 84.2 278.6 — — 278.6 U.S. government agency securities 25.7 — (0.1 ) 25.6 87.2 — (0.2 ) 87.0 U.S. government securities 746.6 0.1 (0.3 ) 746.4 811.8 — (0.5 ) 811.3 Total fixed income securities 1,761.5 0.1 (1.9 ) 1,759.7 2,207.0 — (4.2 ) 2,202.8 Privately-held debt and redeemable preferred stock securities 14.6 37.4 — 52.0 16.6 37.4 — 54.0 Total available-for-sale debt securities $ 1,776.1 $ 37.5 $ (1.9 ) $ 1,811.7 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8 Reported as: Cash equivalents $ 414.4 $ — $ — $ 414.4 $ 936.5 $ — $ — $ 936.5 Short-term investments 1,226.7 0.1 (1.2 ) 1,225.6 1,069.2 — (1.9 ) 1,067.3 Long-term investments 120.4 — (0.7 ) 119.7 201.3 — (2.3 ) 199.0 Other long-term assets 14.6 37.4 — 52.0 16.6 37.4 — 54.0 Total $ 1,776.1 $ 37.5 $ (1.9 ) $ 1,811.7 $ 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 March 31, 2019 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,641.1 $ 1,640.0 Due between one and five years 120.4 119.7 Total $ 1,761.5 $ 1,759.7 The following tables present the Company's total fixed income securities that were in an unrealized loss position as of March 31, 2019 and December 31, 2018 (in millions): As of March 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 $ 0.2 $ — $ 27.7 $ (0.1 ) $ 27.9 $ (0.1 ) Corporate debt securities 47.3 — 278.1 (1.3 ) 325.4 (1.3 ) Foreign government debt securities 5.5 — 17.3 (0.1 ) 22.8 (0.1 ) U.S. government agency securities — — 23.6 (0.1 ) 23.6 (0.1 ) U.S. government securities 312.0 — 46.4 (0.3 ) 358.4 (0.3 ) Total fixed income securities $ 365.0 $ — $ 393.1 $ (1.9 ) $ 758.1 $ (1.9 ) 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 March 31, 2019 , the Company had 382 investments in unrealized loss positions. The gross unrealized losses related to these investments were primarily due to changes in market interest rates. The Company anticipates that it will recover the entire amortized cost basis of such available-for-sale debt securities and has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the three months ended March 31, 2019 and March 31, 2018 . During the three months ended March 31, 2019 and March 31, 2018 , 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 March 31, 2019 and December 31, 2018 (in millions): As of March 31, December 31, Equity investments with readily determinable fair value Money market funds (1) $ 836.7 $ 996.9 Mutual funds (2) 26.2 24.3 Publicly-traded equity securities 1.8 2.8 Equity investments without readily determinable fair value 42.1 36.4 Total equity securities $ 906.8 $ 1,060.4 Reported as: Cash equivalents $ 825.1 $ 985.3 Short-term investments 1.8 2.8 Prepaid expenses and other current assets 11.2 10.9 Other long-term assets 68.7 61.4 Total $ 906.8 $ 1,060.4 ________________________________ (1) Balance includes $11.6 million and $11.6 million in restricted investments measured at fair value, related to the Company's acquisition-related escrow accounts as of March 31, 2019 and December 31, 2018 , respectively. (2) Balance relates to restricted investments measured at fair value related to the Company's Deferred Compensation Plan. For the three months ended March 31, 2019 and March 31, 2018 , there were no material unrealized gains or losses recognized for equity investments. Restricted Cash and Investments As of March 31, 2019 , the carrying value of restricted cash and investments was $55.3 million , of which $28.8 million was included in prepaid expenses and other current assets and $26.5 million was included in other long-term assets on the Condensed Consolidated Balance Sheet. The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Condensed Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 (in millions): As of March 31, December 31, Cash and cash equivalents $ 2,155.6 $ 2,489.0 Restricted cash included in Prepaid expenses and other current assets 17.5 16.8 Total cash, cash equivalents, and restricted cash $ 2,173.1 $ 2,505.8

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 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 Condensed 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 $ — $ 30.3 $ — $ 30.3 $ — $ 46.5 $ — $ 46.5 Certificates of deposit — 95.4 — 95.4 — 152.9 — 152.9 Commercial paper — 377.5 — 377.5 — 393.6 — 393.6 Corporate debt securities — 362.0 — 362.0 — 413.0 — 413.0 Foreign government debt securities — 38.3 — 38.3 — 19.9 — 19.9 Time deposits — 84.2 — 84.2 — 278.6 — 278.6 U.S. government agency securities — 25.6 — 25.6 — 87.0 — 87.0 U.S. government securities 412.9 333.5 — 746.4 352.8 458.5 — 811.3 Privately-held debt and redeemable preferred stock securities — — 52.0 52.0 — — 54.0 54.0 Total available-for-sale debt securities 412.9 1,346.8 52.0 1,811.7 352.8 1,850.0 54.0 2,256.8 Equity securities: Money market funds 836.7 — — 836.7 996.9 — — 996.9 Mutual funds 26.2 — — 26.2 24.3 — — 24.3 Publicly-traded equity securities 1.8 — — 1.8 2.8 — — 2.8 Total equity securities 864.7 — — 864.7 1,024.0 — — 1,024.0 Derivative assets: Foreign exchange contracts — 8.4 — 8.4 — 5.3 — 5.3 Total assets measured at fair value $ 1,277.6 $ 1,355.2 $ 52.0 $ 2,684.8 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Liabilities: Derivative liabilities: Foreign exchange contracts $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total liabilities measured at fair value $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total assets, reported as: Cash equivalents $ 825.1 $ 414.4 $ — $ 1,239.5 $ 1,025.2 $ 896.6 $ — $ 1,921.8 Short-term investments 406.2 821.2 — 1,227.4 297.5 772.6 — 1,070.1 Long-term investments 8.5 111.2 — 119.7 18.2 180.8 — 199.0 Prepaid expenses and other current assets 11.3 8.4 — 19.7 10.8 5.3 — 16.1 Other long-term assets 26.5 — 52.0 78.5 25.1 — 54.0 79.1 Total assets measured at fair value $ 1,277.6 $ 1,355.2 $ 52.0 $ 2,684.8 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Total liabilities, reported as: Other accrued liabilities $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total liabilities measured at fair value $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (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 three months ended March 31, 2019 , the Company had no transfers between levels of the fair value hierarchy of its assets or liabilities measured at fair value. All of 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 three months ended March 31, 2019 , there were no significant activities related to privately-held debt and redeemable preferred stock securities. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis 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 three months ended March 31, 2019 . Equity investments without readily determinable fair value are measured at fair value, when they are deemed to be impaired or when there is an adjustment from observable price changes. For the three months ended March 31, 2019 , there were no material impairment charges or adjustments resulting from observable price changes for equity investments without readily determinable fair value. As of March 31, 2019 and December 31, 2018 , the Company had no liabilities required to be measured at fair value on a nonrecurring basis. Assets and Liabilities Not Measured at Fair Value The carrying amounts of the Company's accounts receivable, accounts payable, and other accrued liabilities approximate fair value due to their short maturities. As of March 31, 2019 and December 31, 2018 , the estimated fair value of the Company's total outstanding debt in the Condensed Consolidated Balance Sheets was $1,856.2 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, along with the accumulated interest paid in kind, of $69.0 million approximates its fair value as of March 31, 2019 and December 31, 2018 . 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 $47.6 million , reported within other long-term assets, in the Condensed Consolidated Balance Sheets approximates its fair value as of March 31, 2019 . See Note 6, Other Financial Information, for further information on the contract manufacturer deposit.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The Company uses derivatives to partially offset its market exposure to fluctuations in certain foreign currencies and does not enter into derivatives for speculative or trading purposes. The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions): As of March 31, December 31, Cash flow hedges $ 377.0 $ 497.7 Non-designated derivatives 175.6 158.7 Total $ 552.6 $ 656.4 Cash Flow Hedges 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. Execution of cash flow hedge derivatives typically occurs every month with maturities of eighteen months or less. As of March 31, 2019 , an estimated $2.8 million of unrealized net gain within accumulated other comprehensive loss is expected to be reclassified into earnings within the next 12 months. The Company recognized an unrealized gain of $3.4 million and $13.4 million in accumulated other comprehensive income for the effective portion of its derivative instruments for the three months ended March 31, 2019 and March 31, 2018 , respectively. The Company reclassified a loss of $1.0 million and a gain of $5.6 million out of accumulated other comprehensive income to cost of revenues and operating expenses in the Condensed Consolidated Statements of Operations during the three months ended March 31, 2019 and March 31, 2018 , respectively. See Note 4, Fair Value Measurements , for the fair values of the Company's derivative instruments in the Condensed Consolidated Balance Sheets. 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 three 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 Condensed Consolidated Statements of Operations were not material during the three months ended March 31, 2019 and March 31, 2018 .

Other Financial Information

Other Financial Information	3 Months Ended
	Mar. 31, 2019
Other Financial Information [Abstract]
Other Financial Information	Other Financial Information Inventory Total inventory consisted of the following (in millions): As of March 31, December 31, Production and service materials $ 72.6 $ 60.6 Finished goods 21.3 21.4 Inventory $ 93.9 $ 82.0 Reported as: Prepaid expenses and other current assets $ 92.4 $ 80.6 Other long-term assets 1.5 1.4 Total $ 93.9 $ 82.0 Deposit The Company has a non-interest bearing deposit balance of $47.6 million , net of an unamortized discount balance of $2.3 million , to a contract manufacturer per the terms of the agreement. The discount is calculated based on an imputed interest rate of 4.8% at March 31, 2019 . The imputed interest will be amortized over the term of the deposit to interest income along with a corresponding charge to cost of revenues. The deposit is due on demand in the second quarter of 2020 and has been classified as other long-term assets on the Condensed Consolidated Balance Sheets. Warranties Changes during the three months ended March 31, 2019 in the Company’s warranty reserve as reported within other accrued liabilities in the Condensed Consolidated Balance Sheets were as follows (in millions): Balance as of December 31, 2018 $ 28.0 Provisions made during the period 8.6 Actual costs incurred during the period (7.7 ) Balance as of March 31, 2019 $ 28.9 Deferred Revenue Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions): As of March 31, December 31, Deferred product revenue: Undelivered product commitments and other product deferrals $ 152.3 $ 163.3 Deferred gross product revenue 152.3 163.3 Deferred cost of product revenue (12.7 ) (18.9 ) Deferred product revenue, net 139.6 144.4 Deferred service revenue 1,091.3 1,069.2 Total $ 1,230.9 $ 1,213.6 Reported as: Current $ 860.1 $ 829.3 Long-term 370.8 384.3 Total $ 1,230.9 $ 1,213.6 Revenue See Note 10, Segments, for disaggregated revenue by product and service, customer vertical, and geographic region. The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of March 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 $ 152.3 $ 122.8 $ 26.0 $ 3.5 Service 1,091.3 750.0 285.8 55.5 Total $ 1,243.6 $ 872.8 $ 311.8 $ 59.0 Deferred Commissions Deferred commissions were $26.1 million as of March 31, 2019 . For the three months ended March 31, 2019 , amortization expense for the deferred commissions was $34.9 million . There were no impairment charges recognized during the three months ended March 31, 2019 . Other Income (Expense), Net Other income (expense), net, consisted of the following (in millions): Three Months Ended March 31, 2019 2018 Interest income $ 23.5 $ 14.9 Interest expense (24.2 ) (26.0 ) Gain (loss) on investments, net 1.6 (0.5 ) Other 0.9 (2.5 ) Other income (expense), net $ 1.8 $ (14.1 )

Restructuring Charges

Restructuring Charges	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges During the first quarter of 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. The 2019 Restructuring Plan consists of workforce reductions and facility closures. In connection with the 2019 Restructuring Plan, the Company recorded $15.1 million of severance costs and $0.2 million of facility consolidations, respectively, to restructuring charges in the Condensed Consolidated Statements of Operations during the three months ended March 31, 2019 Restructuring liabilities are reported within other accrued liabilities in the Condensed Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liabilities for the Company's 2019 and prior year plans (in millions): December 31, Charges Cash Payments Other March 31, Severance $ 1.1 $ 15.1 $ (10.1 ) $ (0.1 ) $ 6.0 Facility consolidations — 0.2 (0.1 ) (0.1 ) — Total $ 1.1 $ 15.3 $ (10.2 ) $ (0.2 ) $ 6.0 The Company expects to pay the remaining restructuring liabilities by the end of the third quarter of 2019.

Equity

Equity	3 Months Ended
	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Equity	Equity The following table summarizes dividends paid, stock repurchases and retirements under the Company's stock repurchase program (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 (1)(2) Dividends Per share $ 0.19 $ 0.18 Amount $ 66.2 $ 62.1 Stock repurchases Shares — 23.3 Average price per share $ — $ 25.80 Amount $ — $ 750.0 ________________________________ (1) Shares repurchased under the 2018 Stock Repurchase Program. (2) $750.0 million represents the full amount of the accelerated share repurchase program (the "ASR") for which 23.3 million shares were received initially during the first quarter of 2018, and an additional 6.0 million shares were received at final settlement during the third quarter of 2018. Cash Dividends on Shares of Common Stock During the three months ended March 31, 2019 , the Company declared a quarterly cash dividend of $0.19 per share of common stock on January 29, 2019, which was paid on March 22, 2019 to stockholders of record on March 1, 2019. Any future dividends, and the establishment of record and payment dates, are subject to approval by the Board of Directors (the “Board”) of Juniper or an authorized committee thereof. See Note 14, Subsequent Event, for discussion of the Company's dividend declaration subsequent to March 31, 2019 . Stock Repurchase Activities In January 2018, the Board approved a $2.0 billion share repurchase program ("2018 Stock Repurchase Program"). As part of the 2018 Stock Repurchase Program, in February 2018, the Company entered into an ASR to repurchase $750.0 million of its common stock. The Company made an up-front payment of $750.0 million pursuant to the ASR to repurchase its common stock. The aggregate number of shares ultimately repurchased of 29.3 million shares of common stock was determined based on a volume weighted average repurchase price, less an agreed upon discount, of $25.62 per share. As of March 31, 2019 , there were $1.3 billion of authorized funds remaining under the 2018 Stock Repurchase Program. Future share repurchases under the 2018 Stock Repurchase Program will be subject to a review of the circumstances at that time and will be made from time to time in private transactions or open market purchases as permitted by securities laws and other legal requirements. The Company's 2018 Stock Repurchase Program may be discontinued at any time. In addition to repurchases under the 2018 Stock Repurchase Program, the Company also repurchases common stock from certain employees in connection with the net issuance of shares to satisfy applicable tax withholding requirements upon the vesting of certain stock awards issued to such employees. Repurchases associated with tax withholdings were not material during the three months ended March 31, 2019 and March 31, 2018 . Accumulated Other Comprehensive Loss, Net of Tax The components of accumulated other comprehensive loss, net of related taxes, for the three months ended March 31, 2019 were as follows (in millions): Unrealized Gains/Losses on Available-for- Sale Debt Securities Unrealized Gains/Losses on Cash Flow Hedges Foreign Currency Translation Adjustments Total Balance as of December 31, 2018 $ 25.5 $ (0.9 ) $ (42.8 ) $ (18.2 ) Other comprehensive income before reclassifications 1.8 2.1 2.2 6.1 Amount reclassified from accumulated other comprehensive loss — 1.2 — 1.2 Other comprehensive income, net 1.8 3.3 2.2 7.3 Balance as of March 31, 2019 $ 27.3 $ 2.4 $ (40.6 ) $ (10.9 )

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefit Plans	Employee Benefit Plans Equity Incentive Plans The Company has stock-based compensation plans pursuant to which it has granted stock options, restricted stock units (“RSUs”), and performance share awards (“PSAs”). The Company also maintains its 2008 Employee Stock Purchase Plan (the “ESPP”) for all eligible employees. As of March 31, 2019 , 11.4 million and 7.4 million shares were available for future issuance under the Company's 2015 Equity Incentive Plan (the "2015 Plan") and the ESPP, respectively. In connection with past acquisitions, the Company also assumed or substituted stock options, RSUs, RSAs, and PSAs. Restricted Stock Unit and Performance Share Award Activities The Company’s RSU and PSA activity and related information as of and for the three months ended March 31, 2019 were as follows (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 as of December 31, 2018 17.4 $ 25.32 RSUs granted (1)(3) 5.5 25.53 PSAs granted (2)(3) 0.7 25.06 RSUs vested (3.9 ) 26.00 RSAs vested (0.1 ) 23.13 PSAs vested (0.5 ) 26.76 RSUs canceled (0.8 ) 26.32 PSAs canceled (0.6 ) 23.25 Balance as of March 31, 2019 17.7 $ 25.21 1.5 $ 467.8 ________________________________ (1) Includes service-based and market-based RSUs. The number of shares subject to market-based condition 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 market-based condition that would be issued if market criteria determined by the Compensation Committee of the Board are achieved at target is 0.2 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 0.4 million shares. (2) 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 these PSAs that would be issued if performance goals determined by the Compensation Committee of the Board are achieved at target is 0.4 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 0.7 million shares. (3) The grant date fair value of RSUs and PSAs were 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 the three months ended March 31, 2019 , the Company declared a quarterly cash dividend of $0.19 per share of common stock on January 29, 2019. (4) 0.3 million shares of PSAs were modified during the three months ended March 31, 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 $7.7 million to be recognized over the remaining terms of the modified awards. Employee Stock Purchase Plan The following table summarizes employee stock purchases through the ESPP (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 Shares purchased 1.2 1.3 Average exercise price per share $ 22.04 $ 22.23 On November 6, 2017, the Company’s Compensation Committee amended and restated the ESPP to provide that the offering period that began on February 1, 2018 would be for 24 months 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. Share-Based Compensation Expense Share-based compensation expense associated with stock options, RSUs, restricted stock awards ("RSAs"), PSAs, and the ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions): Three Months Ended March 31, 2019 2018 Cost of revenues - Product $ 1.9 $ 1.9 Cost of revenues - Service 4.5 4.8 Research and development 12.2 44.1 Sales and marketing 9.4 13.5 General and administrative 5.9 6.1 Total $ 33.9 $ 70.4 The following table summarizes share-based compensation expense by award type (in millions): Three Months Ended March 31, 2019 2018 Stock options $ 0.1 $ 0.1 RSUs, RSAs, and PSAs 29.1 65.6 ESPP 4.7 4.7 Total $ 33.9 $ 70.4 As of March 31, 2019 , the total unrecognized compensation cost related to unvested share-based awards was $369.5 million to be recognized over a weighted-average period of 1.9 years.

Segments

Segments	3 Months Ended
	Mar. 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): Three Months Ended March 31, 2019 2018 Routing $ 374.7 $ 408.1 Switching 176.4 230.0 Security 67.6 72.7 Total product 618.7 710.8 Total service 383.0 371.8 Total $ 1,001.7 $ 1,082.6 The following table presents net revenues by customer vertical (*) (in millions): Three Months Ended March 31, 2019 2018 Cloud $ 223.1 $ 270.9 Service Provider 435.6 480.1 Enterprise 343.0 331.6 Total $ 1,001.7 $ 1,082.6 ________________________________ (*) Certain insignificant prior-period amounts have been reclassified to conform to the current-period presentation. The Company attributes revenues to geographic region based on the customer’s shipping address. The following table presents net revenues by geographic region (in millions): Three Months Ended March 31, 2019 2018 Americas: United States $ 476.6 $ 532.3 Other 67.0 55.3 Total Americas 543.6 587.6 Europe, Middle East, and Africa 286.2 308.0 Asia Pacific 171.9 187.0 Total $ 1,001.7 $ 1,082.6

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The following table provides details of income taxes (in millions, except percentages): Three Months Ended March 31, 2019 2018 Income before income taxes $ 44.5 $ 41.4 Income tax provision $ 13.4 $ 7.0 Effective tax rate 30.1 % 16.9 % The Company's effective tax rate during the three months ended March 31, 2019 differs from the federal statutory rate of 21% , primarily due to the benefit of the federal research and development ("R&D") credit and foreign earnings taxed at lower rates partially offset in the U.S. by the Base Erosion and Anti-Abuse Tax and state income taxes. The increase in the rate reflects the inability to fully benefit the discrete charges in the period and the net impact of unrecognized tax benefits. The effective tax rate during the three months ended March 31, 2018 differs from the federal statutory rate of 21% primarily due to the net impact of previously unrecognized tax benefits. As of March 31, 2019 , the total amount of gross unrecognized tax benefits was $181.6 million , of which $178.2 million , if recognized, would affect the effective tax rate. The Company engages in continuous discussions and negotiations with tax authorities regarding tax matters in various jurisdictions. It is reasonably possible that the balance of unrecognized tax benefits could decrease up to $30.4 million within the next twelve months due to lapses of applicable statutes of limitations and the completion of tax review cycles in various tax jurisdictions.

Net Income Per Share

Net Income Per Share	3 Months Ended
	Mar. 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): Three Months Ended March 31, 2019 2018 Numerator: Net income $ 31.1 $ 34.4 Denominator: Weighted-average shares used to compute basic net income per share 348.1 355.3 Dilutive effect of employee stock awards 4.6 5.3 Weighted-average shares used to compute diluted net income per share 352.7 360.6 Net income per share Basic $ 0.09 $ 0.10 Diluted $ 0.09 $ 0.10 Anti-dilutive shares 5.0 10.4

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Except for the items below, there have been no material changes to the Company's commitments compared to the commitments described in Note 16, Commitments and Contingencies , in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K. Leases The Company leases its facilities and certain equipment under non-cancelable operating leases that have remaining lease terms of 1 to 7 years and 1 to 3 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): Three Months Ended March 31, 2019 Operating lease cost $ 11.9 Variable lease cost 3.1 Total lease cost $ 15.0 Operating cash outflows from operating leases $ 11.6 ROU assets obtained in exchange for new operating lease liabilities $ 0.6 Weighted average remaining lease term (years) 6.0 Weighted average discount rate 4.4 % As of March 31, 2019 , future minimum operating lease payments for each of the next five years and thereafter is as follows (in millions): Years Ending December 31, Amount 2019 $ 32.9 2020 47.3 2021 40.4 2022 32.7 2023 29.8 Thereafter 60.3 Total lease payments 243.4 Less: interest (30.0 ) Total $ 213.4 Balance Sheet Information Other accrued liabilities 36.7 Long-term operating lease liabilities 176.7 Total $ 213.4 Purchase Commitments with Contract Manufacturers and Suppliers In order to reduce manufacturing lead times and in the interest of having access to adequate component supply, the Company enters into agreements with contract manufacturers and certain suppliers to procure inventory based on the Company's requirements. A significant portion of the Company's purchase commitments arising from these agreements consists of firm and non-cancelable commitments. These purchase commitments totaled $632.4 million as of March 31, 2019 . 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 March 31, 2019 , the Company had accrued $32.8 million based on its estimate of such charges. Indebtedness In February 2019, the Company paid the aggregate principal amount of $350.0 million on its 3.125% senior notes upon maturity. Legal Proceedings Investigations The Company previously disclosed that it has been the subject of investigations by the U.S. Securities and Exchange Commission ("SEC") and the U.S. Department of Justice ("DOJ") into possible violations by the Company of the U.S. Foreign Corrupt Practices Act. In cooperation with these investigations, the Company and the Audit Committee of the Board of Directors, with the assistance of outside counsel and other independent advisors, conducted a thorough internal investigation. As a result of its internal investigation, the Company made significant improvements in its internal controls and carried out a number of disciplinary actions. In the fourth quarter of 2017, the DOJ notified the Company that the DOJ has closed its investigation related to these matters without taking any action against the Company. The Company is continuing to fully cooperate with the SEC’s ongoing investigation, and based on the Company’s recent communications with the Staff of the SEC, the Company believes that it is likely that the Staff of the SEC will seek to bring an enforcement action against the Company. The Company believes it is probable that it could incur a loss and has established an estimated legal reserve of $12.0 million related to the ongoing SEC investigation; however, as discussions are continuing, there can be no assurance as to the timing or the terms of any final resolution of this matter. Other Litigations and Investigations In addition to the investigations discussed above, the Company is involved in other 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.

Subsequent Event

Subsequent Event	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event Mist Acquisition On April 1, 2019 , the Company completed the acquisition of Mist Systems, Inc. (“Mist”), a software company that provides cloud-managed wireless networks powered by artificial intelligence ("AI") for approximately $365.0 million in cash consideration, subject to adjustments for cash on hand, up to a certain limit, indebtedness, and certain other closing adjustments. A portion of the consideration includes certain share-based awards attributable to services prior to the acquisition. Credit Facility In April 2019, the Company entered into a new 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. The Revolving Credit Facility will terminate in April 2024, subject to two one -year maturity extension options, on the terms and conditions set forth in the Revolving Credit Facility. Dividend Declaration On April 25, 2019 , the Company announced that the Board declared a cash dividend of $0.19 per share of common stock to be paid on June 24, 2019 to stockholders of record as of the close of business on June 3, 2019 . Stock Repurchase Activities The Board also authorized the Company to enter into an ASR for an amount up to $300.0 million under the 2018 Stock Repurchase Program. On April 29, 2019, the Company entered into an ASR with a financial institution, to repurchase an aggregate of approximately $300.0 million of the Company’s outstanding common stock. The Company made an up-front payment of $300.0 million pursuant to the ASR and received and retired an initial 8.6 million shares of the Company’s common stock for an aggregate price of $240.0 million based on the market value of the Company’s common stock on the date of the transaction. The Company has an aggregate of $1.0 billion of authorized funds remaining under the 2018 Stock Repurchase Program, as of the filing of this Quarterly Report on Form 10-Q. 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. Restructuring In April 2019, the Company amended the 2019 Restructuring Plan to implement certain additional organizational changes resulting in a realignment of the Company's workforce. As a result, the Company expects to record severance charges of approximately $6.0 million to $7.5 million related to headcount reductions in the second quarter of 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited Condensed Consolidated Financial Statements of Juniper Networks, Inc. (the “Company” or “Juniper”) have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet as of December 31, 2018 has been derived from the audited Consolidated Financial Statements at that date. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three months ended March 31, 2019 are not necessarily indicative of the results that may be expected for the year ending December 31, 2019 , or any future period. The information included in this Quarterly Report on Form 10-Q (“Report”) should be read in conjunction with “Management's Discussion and Analysis of Financial Condition and Results of Operations,” “Risk Factors,” “Quantitative and Qualitative Disclosures About Market Risk,” and the Consolidated Financial Statements and footnotes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2018 (the "Form 10-K"). The preparation of the financial statements and related disclosures in accordance with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates under different assumptions or conditions.
Recently Adopted Accounting Standards 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 has adopted the standard prospectively and had no material impact to all applicable implementation costs incurred after the adoption date. 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 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 Condensed Consolidated Financial Statements. See Note 5, 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 Condensed 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 Condensed 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 Condensed Consolidated Statements of Operations and Condensed Consolidated Statements of Cash Flows or debt-covenant compliance under its current agreements. See Note 13, Commitment and Contingencies, for additional disclosures required upon adopting the standard. Leases The Company determines if an arrangement is a lease at inception. The Company evaluates classification of leases at commencement and, as necessary, at modification. As of March 31, 2019, the Company did not have any finance leases. Operating leases are included in operating lease ROU assets, other accrued liabilities, and operating lease liabilities on the Company's Condensed 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 at commencement date based on the present value of lease payments over the lease term. 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. Recent Accounting Standards Not Yet Adopted 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, with early adoption permitted. The Company is currently evaluating the impact of adoption on the 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 now 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, with early adoption permitted for any impairment tests performed after January 1, 2017. The Company does not expect the adoption to have a material impact on the Consolidated Financial Statements. Credit Losses on Financial Instruments: In June 2016, the FASB issued ASU No. 2016-13 (Topic 326) Financial Instruments—Credit Losses: Measurement of Credit Losses on Financial Instruments , which provides more decision-useful information about the expected credit losses on financial instruments and changes the loss impairment methodology. Further amendment issued by the FASB in November 2018 clarifies that receivables arising from operating leases are not within the scope of Topic 326 and should be accounted for in accordance with Topic 842. This pronouncement and its amendment are effective for reporting periods beginning after December 15, 2019, and interim periods within those fiscal years, using a modified retrospective adoption method. Early adoption is permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of new accounting pronouncements and changes in accounting principles	The cumulative effect of the adjustments made to the Company's Condensed 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 )

Cash Equivalents and Investme_2

Cash Equivalents and Investments (Tables)	3 Months Ended
	Mar. 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 March 31, 2019 and December 31, 2018 (in millions): As of March 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 $ 30.4 $ — $ (0.1 ) $ 30.3 $ 46.8 $ — $ (0.3 ) $ 46.5 Certificates of deposit 95.4 — — 95.4 152.9 — — 152.9 Commercial paper 377.5 — — 377.5 393.6 — — 393.6 Corporate debt securities 363.3 — (1.3 ) 362.0 416.1 — (3.1 ) 413.0 Foreign government debt securities 38.4 — (0.1 ) 38.3 20.0 — (0.1 ) 19.9 Time deposits 84.2 — — 84.2 278.6 — — 278.6 U.S. government agency securities 25.7 — (0.1 ) 25.6 87.2 — (0.2 ) 87.0 U.S. government securities 746.6 0.1 (0.3 ) 746.4 811.8 — (0.5 ) 811.3 Total fixed income securities 1,761.5 0.1 (1.9 ) 1,759.7 2,207.0 — (4.2 ) 2,202.8 Privately-held debt and redeemable preferred stock securities 14.6 37.4 — 52.0 16.6 37.4 — 54.0 Total available-for-sale debt securities $ 1,776.1 $ 37.5 $ (1.9 ) $ 1,811.7 $ 2,223.6 $ 37.4 $ (4.2 ) $ 2,256.8 Reported as: Cash equivalents $ 414.4 $ — $ — $ 414.4 $ 936.5 $ — $ — $ 936.5 Short-term investments 1,226.7 0.1 (1.2 ) 1,225.6 1,069.2 — (1.9 ) 1,067.3 Long-term investments 120.4 — (0.7 ) 119.7 201.3 — (2.3 ) 199.0 Other long-term assets 14.6 37.4 — 52.0 16.6 37.4 — 54.0 Total $ 1,776.1 $ 37.5 $ (1.9 ) $ 1,811.7 $ 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 March 31, 2019 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,641.1 $ 1,640.0 Due between one and five years 120.4 119.7 Total $ 1,761.5 $ 1,759.7
Available-for-sale securities in unrealized loss position	The following tables present the Company's total fixed income securities that were in an unrealized loss position as of March 31, 2019 and December 31, 2018 (in millions): As of March 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 $ 0.2 $ — $ 27.7 $ (0.1 ) $ 27.9 $ (0.1 ) Corporate debt securities 47.3 — 278.1 (1.3 ) 325.4 (1.3 ) Foreign government debt securities 5.5 — 17.3 (0.1 ) 22.8 (0.1 ) U.S. government agency securities — — 23.6 (0.1 ) 23.6 (0.1 ) U.S. government securities 312.0 — 46.4 (0.3 ) 358.4 (0.3 ) Total fixed income securities $ 365.0 $ — $ 393.1 $ (1.9 ) $ 758.1 $ (1.9 ) 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 March 31, 2019 and December 31, 2018 (in millions): As of March 31, December 31, Equity investments with readily determinable fair value Money market funds (1) $ 836.7 $ 996.9 Mutual funds (2) 26.2 24.3 Publicly-traded equity securities 1.8 2.8 Equity investments without readily determinable fair value 42.1 36.4 Total equity securities $ 906.8 $ 1,060.4 Reported as: Cash equivalents $ 825.1 $ 985.3 Short-term investments 1.8 2.8 Prepaid expenses and other current assets 11.2 10.9 Other long-term assets 68.7 61.4 Total $ 906.8 $ 1,060.4 ________________________________ (1) Balance includes $11.6 million and $11.6 million in restricted investments measured at fair value, related to the Company's acquisition-related escrow accounts as of March 31, 2019 and December 31, 2018 , respectively. (2) Balance relates to restricted investments measured at fair value related to the Company's Deferred Compensation Plan.
Schedule of reconciliation of cash, cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash included in the Condensed Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 (in millions): As of March 31, December 31, Cash and cash equivalents $ 2,155.6 $ 2,489.0 Restricted cash included in Prepaid expenses and other current assets 17.5 16.8 Total cash, cash equivalents, and restricted cash $ 2,173.1 $ 2,505.8

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 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 Condensed 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 $ — $ 30.3 $ — $ 30.3 $ — $ 46.5 $ — $ 46.5 Certificates of deposit — 95.4 — 95.4 — 152.9 — 152.9 Commercial paper — 377.5 — 377.5 — 393.6 — 393.6 Corporate debt securities — 362.0 — 362.0 — 413.0 — 413.0 Foreign government debt securities — 38.3 — 38.3 — 19.9 — 19.9 Time deposits — 84.2 — 84.2 — 278.6 — 278.6 U.S. government agency securities — 25.6 — 25.6 — 87.0 — 87.0 U.S. government securities 412.9 333.5 — 746.4 352.8 458.5 — 811.3 Privately-held debt and redeemable preferred stock securities — — 52.0 52.0 — — 54.0 54.0 Total available-for-sale debt securities 412.9 1,346.8 52.0 1,811.7 352.8 1,850.0 54.0 2,256.8 Equity securities: Money market funds 836.7 — — 836.7 996.9 — — 996.9 Mutual funds 26.2 — — 26.2 24.3 — — 24.3 Publicly-traded equity securities 1.8 — — 1.8 2.8 — — 2.8 Total equity securities 864.7 — — 864.7 1,024.0 — — 1,024.0 Derivative assets: Foreign exchange contracts — 8.4 — 8.4 — 5.3 — 5.3 Total assets measured at fair value $ 1,277.6 $ 1,355.2 $ 52.0 $ 2,684.8 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Liabilities: Derivative liabilities: Foreign exchange contracts $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total liabilities measured at fair value $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total assets, reported as: Cash equivalents $ 825.1 $ 414.4 $ — $ 1,239.5 $ 1,025.2 $ 896.6 $ — $ 1,921.8 Short-term investments 406.2 821.2 — 1,227.4 297.5 772.6 — 1,070.1 Long-term investments 8.5 111.2 — 119.7 18.2 180.8 — 199.0 Prepaid expenses and other current assets 11.3 8.4 — 19.7 10.8 5.3 — 16.1 Other long-term assets 26.5 — 52.0 78.5 25.1 — 54.0 79.1 Total assets measured at fair value $ 1,277.6 $ 1,355.2 $ 52.0 $ 2,684.8 $ 1,376.8 $ 1,855.3 $ 54.0 $ 3,286.1 Total liabilities, reported as: Other accrued liabilities $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 ) Total liabilities measured at fair value $ — $ (5.8 ) $ — $ (5.8 ) $ — $ (7.1 ) $ — $ (7.1 )

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions): As of March 31, December 31, Cash flow hedges $ 377.0 $ 497.7 Non-designated derivatives 175.6 158.7 Total $ 552.6 $ 656.4

Other Financial Information (Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2019
Other Financial Information [Abstract]
Inventories	Total inventory consisted of the following (in millions): As of March 31, December 31, Production and service materials $ 72.6 $ 60.6 Finished goods 21.3 21.4 Inventory $ 93.9 $ 82.0 Reported as: Prepaid expenses and other current assets $ 92.4 $ 80.6 Other long-term assets 1.5 1.4 Total $ 93.9 $ 82.0
Warranties	Changes during the three months ended March 31, 2019 in the Company’s warranty reserve as reported within other accrued liabilities in the Condensed Consolidated Balance Sheets were as follows (in millions): Balance as of December 31, 2018 $ 28.0 Provisions made during the period 8.6 Actual costs incurred during the period (7.7 ) Balance as of March 31, 2019 $ 28.9
Deferred revenue	Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions): As of March 31, December 31, Deferred product revenue: Undelivered product commitments and other product deferrals $ 152.3 $ 163.3 Deferred gross product revenue 152.3 163.3 Deferred cost of product revenue (12.7 ) (18.9 ) Deferred product revenue, net 139.6 144.4 Deferred service revenue 1,091.3 1,069.2 Total $ 1,230.9 $ 1,213.6 Reported as: Current $ 860.1 $ 829.3 Long-term 370.8 384.3 Total $ 1,230.9 $ 1,213.6
Performance obligation	The following table summarizes the transaction price for contracts that have not yet been recognized as revenue as of March 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 $ 152.3 $ 122.8 $ 26.0 $ 3.5 Service 1,091.3 750.0 285.8 55.5 Total $ 1,243.6 $ 872.8 $ 311.8 $ 59.0
Other income (expense), net	Other income (expense), net, consisted of the following (in millions): Three Months Ended March 31, 2019 2018 Interest income $ 23.5 $ 14.9 Interest expense (24.2 ) (26.0 ) Gain (loss) on investments, net 1.6 (0.5 ) Other 0.9 (2.5 ) Other income (expense), net $ 1.8 $ (14.1 )

Restructuring (Benefits) Charge

Restructuring (Benefits) Charges (Tables)	3 Months Ended
	Mar. 31, 2019
Restructuring and Related Activities [Abstract]
Schedule of restructuring liabilities	The following table provides a summary of changes in the restructuring liabilities for the Company's 2019 and prior year plans (in millions): December 31, Charges Cash Payments Other March 31, Severance $ 1.1 $ 15.1 $ (10.1 ) $ (0.1 ) $ 6.0 Facility consolidations — 0.2 (0.1 ) (0.1 ) — Total $ 1.1 $ 15.3 $ (10.2 ) $ (0.2 ) $ 6.0

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Summary of dividends paid and stock repurchases and retirements under stock repurchase program	The following table summarizes dividends paid, stock repurchases and retirements under the Company's stock repurchase program (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 (1)(2) Dividends Per share $ 0.19 $ 0.18 Amount $ 66.2 $ 62.1 Stock repurchases Shares — 23.3 Average price per share $ — $ 25.80 Amount $ — $ 750.0 ________________________________ (1) Shares repurchased under the 2018 Stock Repurchase Program. (2) $750.0 million represents the full amount of the accelerated share repurchase program (the "ASR") for which 23.3 million shares were received initially during the first quarter of 2018, and an additional 6.0 million shares were received at final settlement during the third quarter of 2018.
Components of accumulated other comprehensive loss, net of taxes	The components of accumulated other comprehensive loss, net of related taxes, for the three months ended March 31, 2019 were as follows (in millions): Unrealized Gains/Losses on Available-for- Sale Debt Securities Unrealized Gains/Losses on Cash Flow Hedges Foreign Currency Translation Adjustments Total Balance as of December 31, 2018 $ 25.5 $ (0.9 ) $ (42.8 ) $ (18.2 ) Other comprehensive income before reclassifications 1.8 2.1 2.2 6.1 Amount reclassified from accumulated other comprehensive loss — 1.2 — 1.2 Other comprehensive income, net 1.8 3.3 2.2 7.3 Balance as of March 31, 2019 $ 27.3 $ 2.4 $ (40.6 ) $ (10.9 )

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of nonvested share activity	The Company’s RSU and PSA activity and related information as of and for the three months ended March 31, 2019 were as follows (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 as of December 31, 2018 17.4 $ 25.32 RSUs granted (1)(3) 5.5 25.53 PSAs granted (2)(3) 0.7 25.06 RSUs vested (3.9 ) 26.00 RSAs vested (0.1 ) 23.13 PSAs vested (0.5 ) 26.76 RSUs canceled (0.8 ) 26.32 PSAs canceled (0.6 ) 23.25 Balance as of March 31, 2019 17.7 $ 25.21 1.5 $ 467.8 ________________________________ (1) Includes service-based and market-based RSUs. The number of shares subject to market-based condition 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 market-based condition that would be issued if market criteria determined by the Compensation Committee of the Board are achieved at target is 0.2 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 0.4 million shares. (2) 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 these PSAs that would be issued if performance goals determined by the Compensation Committee of the Board are achieved at target is 0.4 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is zero to 0.7 million shares. (3) The grant date fair value of RSUs and PSAs were 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 the three months ended March 31, 2019 , the Company declared a quarterly cash dividend of $0.19 per share of common stock on January 29, 2019. (4) 0.3 million shares of PSAs were modified during the three months ended March 31, 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 $7.7 million to be recognized over the remaining terms of the modified awards.
Summary of employee stock purchases through the ESPP	The following table summarizes employee stock purchases through the ESPP (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 Shares purchased 1.2 1.3 Average exercise price per share $ 22.04 $ 22.23
Schedule of employee service share-based compensation, allocation of recognized period costs	Share-based compensation expense associated with stock options, RSUs, restricted stock awards ("RSAs"), PSAs, and the ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions): Three Months Ended March 31, 2019 2018 Cost of revenues - Product $ 1.9 $ 1.9 Cost of revenues - Service 4.5 4.8 Research and development 12.2 44.1 Sales and marketing 9.4 13.5 General and administrative 5.9 6.1 Total $ 33.9 $ 70.4
Disclosure of share-based compensation arrangements by share-based payment award	The following table summarizes share-based compensation expense by award type (in millions): Three Months Ended March 31, 2019 2018 Stock options $ 0.1 $ 0.1 RSUs, RSAs, and PSAs 29.1 65.6 ESPP 4.7 4.7 Total $ 33.9 $ 70.4

Segments (Tables)

Segments (Tables)	3 Months Ended
	Mar. 31, 2019
Segment Reporting [Abstract]
Financial information for each segment	The following table presents net revenues by product and service (in millions): Three Months Ended March 31, 2019 2018 Routing $ 374.7 $ 408.1 Switching 176.4 230.0 Security 67.6 72.7 Total product 618.7 710.8 Total service 383.0 371.8 Total $ 1,001.7 $ 1,082.6 The following table presents net revenues by customer vertical (*) (in millions): Three Months Ended March 31, 2019 2018 Cloud $ 223.1 $ 270.9 Service Provider 435.6 480.1 Enterprise 343.0 331.6 Total $ 1,001.7 $ 1,082.6 ________________________________ (*) Certain insignificant prior-period amounts have been reclassified to conform to the current-period presentation.
Disaggregation of revenue	The following table presents net revenues by product and service (in millions): Three Months Ended March 31, 2019 2018 Routing $ 374.7 $ 408.1 Switching 176.4 230.0 Security 67.6 72.7 Total product 618.7 710.8 Total service 383.0 371.8 Total $ 1,001.7 $ 1,082.6 The following table presents net revenues by customer vertical (*) (in millions): Three Months Ended March 31, 2019 2018 Cloud $ 223.1 $ 270.9 Service Provider 435.6 480.1 Enterprise 343.0 331.6 Total $ 1,001.7 $ 1,082.6 ________________________________ (*) Certain insignificant prior-period amounts have been reclassified to conform to the current-period presentation. The Company attributes revenues to geographic region based on the customer’s shipping address. The following table presents net revenues by geographic region (in millions): Three Months Ended March 31, 2019 2018 Americas: United States $ 476.6 $ 532.3 Other 67.0 55.3 Total Americas 543.6 587.6 Europe, Middle East, and Africa 286.2 308.0 Asia Pacific 171.9 187.0 Total $ 1,001.7 $ 1,082.6
Net revenues by geographic region	The Company attributes revenues to geographic region based on the customer’s shipping address. The following table presents net revenues by geographic region (in millions): Three Months Ended March 31, 2019 2018 Americas: United States $ 476.6 $ 532.3 Other 67.0 55.3 Total Americas 543.6 587.6 Europe, Middle East, and Africa 286.2 308.0 Asia Pacific 171.9 187.0 Total $ 1,001.7 $ 1,082.6

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of effective income tax rate reconciliation	The following table provides details of income taxes (in millions, except percentages): Three Months Ended March 31, 2019 2018 Income before income taxes $ 44.5 $ 41.4 Income tax provision $ 13.4 $ 7.0 Effective tax rate 30.1 % 16.9 %

Net Income Per Share (Tables)

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of basic and diluted net income per share	The Company computed basic and diluted net income per share as follows (in millions, except per share amounts): Three Months Ended March 31, 2019 2018 Numerator: Net income $ 31.1 $ 34.4 Denominator: Weighted-average shares used to compute basic net income per share 348.1 355.3 Dilutive effect of employee stock awards 4.6 5.3 Weighted-average shares used to compute diluted net income per share 352.7 360.6 Net income per share Basic $ 0.09 $ 0.10 Diluted $ 0.09 $ 0.10 Anti-dilutive shares 5.0 10.4

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Components of lease costs and other information related to leases	The components of lease costs and other information related to leases were as follows (in millions, except years and percentages): Three Months Ended March 31, 2019 Operating lease cost $ 11.9 Variable lease cost 3.1 Total lease cost $ 15.0 Operating cash outflows from operating leases $ 11.6 ROU assets obtained in exchange for new operating lease liabilities $ 0.6 Weighted average remaining lease term (years) 6.0 Weighted average discount rate 4.4 %
Future minimum operating lease payments	As of March 31, 2019 , future minimum operating lease payments for each of the next five years and thereafter is as follows (in millions): Years Ending December 31, Amount 2019 $ 32.9 2020 47.3 2021 40.4 2022 32.7 2023 29.8 Thereafter 60.3 Total lease payments 243.4 Less: interest (30.0 ) Total $ 213.4 Balance Sheet Information Other accrued liabilities 36.7 Long-term operating lease liabilities 176.7 Total $ 213.4
Supplemental balance sheet information related to leases	As of March 31, 2019 , future minimum operating lease payments for each of the next five years and thereafter is as follows (in millions): Years Ending December 31, Amount 2019 $ 32.9 2020 47.3 2021 40.4 2022 32.7 2023 29.8 Thereafter 60.3 Total lease payments 243.4 Less: interest (30.0 ) Total $ 213.4 Balance Sheet Information Other accrued liabilities 36.7 Long-term operating lease liabilities 176.7 Total $ 213.4

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Cumulative Effect of Adjustments to the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets:
Prepaid expenses and other current assets	$ 281.2	$ 266.7	$ 268.1
Property and equipment, net	892.4	908.8	951.7
Operating lease assets	184.2	192.5
Other long-term assets	409.2	404.8	403.5
Total assets	9,137.9	9,512.8	9,363.3
Liabilities:
Other accrued liabilities	243.1	269.1	233.5
Long-term operating lease liabilities	176.7	185.5
Other long-term liabilities	53.2	53.1	119.8
Total liabilities	4,286.7	4,694.5	4,540.1
Stockholders' Equity:
Accumulated deficit	$ 2,806.5	2,836.3	$ 2,831.4
Accounting Standards Update 2016-02
Assets:
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
Liabilities:
Other accrued liabilities		35.6
Long-term operating lease liabilities		185.5
Other long-term liabilities		(66.7)
Total liabilities		154.4
Stockholders' Equity:
Accumulated deficit		$ 4.9

Cash Equivalents and Investme_3

Cash Equivalents and Investments - Available-For-Sale (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale debt securities:
Amortized Cost	$ 1,776.1	$ 2,223.6
Gross Unrealized Gains	37.5	37.4
Gross Unrealized Losses	(1.9)	(4.2)
Estimated Fair Value	1,811.7	2,256.8
Asset-backed securities
Available-for-sale debt securities:
Amortized Cost	30.4	46.8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.1)	(0.3)
Estimated Fair Value	30.3	46.5
Certificates of deposit
Available-for-sale debt securities:
Amortized Cost	95.4	152.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	95.4	152.9
Commercial paper
Available-for-sale debt securities:
Amortized Cost	377.5	393.6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	377.5	393.6
Corporate debt securities
Available-for-sale debt securities:
Amortized Cost	363.3	416.1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1.3)	(3.1)
Estimated Fair Value	362	413
Foreign government debt securities
Available-for-sale debt securities:
Amortized Cost	38.4	20
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.1)	(0.1)
Estimated Fair Value	38.3	19.9
Time deposits
Available-for-sale debt securities:
Amortized Cost	84.2	278.6
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	84.2	278.6
U.S. government agency securities
Available-for-sale debt securities:
Amortized Cost	25.7	87.2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.1)	(0.2)
Estimated Fair Value	25.6	87
U.S. government securities
Available-for-sale debt securities:
Amortized Cost	746.6	811.8
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	(0.3)	(0.5)
Estimated Fair Value	746.4	811.3
Fixed Income securities
Available-for-sale debt securities:
Amortized Cost	1,761.5	2,207
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	(1.9)	(4.2)
Estimated Fair Value	1,759.7	2,202.8
Privately-held debt and redeemable preferred stock securities
Available-for-sale debt securities:
Amortized Cost	14.6	16.6
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0	0
Estimated Fair Value	52	54
Cash equivalents
Available-for-sale debt securities:
Amortized Cost	414.4	936.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	414.4	936.5
Short-term investments
Available-for-sale debt securities:
Amortized Cost	1,226.7	1,069.2
Gross Unrealized Gains	0.1	0
Gross Unrealized Losses	(1.2)	(1.9)
Estimated Fair Value	1,225.6	1,067.3
Long-term investments
Available-for-sale debt securities:
Amortized Cost	120.4	201.3
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.7)	(2.3)
Estimated Fair Value	119.7	199
Other long-term assets
Available-for-sale debt securities:
Amortized Cost	14.6	16.6
Gross Unrealized Gains	37.4	37.4
Gross Unrealized Losses	0	0
Estimated Fair Value	$ 52	$ 54

Cash Equivalents and Investme_4

Cash Equivalents and Investments - Maturities of Fixed Income Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Amortized Cost
Amortized Cost	$ 1,776.1	$ 2,223.6
Estimated Fair Value
Total	1,811.7	2,256.8
Fixed Income Securities
Amortized Cost
Due in less than one year	1,641.1
Due between one and five years	120.4
Amortized Cost	1,761.5	2,207
Estimated Fair Value
Due in less than one year	1,640
Due between one and five years	119.7
Total	$ 1,759.7	$ 2,202.8

Cash Equivalents and Investme_5

Cash Equivalents and Investments - Unrealized Loss Position on Fixed Income Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value
Less than 12 Months	$ 365	$ 423.2
12 Months or Greater	393.1	500.8
Total	758.1	924
Unrealized Loss
Less than 12 Months	0	(0.1)
12 Months or Greater	(1.9)	(4.1)
Total	(1.9)	(4.2)
Asset-backed securities
Fair Value
Less than 12 Months	0.2	3.1
12 Months or Greater	27.7	43
Total	27.9	46.1
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	(0.1)	(0.3)
Total	(0.1)	(0.3)
Corporate debt securities
Fair Value
Less than 12 Months	47.3	72.6
12 Months or Greater	278.1	330.7
Total	325.4	403.3
Unrealized Loss
Less than 12 Months	0	(0.1)
12 Months or Greater	(1.3)	(3)
Total	(1.3)	(3.1)
Foreign government debt securities
Fair Value
Less than 12 Months	5.5	1.5
12 Months or Greater	17.3	18.4
Total	22.8	19.9
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	(0.1)	(0.1)
Total	(0.1)	(0.1)
U.S. government agency securities
Fair Value
Less than 12 Months	0	2
12 Months or Greater	23.6	45.2
Total	23.6	47.2
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	(0.1)	(0.2)
Total	(0.1)	(0.2)
U.S. government securities
Fair Value
Less than 12 Months	312	344
12 Months or Greater	46.4	63.5
Total	358.4	407.5
Unrealized Loss
Less than 12 Months	0	0
12 Months or Greater	(0.3)	(0.5)
Total	$ (0.3)	$ (0.5)

Cash Equivalents and Investme_6

Cash Equivalents and Investments - Narrative (Details)	3 Months Ended
	Mar. 31, 2019USD ($)Investment	Mar. 31, 2018USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Total investments in unrealized loss position | Investment	382
Available-for-sale debt securities, gross realized gain	$ 0	$ 0
Available-for-sale debt securities, gross realized loss	0	0
Equity investments, unrealized gains	0	0
Equity investments, unrealized losses	0	0
Restricted cash and investments	55,300,000
Prepaid expenses and other current assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	28,800,000
Other long-term assets
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	26,500,000
Debt Securities
Restricted Cash and Cash Equivalents Items [Line Items]
OTTI, associated with credit losses	$ 0	$ 0

Cash Equivalents and Investme_7

Cash Equivalents and Investments - Investments in Equity Securities (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments without readily determinable fair value	$ 42.1
Total equity securities	906.8
Equity investments without readily determinable fair value		$ 36.4
Total equity securities		1,060.4
Acquisition-related escrows	11.6	11.6
Cash equivalents
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	825.1
Total equity securities		985.3
Short-term investments
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	1.8
Total equity securities		2.8
Prepaid expenses and other current assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	11.2
Total equity securities		10.9
Other long-term assets
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Total equity securities	68.7
Total equity securities		61.4
Money market funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	836.7
Equity investments with readily determinable fair value		996.9
Mutual funds
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	26.2
Equity investments with readily determinable fair value		24.3
Publicly-traded equity securities
Debt Securities, Trading, and Equity Securities, FV-NI [Line Items]
Equity investments with readily determinable fair value	$ 1.8
Equity investments with readily determinable fair value		$ 2.8

Cash Equivalents and Investme_8

Cash Equivalents and Investments - Cash and Cash Equivalents (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash Equivalents and Investments [Abstract]
Cash and cash equivalents	$ 2,155.6	$ 2,489
Restricted cash	17.5	16.8
Total cash, cash equivalents, and restricted cash	$ 2,173.1	$ 2,505.8	$ 2,645	$ 2,059.1

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Available-for-sale securities:
Available-for-sale debt securities	$ 1,811.7	$ 2,256.8
Asset-backed securities
Available-for-sale securities:
Available-for-sale debt securities	30.3	46.5
Certificates of deposit
Available-for-sale securities:
Available-for-sale debt securities	95.4	152.9
Commercial paper
Available-for-sale securities:
Available-for-sale debt securities	377.5	393.6
Corporate debt securities
Available-for-sale securities:
Available-for-sale debt securities	362	413
Foreign government debt securities
Available-for-sale securities:
Available-for-sale debt securities	38.3	19.9
Time deposits
Available-for-sale securities:
Available-for-sale debt securities	84.2	278.6
U.S. government agency securities
Available-for-sale securities:
Available-for-sale debt securities	25.6	87
U.S. government securities
Available-for-sale securities:
Available-for-sale debt securities	746.4	811.3
Privately-held debt and redeemable preferred stock securities
Available-for-sale securities:
Available-for-sale debt securities	52	54
Money market funds
Available-for-sale securities:
Equity securities	836.7
Equity securities		996.9
Publicly-traded equity securities
Available-for-sale securities:
Equity securities	1.8
Equity securities		2.8
Fair Value, Measurements, Recurring
Available-for-sale securities:
Equity securities	864.7
Equity securities		1,024
Derivative assets:
Total assets measured at fair value	2,684.8	3,286.1
Liabilities measured at fair value:
Total liabilities measured at fair value	(5.8)	(7.1)
Fair Value, Measurements, Recurring | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	8.4	5.3
Liabilities measured at fair value:
Derivative liabilities	(5.8)	(7.1)
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Equity securities	864.7
Equity securities		1,024
Derivative assets:
Total assets measured at fair value	1,277.6	1,376.8
Liabilities measured at fair value:
Total liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1) | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Derivative assets:
Total assets measured at fair value	1,355.2	1,855.3
Liabilities measured at fair value:
Total liabilities measured at fair value	(5.8)	(7.1)
Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2) | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	8.4	5.3
Liabilities measured at fair value:
Derivative liabilities	(5.8)	(7.1)
Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Derivative assets:
Total assets measured at fair value	52	54
Liabilities measured at fair value:
Total liabilities measured at fair value	0	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3) | Foreign exchange contracts
Derivative assets:
Foreign exchange contracts	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Asset-backed securities
Available-for-sale securities:
Available-for-sale debt securities	30.3	46.5
Fair Value, Measurements, Recurring | Asset-backed securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Asset-backed securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	30.3	46.5
Fair Value, Measurements, Recurring | Asset-backed securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Certificates of deposit
Available-for-sale securities:
Available-for-sale debt securities	95.4	152.9
Fair Value, Measurements, Recurring | Certificates of deposit | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Certificates of deposit | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	95.4	152.9
Fair Value, Measurements, Recurring | Certificates of deposit | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Commercial paper
Available-for-sale securities:
Available-for-sale debt securities	377.5	393.6
Fair Value, Measurements, Recurring | Commercial paper | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Commercial paper | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	377.5	393.6
Fair Value, Measurements, Recurring | Commercial paper | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Corporate debt securities
Available-for-sale securities:
Available-for-sale debt securities	362	413
Fair Value, Measurements, Recurring | Corporate debt securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	362	413
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Foreign government debt securities
Available-for-sale securities:
Available-for-sale debt securities	38.3	19.9
Fair Value, Measurements, Recurring | Foreign government debt securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Foreign government debt securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	38.3	19.9
Fair Value, Measurements, Recurring | Foreign government debt securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Time deposits
Available-for-sale securities:
Available-for-sale debt securities	84.2	278.6
Fair Value, Measurements, Recurring | Time deposits | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Time deposits | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	84.2	278.6
Fair Value, Measurements, Recurring | Time deposits | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | U.S. government agency securities
Available-for-sale securities:
Available-for-sale debt securities	25.6	87
Fair Value, Measurements, Recurring | U.S. government agency securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | U.S. government agency securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	25.6	87
Fair Value, Measurements, Recurring | U.S. government agency securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | U.S. government securities
Available-for-sale securities:
Available-for-sale debt securities	746.4	811.3
Fair Value, Measurements, Recurring | U.S. government securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	412.9	352.8
Fair Value, Measurements, Recurring | U.S. government securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	333.5	458.5
Fair Value, Measurements, Recurring | U.S. government securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities
Available-for-sale securities:
Available-for-sale debt securities	52	54
Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	0	0
Fair Value, Measurements, Recurring | Privately-held debt and redeemable preferred stock securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	52	54
Fair Value, Measurements, Recurring | Total available-for-sale debt securities
Available-for-sale securities:
Available-for-sale debt securities	1,811.7	2,256.8
Fair Value, Measurements, Recurring | Total available-for-sale debt securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Available-for-sale debt securities	412.9	352.8
Fair Value, Measurements, Recurring | Total available-for-sale debt securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Available-for-sale debt securities	1,346.8	1,850
Fair Value, Measurements, Recurring | Total available-for-sale debt securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Available-for-sale debt securities	52	54
Fair Value, Measurements, Recurring | Money market funds
Available-for-sale securities:
Equity securities	836.7
Equity securities		996.9
Fair Value, Measurements, Recurring | Money market funds | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Equity securities	836.7
Equity securities		996.9
Fair Value, Measurements, Recurring | Money market funds | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Fair Value, Measurements, Recurring | Money market funds | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Fair Value, Measurements, Recurring | Mutual funds
Available-for-sale securities:
Equity securities	26.2
Equity securities		24.3
Fair Value, Measurements, Recurring | Mutual funds | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Equity securities	26.2
Equity securities		24.3
Fair Value, Measurements, Recurring | Mutual funds | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Fair Value, Measurements, Recurring | Mutual funds | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Fair Value, Measurements, Recurring | Publicly-traded equity securities
Available-for-sale securities:
Equity securities	1.8
Equity securities		2.8
Fair Value, Measurements, Recurring | Publicly-traded equity securities | Quoted Prices in Active Markets For Identical Assets (Level 1)
Available-for-sale securities:
Equity securities	1.8
Equity securities		2.8
Fair Value, Measurements, Recurring | Publicly-traded equity securities | Significant Other Observable Remaining Inputs (Level 2)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Fair Value, Measurements, Recurring | Publicly-traded equity securities | Significant Other Unobservable Remaining Inputs (Level 3)
Available-for-sale securities:
Equity securities	0
Equity securities		0
Cash equivalents
Available-for-sale securities:
Available-for-sale debt securities	414.4	936.5
Cash equivalents | Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value	1,239.5	1,921.8
Cash equivalents | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value	825.1	1,025.2
Cash equivalents | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value	414.4	896.6
Cash equivalents | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value	0	0
Short-term investments
Available-for-sale securities:
Available-for-sale debt securities	1,225.6	1,067.3
Short-term investments | Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value	1,227.4	1,070.1
Short-term investments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value	406.2	297.5
Short-term investments | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value	821.2	772.6
Short-term investments | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value	0	0
Long-term investments
Available-for-sale securities:
Available-for-sale debt securities	119.7	199
Long-term investments | Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value	119.7	199
Long-term investments | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value	8.5	18.2
Long-term investments | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value	111.2	180.8
Long-term investments | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value	0	0
Prepaid expenses and other current assets | Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value	19.7	16.1
Prepaid expenses and other current assets | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value	11.3	10.8
Prepaid expenses and other current assets | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value	8.4	5.3
Prepaid expenses and other current assets | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value	0	0
Other long-term assets | Fair Value, Measurements, Recurring
Derivative assets:
Total assets measured at fair value	78.5	79.1
Other long-term assets | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Derivative assets:
Total assets measured at fair value	26.5	25.1
Other long-term assets | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Derivative assets:
Total assets measured at fair value	0	0
Other long-term assets | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Derivative assets:
Total assets measured at fair value	52	54
Other accrued liabilities | Fair Value, Measurements, Recurring
Liabilities measured at fair value:
Total liabilities measured at fair value	(5.8)	(7.1)
Other accrued liabilities | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets For Identical Assets (Level 1)
Liabilities measured at fair value:
Total liabilities measured at fair value	0	0
Other accrued liabilities | Fair Value, Measurements, Recurring | Significant Other Observable Remaining Inputs (Level 2)
Liabilities measured at fair value:
Total liabilities measured at fair value	(5.8)	(7.1)
Other accrued liabilities | Fair Value, Measurements, Recurring | Significant Other Unobservable Remaining Inputs (Level 3)
Liabilities measured at fair value:
Total liabilities measured at fair value	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill and intangible impairment	$ 0
Equity securities without readily determinable fair value, impairment	0
Equity securities without readily determinable fair value, upward adjustment	0
Equity securities without readily determinable fair value, downward adjustment	0
Contract manufacturer deposit (non-interest bearing)	47,600,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	5,800,000	$ 7,100,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	0	0
Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	0	0
Significant Other Observable Remaining Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and long-term debt, fair value	1,856,200,000	2,158,700,000
Significant Other Observable Remaining Inputs (Level 2) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and nonfinancial liabilities, fair value disclosure	5,800,000	7,100,000
Privately-held debt and redeemable preferred stock securities | Significant Other Unobservable Remaining Inputs (Level 3) | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized gain (loss) on investments	0
Junos Pulse
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note receivable	$ 69,000,000	$ 69,000,000

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivatives, Notional Amount [Line Items]
Notional amount of foreign currency derivatives	$ 552.6		$ 656.4
Changes in fiar value of non-designated derivatives	0	$ 0
Non-designated derivatives
Derivatives, Notional Amount [Line Items]
Notional amount of foreign currency derivatives	175.6		158.7
Cash flow hedges | Designated as hedge
Derivatives, Notional Amount [Line Items]
Notional amount of foreign currency derivatives	$ 377		$ 497.7
Maturities of cash flow hedge derivatives	18 months
Losses expected to be reclassified into earnings within the next 12 months	$ 2.8
Foreign exchange contracts | Cash flow hedges
Derivatives, Notional Amount [Line Items]
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	3.4	13.4
Cost of revenues and operating expenses | Foreign exchange contracts | Cash flow hedges
Derivatives, Notional Amount [Line Items]
Gain (loss) reclassified	$ (1)	$ 5.6

Other Financial Information - I

Other Financial Information - Inventories, Net (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Inventory [Line Items]
Production and service materials	$ 72.6	$ 60.6
Finished goods	21.3	21.4
Inventory	93.9	82
Prepaid expenses and other current assets
Schedule Of Inventory [Line Items]
Inventory	92.4	80.6
Other long-term assets
Schedule Of Inventory [Line Items]
Inventory	$ 1.5	$ 1.4

Other Financial Information - N

Other Financial Information - Narrative (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Other Financial Information [Abstract]
Contract manufacturer deposit (non-interest bearing)	$ 47,600,000
Non-interest bearing deposit to contract manufacturer, unamortized discount	$ 2,300,000
Non-interest bearing deposit to contract manufacturer, imputed interest rate	4.80%
Deferred commission	$ 26,100,000
Amortization of deferred commission	34,900,000
Impairment loss	$ 0

Other Financial Information - W

Other Financial Information - Warranties (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance as of December 31, 2018	$ 28
Provisions made during the period	8.6
Actual costs incurred during the period	(7.7)
Balance as of March 31, 2019	$ 28.9

Other Financial Information - D

Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Reported as:
Current	$ 860.1	$ 829.3
Long-term	370.8	384.3
Deferred revenue	1,230.9	1,213.6
Undelivered product commitments and other product deferrals
Deferred product revenue:
Deferred gross product revenue	152.3	163.3
Product
Deferred product revenue:
Deferred gross product revenue	152.3	163.3
Deferred cost of product revenue	(12.7)	(18.9)
Reported as:
Deferred revenue	139.6	144.4
Service
Reported as:
Deferred revenue	$ 1,091.3	$ 1,069.2

Other Financial Information - R

Other Financial Information - Revenue (Details) $ in Millions	Mar. 31, 2019USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 872.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01 | Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 122.8
Revenue recognition expected by period, satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-04-01 | Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 750
Revenue recognition expected by period, satisfaction period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 311.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 26
Revenue recognition expected by period, satisfaction period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 285.8
Revenue recognition expected by period, satisfaction period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 59
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 3.5
Revenue recognition expected by period, satisfaction period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 55.5
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	$ 1,243.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Product
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	152.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Service
Disaggregation of Revenue [Line Items]
Revenue recognition expected by period	$ 1,091.3

Other Financial Information - O

Other Financial Information - Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Other Financial Information [Abstract]
Interest income	$ 23.5	$ 14.9
Interest expense	(24.2)	(26)
Gain (loss) on investments, net	1.6	(0.5)
Other	0.9	(2.5)
Other income (expense), net	$ 1.8	$ (14.1)

Restructuring Charges - Narrati

Restructuring Charges - Narrative (Details) - 2019 Restructuring Plan $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Restructuring Cost and Reserve [Line Items]
Severance costs	$ 15.1
Facility consolidations	$ 0.2

Restructuring Charges - Changes

Restructuring Charges - Changes to Restructuring Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Restructuring Reserve [Roll Forward]
Charges/ (Benefits)	$ 15.3	$ (1.9)
2019 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	15.3
Cash Payments	(10.2)
Other	(0.2)
Restructuring liability, ending balance	6
2019 Restructuring Plan | Severance
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	1.1
Charges/ (Benefits)	15.1
Cash Payments	(10.1)
Other	(0.1)
Restructuring liability, ending balance	6
2019 Restructuring Plan | Facility consolidations
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0
Charges/ (Benefits)	0.2
Cash Payments	(0.1)
Other	(0.1)
Restructuring liability, ending balance	$ 0

Equity - Summary of Dividends

Equity - Summary of Dividends Paid and Stock Repurchases and Reitrements (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Mar. 22, 2019	Jan. 29, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Sep. 30, 2018
Dividends
Per share (in dollars per share)	$ 0.19		$ 0.19		$ 0.18
Per share, declared (in dollars per share)		$ 0.19	$ 0.19		$ 0.18
Amount			$ 66.2		$ 62.1
Stock repurchases
Amount			2.9		604.2
Repurchase and retirement of common stock			$ 2.9		$ 754.2
Stock Repurchase Program 2018
Stock repurchases
Shares (in shares)			0		23.3
Average price per share (in dollars per share)			$ 0		$ 25.80
Amount			$ 0		$ 750
Shares received (in shares)			0		23.3
Accelerated Share Repurchase Program
Stock repurchases
Shares (in shares)			29.3	6	23.3
Average price per share (in dollars per share)			$ 25.62
Repurchase and retirement of common stock						$ 750
Shares received (in shares)			29.3	6	23.3

Equity - Cash Dividends on Sha

Equity - Cash Dividends on Shares of Common Stock (Details) - $ / shares	Mar. 22, 2019	Jan. 29, 2019	Mar. 31, 2019	Mar. 31, 2018
Stockholders' Equity Note [Abstract]
Cash dividends declared per share of common stock (in dollars per share)		$ 0.19	$ 0.19	$ 0.18
Cash dividends paid per share of common stock (in dollars per share)	$ 0.19		$ 0.19	$ 0.18

Equity - Stock Repurchase Acti

Equity - Stock Repurchase Activities (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended			9 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Sep. 30, 2018	Feb. 28, 2018	Jan. 31, 2018
Accelerated Share Repurchases [Line Items]
Payment to repurchase stock	$ 2,900,000		$ 754,200,000
Stock Repurchase Program 2018
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount						$ 2,000,000,000
Stock repurchased and retired (in shares)	0		23.3
Average price per share (in dollars per share)	$ 0		$ 25.80
Stock repurchase program, remaining authorized repurchase amount	$ 1,300,000,000
Accelerated Share Repurchase Program
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount					$ 750,000,000
Payment to repurchase stock				$ 750,000,000
Stock repurchased and retired (in shares)	29.3	6	23.3
Average price per share (in dollars per share)	$ 25.62

Equity - Components of Accumul

Equity - Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	$ 4,823.2
Balance	4,851.2
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(18.2)
Other comprehensive income before reclassifications	6.1
Amount reclassified from accumulated other comprehensive loss	1.2
Other comprehensive income, net	7.3
Balance	(10.9)
Unrealized Gains/Losses on Available-for- Sale Debt Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	25.5
Other comprehensive income before reclassifications	1.8
Amount reclassified from accumulated other comprehensive loss	0
Other comprehensive income, net	1.8
Balance	27.3
Unrealized Gains/Losses on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(0.9)
Other comprehensive income before reclassifications	2.1
Amount reclassified from accumulated other comprehensive loss	1.2
Other comprehensive income, net	3.3
Balance	2.4
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance	(42.8)
Other comprehensive income before reclassifications	2.2
Amount reclassified from accumulated other comprehensive loss	0
Other comprehensive income, net	2.2
Balance	$ (40.6)

Employee Benefit Plans - Equity

Employee Benefit Plans - Equity Incentive Plan (Details) shares in Millions	Mar. 31, 2019shares
Equity incentive plan 2015
Share-Based Compensation Plans
Number of shares available for future issuance	11.4
Employee stock purchase plan 2008
Share-Based Compensation Plans
Number of shares available for future issuance	7.4

Employee Benefit Plans - Restri

Employee Benefit Plans - Restricted Sotck Unit and Performance Share Award Activities (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 29, 2019	Mar. 31, 2019	Mar. 31, 2018
Weighted Average Grant-Date Fair Value per Share
Cash dividends declared per share of common stock (in dollars per share)	$ 0.19	$ 0.19	$ 0.18
RSUs, RSAs, and PSAs
Number of Shares
Balance at beginning of period (in shares)		17.4
Balance at end of period (in shares)		17.7
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)		$ 25.21
Weighted average remaining contractual term		1 year 6 months
Aggregate intrinsic value		$ 467.8
Restricted Stock Units (RSUs)
Number of Shares
Granted (in shares)		5.5
Vested (in shares)		(3.9)
Canceled (in shares)		(0.8)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$ 25.53
Vested (in dollars per share)		26
Canceled (in dollars per share)		$ 26.32
Performance goal, number of shares (in shares)		0.2
Restricted Stock Awards (RSAs)
Number of Shares
Vested (in shares)		(0.1)
Weighted Average Grant-Date Fair Value per Share
Vested (in dollars per share)		$ 23.13
Performance shares (PSAs)
Number of Shares
Granted (in shares)		0.7
Vested (in shares)		(0.5)
Canceled (in shares)		(0.6)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$ 25.06
Vested (in dollars per share)		26.76
Canceled (in dollars per share)		$ 23.25
Performance goal, number of shares (in shares)		0.4
Number of shares modified		0.3
Incremental compensation cost resulting from the modifications		$ 7.7
Minimum | Restricted Stock Units (RSUs)
Weighted Average Grant-Date Fair Value per Share
Performance goal, number of shares (in shares)		0
Minimum | Performance shares (PSAs)
Weighted Average Grant-Date Fair Value per Share
Performance goal, number of shares (in shares)		0
Maximum | Restricted Stock Units (RSUs)
Weighted Average Grant-Date Fair Value per Share
Performance goal, number of shares (in shares)		0.4
Maximum | Performance shares (PSAs)
Weighted Average Grant-Date Fair Value per Share
Performance goal, number of shares (in shares)		0.7

Employee Benefit Plans - Employ

Employee Benefit Plans - Employee Stock Purchase Plan (Details) shares in Millions	Nov. 06, 2017period	Mar. 31, 2019$ / sharesshares	Mar. 31, 2018$ / sharesshares
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
ESPP offering period duration	24 months
ESPP, number of purchase period | period	4
ESPP. purchase period	6 months
ESPP, purchase price of common stock	85.00%
Employee stock purchase plan 2008
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares purchased (in shares) | shares		1.2	1.3
Average exercise price per share (in dollars per share) | $ / shares		$ 22.04	$ 22.23

Employee Benefit Plans - Share

Employee Benefit Plans - Share Based Compensation by Cost and Expense Categories (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 33.9	$ 70.4
Stock options
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	0.1	0.1
RSUs, RSAs, and PSAs
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	29.1	65.6
ESPP
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	4.7	4.7
Cost of revenues - Product
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	1.9	1.9
Cost of revenues - Service
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	4.5	4.8
Research and development
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	12.2	44.1
Sales and marketing
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	9.4	13.5
General and administrative
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 5.9	$ 6.1

Employee Benefit Plans - Shar_2

Employee Benefit Plans - Share Based Compensation by Share Based Payment Award Types (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Unrecognized compensation cost	$ 369.5
Unrecognized compensation, weighted average recognition period	1 year 10 months 25 days

Segments - Revenue by Product (

Segments - Revenue by Product (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)segment	Mar. 31, 2018USD ($)Reportable_Segment
Segment Reporting Information [Line Items]
Number of reportable segments	1	1
Total net revenues	$ 1,001.7	$ 1,082.6
Product
Segment Reporting Information [Line Items]
Total net revenues	618.7	710.8
Routing
Segment Reporting Information [Line Items]
Total net revenues	374.7	408.1
Switching
Segment Reporting Information [Line Items]
Total net revenues	176.4	230
Security
Segment Reporting Information [Line Items]
Total net revenues	67.6	72.7
Service
Segment Reporting Information [Line Items]
Total net revenues	$ 383	$ 371.8

Segments - Revenues by Customer

Segments - Revenues by Customer Vertical (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total net revenues	$ 1,001.7	$ 1,082.6
Cloud
Segment Reporting Information [Line Items]
Total net revenues	223.1	270.9
Service Provider
Segment Reporting Information [Line Items]
Total net revenues	435.6	480.1
Enterprise
Segment Reporting Information [Line Items]
Total net revenues	$ 343	$ 331.6

Segments - Geographic (Details)

Segments - Geographic (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Total net revenues	$ 1,001.7	$ 1,082.6
Total Americas
Segment Reporting Information [Line Items]
Total net revenues	543.6	587.6
United States
Segment Reporting Information [Line Items]
Total net revenues	476.6	532.3
Other
Segment Reporting Information [Line Items]
Total net revenues	67	55.3
Europe, Middle East, and Africa
Segment Reporting Information [Line Items]
Total net revenues	286.2	308
Asia Pacific
Segment Reporting Information [Line Items]
Total net revenues	$ 171.9	$ 187

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income before income taxes	$ 44.5	$ 41.4
Income tax provision	$ 13.4	$ 7
Effective tax rate	30.10%	16.90%
Federal statutory rate	21.00%
Unrecognized tax benefits	$ 181.6
Unrecognized tax benefits, if recognized, would affect the effective tax rate	178.2
Unrecognized tax benefits could decrease up to	$ 30.4

Net Income Per Share (Details)

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net income	$ 31.1	$ 34.4
Denominator:
Weighted-average shares used to compute basic net income per share (in shares)	348.1	355.3
Dilutive effect of employee stock awards (in shares)	4.6	5.3
Weighted-average shares used to compute diluted net income per share (in shares)	352.7	360.6
Net income per share
Basic (in dollars per share)	$ 0.09	$ 0.10
Diluted, (in dollars per share)	$ 0.09	$ 0.10
Anti-dilutive shares (in shares)	5	10.4

Commitments and Contingencies -

Commitments and Contingencies - Leases Additional Information (Details)	Mar. 31, 2019
Minimum | Corporate offices, data centers, and R&D facilities
Lessee, Lease, Description [Line Items]
Lease terms	1 year
Minimum | Vehicles and various office equipment
Lessee, Lease, Description [Line Items]
Lease terms	1 year
Maximum | Corporate offices, data centers, and R&D facilities
Lessee, Lease, Description [Line Items]
Lease terms	7 years
Maximum | Vehicles and various office equipment
Lessee, Lease, Description [Line Items]
Lease terms	3 years

Commitments and Contingencies_2

Commitments and Contingencies - Components of Lease Costs and Other Information Related to Leases (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 11.9
Variable lease cost	3.1
Total lease cost	15
Operating cash outflows from operating leases	11.6
ROU assets obtained in exchange for new operating lease liabilities	$ 0.6
Weighted average remaining lease term (years)	6 years
Weighted average discount rate	4.40%

Commitments and Contingencies_3

Commitments and Contingencies - Future Minimum Operating Lease Payments and Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019
Commitments and Contingencies Disclosure [Abstract]
2019	$ 32.9
2020	47.3
2021	40.4
2022	32.7
2023	29.8
Thereafter	60.3
Total lease payments	243.4
Less: interest	(30)
Total	213.4
Current operating lease liabilities	36.7
Long-term operating lease liabilities	$ 176.7	$ 185.5

Commitments and Contingencies_4

Commitments and Contingencies - Commitments (Details) $ in Millions	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Purchase obligation	$ 632.4
Excess purchase commitments and obsolete materials liability	$ 32.8

Commitments and Contingencies_5

Commitments and Contingencies - Investigations (Details) $ in Millions	Mar. 31, 2019USD ($)
Investigations by U.S. Securities and Exchange Commission (SEC) and U.S. Department of Justice (DOJ) | Pending Litigation
Loss Contingencies [Line Items]
Estimated legal reserve	$ 12

Commitments and Contingencies_6

Commitments and Contingencies - Debt (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Feb. 28, 2019	Mar. 31, 2019	Mar. 31, 2018
Debt Instrument [Line Items]
Payment of debt		$ 350	$ 0
3.125% fixed-rate notes (2019 Notes)
Debt Instrument [Line Items]
Payment of debt	$ 350
Stated interest rate	3.125%

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, shares in Millions	Apr. 29, 2019USD ($)shares	Apr. 25, 2019$ / shares	Apr. 01, 2019USD ($)	Jan. 29, 2019$ / shares	Apr. 30, 2019USD ($)extension_option	Mar. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018shares	Mar. 31, 2018USD ($)$ / sharesshares	Sep. 30, 2018USD ($)	Feb. 28, 2018USD ($)
Dividends
Cash dividends declared per share of common stock (in dollars per share) | $ / shares				$ 0.19		$ 0.19		$ 0.18
Stock Repurchase Activities
Up-front payment pursuant to common stock repurchased and retired						$ 2,900,000		$ 754,200,000
Common stock repurchased and retired, aggregate price						2,900,000		$ 604,200,000
2019 Restructuring Plan
Restructuring
Severance Costs						$ 15,100,000
Accelerated Share Repurchase Program
Stock Repurchase Activities
Stock repurchase program, authorized amount										$ 750,000,000
Up-front payment pursuant to common stock repurchased and retired									$ 750,000,000
Stock repurchased and retired (in shares) | shares						29.3	6	23.3
Subsequent Event
Dividends
Cash dividends declared per share of common stock (in dollars per share) | $ / shares		$ 0.19
Subsequent Event | 2019 Restructuring Plan | Minimum
Restructuring
Severance Costs					$ 6,000,000
Subsequent Event | 2019 Restructuring Plan | Maximum
Restructuring
Severance Costs					7,500,000
Subsequent Event | Accelerated Share Repurchase Program
Stock Repurchase Activities
Stock repurchase program, authorized amount	$ 300,000,000
Up-front payment pursuant to common stock repurchased and retired	$ 300,000,000
Stock repurchased and retired (in shares) | shares	8.6
Common stock repurchased and retired, aggregate price	$ 240,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 1,000,000,000
Subsequent Event | Line of Credit | Unsecured Revolving Credit Facility
Credit Facility
Borrowing capacity					500,000,000
Increase amount of borrowings, subject to lenders' approval					$ 200,000,000
Initial term					5 years
Number of extension options | extension_option					2
Extension option term					1 year
Subsequent Event | Mist
Mist Acquisition
Cash consideration			$ 365,000,000

Uncategorized Items - jnpr-2019

Label	Element	Value
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] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(4,800,000)
Accounting Standards Update 2014-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	313,600,000
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
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	5,700,000
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (5,700,000)