Juniper Networks (JNPR) 10-Q 8 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	May 05, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	JUNIPER NETWORKS INC
Entity Central Index Key	1,043,604
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Amendment Flag	false
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		382,096,479

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net revenues:
Product	$ 828.9	$ 753
Service	392.1	344.9
Total net revenues	1,221	1,097.9
Cost of revenues:
Product	330.2	277.9
Service	144.2	129.1
Total cost of revenues	474.4	407
Gross margin	746.6	690.9
Operating expenses:
Research and development	276.2	251
Sales and marketing	244.2	231.8
General and administrative	50.5	59.4
Restructuring charges	19.4	0
Total operating expenses	590.3	542.2
Operating income	156.3	148.7
Other expense, net	(15.7)	(22.2)
Income before income taxes	140.6	126.5
Income tax provision	31.8	35.1
Net income	$ 108.8	$ 91.4
Net income per share:
Basic, in dollars per share	$ 0.29	$ 0.24
Diluted, in dollars per share	$ 0.28	$ 0.23
Shares used in computing net income per share:
Basic (in shares)	380.9	383.2
Diluted (in shares)	388	389.3
Cash dividends declared per common stock (in dollars per share)	$ 0.10	$ 0.10

Condensed Consolidated Stateme3

Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 108.8	$ 91.4
Available-for-sale securities:
Unrealized gains net of tax provision of $0.7 and benefit of $0.1, respectively	1.5	4.3
Reclassification adjustment for realized net (gains) losses included in net income, net of tax provisions of zero for each period	(0.1)	0.1
Net change on available-for-sale securities, net of taxes	1.4	4.4
Cash flow hedges:
Unrealized gains net of tax provision of $1.7 and $0.5, respectively	5.3	2.5
Reclassification adjustment for realized net losses included in net income, net of tax provision of $0.3 and benefit of $0.2, respectively	1.1	1.1
Net change on cash flow hedges, net of taxes	6.4	3.6
Change in foreign currency translation adjustments	7.9	3.7
Other comprehensive income, net of tax	15.7	11.7
Comprehensive income	$ 124.5	$ 103.1

Condensed Consolidated Stateme4

Condensed Consolidated Statements of Comprehensive Income (Parentheticals) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Tax (provision) benefit on change in unrealized gains on available-for-sale securities	$ (0.7)	$ 0.1
Tax provision on reclassification adjustment for realized net (gains) losses on available-for-sale securities included in net income	0	0
Tax provision on change in unrealized gains on cash flow hedges	(1.7)	(0.5)
Tax provision (benefit) on reclassification adjustment for realized net losses included in net income	$ 0.3	$ (0.2)

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 2,242	$ 1,833.2
Short-term investments	742.3	752.3
Accounts receivable, net of allowances	670.9	1,054.1
Prepaid expenses and other current assets	338.6	332.3
Total current assets	3,993.8	3,971.9
Property and equipment, net	1,050.4	1,063.8
Long-term investments	1,059.4	1,071.8
Restricted cash and investments	93.5	99.9
Purchased intangible assets, net	125.9	130.2
Goodwill	3,079.4	3,081.7
Other long-term assets	235.6	237.2
Total assets	9,638	9,656.5
Current liabilities:
Accounts payable	201.9	221
Accrued compensation	177.4	233.6
Deferred revenue	992.5	1,032
Other accrued liabilities	210.8	249.3
Total current liabilities	1,582.6	1,735.9
Long-term debt	2,134.4	2,133.7
Long-term deferred revenue	500.5	449.1
Long-term income taxes payable	216.7	209.2
Other long-term liabilities	185.4	166.1
Total liabilities	4,619.6	4,694
Commitments and contingencies (Note 15)
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; 382.5 shares and 381.1 shares issued and outstanding as of March 31, 2017 and December 31, 2016, respectively	0	0
Additional paid-in capital	8,288.7	8,281.6
Accumulated other comprehensive loss	(21.6)	(37.3)
Accumulated deficit	(3,248.7)	(3,281.8)
Total stockholders' equity	5,018.4	4,962.5
Total liabilities and stockholders' equity	$ 9,638	$ 9,656.5

Condensed Consolidated Balance6

Condensed Consolidated Balance Sheets (Parentheticals) (Unaudited) - $ / shares	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Convertible preferred stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Convertible preferred stock - shares authorized	10,000,000	10,000,000
Convertible preferred stock - issued	0	0
Convertible preferred stock - outstanding	0	0
Common stock - par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock - shares authorized	1,000,000,000	1,000,000,000
Common stock - issued	382,500,000	381,100,000
Common stock - outstanding	382,500,000	381,100,000

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 108.8	$ 91.4
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	62	51.8
Depreciation, amortization, and accretion	55.8	47
Deferred income taxes	15.3	21.1
(Gain) loss on investments and fixed assets, net	(1)	5.4
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	383	(3.2)
Prepaid expenses and other assets	(3.5)	(59.6)
Accounts payable	(18.4)	69.8
Accrued compensation	(47.2)	(89.3)
Income taxes payable	4.1	(24.2)
Other accrued liabilities	(25.5)	(29.8)
Deferred revenue	11.9	92
Net cash provided by operating activities	545.3	172.4
Cash flows from investing activities:
Purchases of property and equipment	(32.1)	(49.3)
Purchases of available-for-sale investments	(378.9)	(360.7)
Proceeds from sales of available-for-sale investments	218.8	286.2
Proceeds from maturities and redemptions of available-for-sale investments	184.3	79.6
Purchases of trading investments	(1.8)	(2.5)
Purchases of privately-held investments	0	(10.5)
Net cash used in investing activities	(9.7)	(57.2)
Cash flows from financing activities:
Proceeds from issuance of common stock	33.7	32
Purchases and retirement of common stock	(129.7)	(83.4)
Issuance of debt, net	0	494
Payment of debt	0	(300)
Payment of cash dividends	(38)	(38.3)
Net cash (used in) provided by financing activities	(134)	104.3
Effect of foreign currency exchange rates on cash and cash equivalents	7.2	5.6
Net increase in cash and cash equivalents	408.8	225.1
Cash and cash equivalents at beginning of period	1,833.2	1,420.9
Cash and cash equivalents at end of period	$ 2,242	$ 1,646

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
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 United States of America (“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, 2016 , 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, 2017 , are not necessarily indicative of the results that may be expected for the year ending December 31, 2017 , 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, 2016 (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, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Except for the change in certain policies related to share-based compensation upon adoption of the accounting standard 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 Standard On January 1 2017, the Company adopted Financial Accounting Standards Board ("FASB") ASU No. 2016-09 (Topic 718) Compensation—Stock Compensation: Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"), which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, forfeiture, statutory tax withholding requirements, and classification on the statement of cash flows. The impact of the adoption on the Company's condensed consolidated financial statements was as follows: • Forfeitures: The Company elected to account for forfeitures as they occur using a modified retrospective transition method, rather than estimating forfeitures, resulting in a cumulative-effect adjustment of $9.0 million , which increased the January 1, 2017 opening accumulated deficit balance on the Condensed Consolidated Balance Sheets. • Income tax accounting: The Company is also required to record excess tax benefits and tax deficiencies related to stock- based compensation as income tax benefit or expense in the statement of operations prospectively when share-based awards vest or are settled. Upon adoption, the Company recognized the previously unrecognized excess tax benefits using the modified retrospective transition method, which resulted in no impact to the January 1, 2017 opening accumulated deficit balance as previously unrecognized excess tax effects were fully offset by a valuation allowance. • Cash flow presentation of excess tax benefits: The Company is required to classify excess tax benefits along with other income tax cash flows as an operating activity either prospectively or retrospectively. The Company elected to apply the change in presentation to the statements of cash flows retrospectively and no longer classify the excess tax benefits from share-based compensation as a financing activity. There were no excess tax benefits reported in the Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016. Recent Accounting Standards Not Yet Effective In March 2017, the FASB issued 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 ASU will not impact debt securities held at a discount. This standard is effective for annual reporting periods beginning after December 15, 2018, including interim reporting periods within those annual reporting periods, and is to be applied on a modified retrospective basis with early adoption permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In February 2017, the FASB issued ASU No. 2017-05 Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets which amends guidance on how entities account for the derecognition of a nonfinancial asset or an in substance nonfinancial asset that is not a business. This standard is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods, and is to be applied on either a retrospective or modified retrospective basis with early adoption permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. 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 guidance 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. In January 2017, the FASB issued ASU No. 2017-01 (Topic 805) Business Combinations: Clarifying the Definition of a Business , which clarifies the definition of a business and assists entities with evaluating when a set of transferred assets and activities is a business. This ASU is effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted. In November 2016, the FASB issued ASU No. 2016-18 (Topic 230) Statement of Cash Flow: Restricted Cash, which provides guidance on the classification of restricted cash to be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of this ASU are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. The standard must be applied retrospectively to all periods presented. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In October 2016, the FASB issued ASU No. 2016-16 (Topic 740) Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory, which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. ASU 2016-16 will be effective for annual and interim reporting periods beginning after December 15, 2017 and is to be applied on a modified retrospective basis. Early adoption is permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In August 2016, the FASB issued ASU No. 2016-15 (Topic 230) Statement of Cash Flow: Classification of Certain Cash Receipts and Cash Payments, which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. This pronouncement is effective for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact that this standard will have on its Consolidated Statements of Cash Flows. 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. This pronouncement is 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 that this standard will have on its Consolidated Financial Statements and disclosures. In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases ("ASU 2016-02"), which requires recognition of lease assets and lease liabilities on the balance sheet by lessees for leases classified as operating leases with a lease term of more than twelve months. ASU 2016-02 should be applied on a modified retrospective basis and is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adoption of this standard, however it is expected to have a material impact on the Company's Consolidated Financial Statements and disclosures. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall: Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), which changes how entities measure equity investments and present changes in the fair value of financial liabilities measured under the fair value option. The guidance also updates certain presentation and disclosure requirements. ASU 2016-01 is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact that ASU 2016-01will have on its Consolidated Financial Statements and disclosures. In May 2014, the FASB issued ASU No. 2014-09 (Topic 606) —Revenue from Contracts with Customers and several amendments thereafter (“ASU 2014-09”), which provides guidance for revenue recognition that will supersede the revenue recognition requirements in Topic 605, and most industry specific guidance. The core principle for ASU 2014-09 is that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017. The Company intends to adopt ASU 2014-09 on January 1, 2018 retrospectively, applying the amendments to each prior reporting period presented and remains on schedule with its implementation and the preparation of its prior-period financial statements . Upon adoption, the Company expects a material impact to the opening balance sheet as of January 1, 2016 related to the cumulative effect of adopting the standard, primarily due to the application of the new guidance in the areas of distributor sales, software revenue, contract acquisition costs, variable consideration, and revenue allocation. The Company will continue to assess the impact of ASU 2014-09 including any changes to systems, processes and the control environment as it works through the adoption in 2017, and there remain areas still to be fully concluded upon. In addition, there are ongoing interpretive reviews, which may alter the Company's conclusions and the financial impact of ASU 2014-09. For further information, refer to Note 2, Significant Accounting Policies , in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K.

Cash Equivalents and Investment

Cash Equivalents and Investments	3 Months Ended
	Mar. 31, 2017
Cash Equivalents and Investments [Abstract]
Cash Equivalents and Investments	Cash Equivalents and Investments Investments in Available-for-Sale and Trading Securities The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of March 31, 2017 and December 31, 2016 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of March 31, 2017 Fixed income securities: Asset-backed securities $ 314.6 $ — $ (0.4 ) $ 314.2 Certificates of deposit 57.4 — — 57.4 Commercial paper 125.9 — — 125.9 Corporate debt securities 856.1 0.8 (1.5 ) 855.4 Foreign government debt securities 40.0 — (0.1 ) 39.9 Time deposits 245.8 — — 245.8 U.S. government agency securities 132.4 — (0.4 ) 132.0 U.S. government securities 380.7 0.1 (0.4 ) 380.4 Total fixed income securities 2,152.9 0.9 (2.8 ) 2,151.0 Money market funds 1,117.3 — — 1,117.3 Mutual Funds 8.3 — — 8.3 Publicly-traded equity securities 4.6 1.6 — 6.2 Total available-for-sale securities 3,283.1 2.5 (2.8 ) 3,282.8 Trading securities in mutual funds 22.6 — — 22.6 Total $ 3,305.7 $ 2.5 $ (2.8 ) $ 3,305.4 Reported as: Cash equivalents $ 1,429.9 $ — $ — $ 1,429.9 Restricted investments 73.8 — — 73.8 Short-term investments 741.0 1.8 (0.5 ) 742.3 Long-term investments 1,061.0 0.7 (2.3 ) 1,059.4 Total $ 3,305.7 $ 2.5 $ (2.8 ) $ 3,305.4 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2016 Fixed income securities: Asset-backed securities $ 303.0 $ 0.2 $ (0.2 ) $ 303.0 Certificates of deposit 66.1 — — 66.1 Commercial paper 147.7 — — 147.7 Corporate debt securities 846.5 0.4 (2.0 ) 844.9 Foreign government debt securities 34.0 — (0.1 ) 33.9 Time deposits 264.6 — — 264.6 U.S. government agency securities 127.0 — (0.3 ) 126.7 U.S. government securities 390.7 0.1 (0.4 ) 390.4 Total fixed income securities 2,179.6 0.7 (3.0 ) 2,177.3 Money market funds 592.2 — — 592.2 Mutual funds 8.0 — — 8.0 Publicly-traded equity securities 5.3 — (0.7 ) 4.6 Total available-for-sale securities 2,785.1 0.7 (3.7 ) 2,782.1 Trading securities in mutual funds 21.0 — — 21.0 Total $ 2,806.1 $ 0.7 $ (3.7 ) $ 2,803.1 Reported as: Cash equivalents $ 907.1 $ — $ — $ 907.1 Restricted investments 71.9 — — 71.9 Short-term investments 753.4 0.1 (1.2 ) 752.3 Long-term investments 1,073.7 0.6 (2.5 ) 1,071.8 Total $ 2,806.1 $ 0.7 $ (3.7 ) $ 2,803.1 The following table presents the contractual maturities of the Company's total fixed income securities as of March 31, 2017 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,092.0 $ 1,091.7 Due between one and five years 1,060.9 1,059.3 Total $ 2,152.9 $ 2,151.0 The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of March 31, 2017 and December 31, 2016 (in millions): Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss As of March 31, 2017 Fixed income securities: Asset-backed securities $ 260.9 $ (0.4 ) $ — $ — $ 260.9 $ (0.4 ) Corporate debt securities 432.8 (1.4 ) 50.9 (0.1 ) 483.7 (1.5 ) Foreign government debt securities 23.3 (0.1 ) — — 23.3 (0.1 ) U.S. government agency securities 106.1 (0.4 ) — — 106.1 (0.4 ) U.S. government securities 272.8 (0.4 ) — — 272.8 (0.4 ) Total fixed income securities 1,095.9 (2.7 ) 50.9 (0.1 ) 1,146.8 (2.8 ) Total available-for-sale securities $ 1,095.9 $ (2.7 ) $ 50.9 $ (0.1 ) $ 1,146.8 $ (2.8 ) Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss As of December 31, 2016 Fixed income securities: Asset-backed securities $ 122.2 $ (0.2 ) $ — $ — $ 122.2 $ (0.2 ) Corporate debt securities 470.8 (1.9 ) 76.7 (0.1 ) 547.5 (2.0 ) Foreign government debt securities 20.3 (0.1 ) — — 20.3 (0.1 ) U.S. government agency securities 106.7 (0.3 ) — — 106.7 (0.3 ) U.S. government securities 254.1 (0.4 ) — — 254.1 (0.4 ) Total fixed income securities 974.1 (2.9 ) 76.7 (0.1 ) 1,050.8 (3.0 ) Publicly-traded equity securities 4.6 (0.7 ) — — 4.6 (0.7 ) Total available-for-sale securities $ 978.7 $ (3.6 ) $ 76.7 $ (0.1 ) $ 1,055.4 $ (3.7 ) The Company had 544 and 494 investments in unrealized loss positions as of March 31, 2017 and December 31, 2016 , respectively. The gross unrealized losses related to these investments were primarily due to changes in market interest rates and stock prices. The Company periodically reviews its investments to identify and evaluate investments that have an indication of possible impairment. The Company aggregates its investments by category and length of time the securities have been in a continuous unrealized loss position to facilitate its evaluation. For available-for-sale debt securities that have unrealized losses, the Company evaluates 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, 2017 , 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, 2017 and March 31, 2016 . For available-for-sale equity securities that have unrealized losses, the Company evaluates whether there is an indication of other-than-temporary impairments. This determination is based on several factors, including the financial condition and near-term prospects of the issuer and the Company's intent and ability to hold the publicly-traded equity securities for a period of time sufficient to allow for any anticipated recovery in market value. During the three months ended March 31, 2017 and March 31, 2016 , there were no other-than-temporary impairments associated with these investments. During the three months ended March 31, 2017 and March 31, 2016 , there were no material gross realized gains or losses from either available-for-sale securities or from trading securities. Restricted Cash and Investments There have been no material changes to the composition of the Company's restricted cash and investments as described in Note 4, Cash Equivalents and Investments , in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K. The restricted investments are designated as available-for-sale securities except relating to the non-qualified deferred compensation plan which are designated as trading securities. As of March 31, 2017 , total restricted cash and investments was $114.0 million , of which $20.5 million was included in prepaid expenses and other current assets and $93.5 million was included in restricted cash and investments, respectively, on the Condensed Consolidated Balance Sheets. Investments in Privately-Held Companies As of March 31, 2017 and December 31, 2016 , the carrying values of the Company's investments in privately-held companies of $62.7 million for both periods, were included in other long-term assets in the Condensed Consolidated Balance Sheets. These investments include debt and redeemable preferred stock securities that are carried at fair value, and non-redeemable preferred stock securities that are carried at cost. As of March 31, 2017 and December 31, 2016 , the carrying value of the investments accounted for under the cost method were $20.4 million and $19.0 million , respectively. See Note 4, Fair Value Measurements , for the Company's investments in privately-held companies that are carried at fair value. The Company adjusts the carrying value for its investments in privately-held companies that are carried at cost for any impairment if the fair value is less than the carrying value of the respective assets on an other-than-temporary basis. During the three months ended March 31, 2016 , the Company determined that certain investments in privately-held companies were other than-temporarily impaired, resulting in impairment charges of $5.1 million , that was recorded within other expense, net in the Condensed Consolidated Statement of Operations. There were no impairment charges for the three months ended March 31, 2017 .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 Using: Quoted Prices in Active Markets For Identical Assets Significant Other Observable Remaining Inputs Significant Other Unobservable Remaining Inputs (Level 1) (Level 2) (Level 3) Total Assets measured at fair value: Available-for-sale securities: Asset-backed securities $ — $ 314.2 $ — $ 314.2 Certificates of deposit — 57.4 — 57.4 Commercial paper — 125.9 — 125.9 Corporate debt securities — 855.4 — 855.4 Foreign government debt securities — 39.9 — 39.9 Money market funds 1,117.3 — — 1,117.3 Mutual funds 8.3 — — 8.3 Publicly-traded equity securities 6.2 — — 6.2 Time Deposits — 245.8 — 245.8 U.S. government agency securities — 132.0 — 132.0 U.S. government securities 337.3 43.1 — 380.4 Total available-for-sale securities 1,469.1 1,813.7 — 3,282.8 Trading securities in mutual funds 22.6 — — 22.6 Privately-held debt and redeemable preferred stock securities — — 42.3 42.3 Derivative assets: Foreign exchange contracts — 4.5 — 4.5 Total assets measured at fair value $ 1,491.7 $ 1,818.2 $ 42.3 $ 3,352.2 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (1.2 ) $ — $ (1.2 ) Total liabilities measured at fair value $ — $ (1.2 ) $ — $ (1.2 ) Total assets measured at fair value, reported as: Cash equivalents $ 1,074.4 $ 355.5 $ — $ 1,429.9 Restricted investments 73.8 — — 73.8 Short-term investments 186.8 555.5 — 742.3 Long-term investments 156.7 902.7 — 1,059.4 Prepaid expenses and other current assets — 4.5 — 4.5 Other long-term assets — — 42.3 42.3 Total assets measured at fair value $ 1,491.7 $ 1,818.2 $ 42.3 $ 3,352.2 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (1.2 ) $ — $ (1.2 ) Total liabilities measured at fair value $ — $ (1.2 ) $ — $ (1.2 ) Fair Value Measurements at December 31, 2016 Using: Quoted Prices in Active Markets For Identical Assets Significant Other Observable Remaining Inputs Significant Other Unobservable Remaining Inputs (Level 1) (Level 2) (Level 3) Total Assets measured at fair value: Available-for-sale securities: Asset-backed securities $ — $ 303.0 $ — $ 303.0 Certificates of deposit — 66.1 — 66.1 Commercial paper — 147.7 — 147.7 Corporate debt securities — 844.9 — 844.9 Foreign government debt securities — 33.9 — 33.9 Money market funds 592.2 — — 592.2 Mutual funds 8.0 — — 8.0 Publicly-traded equity securities 4.6 — — 4.6 Time Deposits — 264.6 — 264.6 U.S. government agency securities — 126.7 — 126.7 U.S. government securities 345.0 45.4 — 390.4 Total available-for-sale securities 949.8 1,832.3 — 2,782.1 Trading securities in mutual funds 21.0 — — 21.0 Privately-held debt and redeemable preferred stock securities — — 43.7 43.7 Derivative assets: Foreign exchange contracts — 0.9 — 0.9 Total assets measured at fair value $ 970.8 $ 1,833.2 $ 43.7 $ 2,847.7 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (4.9 ) $ — $ (4.9 ) Total liabilities measured at fair value $ — $ (4.9 ) $ — $ (4.9 ) Total assets measured at fair value, reported as: Cash equivalents $ 549.3 $ 357.7 $ — $ 907.0 Restricted investments 71.9 — — 71.9 Short-term investments 178.1 574.3 — 752.4 Long-term investments 171.5 900.3 — 1,071.8 Prepaid expenses and other current assets — 0.9 — 0.9 Other long-term assets — — 43.7 43.7 Total assets measured at fair value $ 970.8 $ 1,833.2 $ 43.7 $ 2,847.7 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (4.9 ) $ — $ (4.9 ) Total liabilities measured at fair value $ — $ (4.9 ) $ — $ (4.9 ) The Company's Level 2 available-for-sale fixed income 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, 2017 , 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, 2017 , there were no purchases or sales or gains or losses related to privately-held debt and redeemable preferred stocks securities. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis As of March 31, 2017 , the Company had no assets measured at fair value on a nonrecurring basis. Investments in privately-held companies, which are normally carried at cost, are measured at fair value on a nonrecurring basis due to events and circumstances that the Company identifies as significantly impacting the carrying value of the investments. As of December 31, 2016 , certain investments in privately-held companies with a carrying value of $1.6 million were impaired and written-down to their fair value of zero and were classified as Level 3 assets due to lack of observable inputs to determine fair value. The Company estimates the fair value of its investments in privately-held companies using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. The impairment charge was recorded to other expense, net in the Condensed Consolidated Statements of Operations. As of March 31, 2017 and December 31, 2016 , the Company had no liabilities measured at fair value on a nonrecurring basis. Assets and Liabilities Not Measured at Fair Value The carrying amounts of the Company's accounts receivable, financing receivables, accounts payable, and other accrued liabilities approximate fair value due to their short maturities. As of March 31, 2017 and December 31, 2016 , the estimated fair value of the Company's long-term debt in the Condensed Consolidated Balance Sheets was approximately $2,253.3 million and $2,215.7 million , respectively, based on observable market inputs (Level 2). The carrying value of the promissory note issued to the Company in connection with the previously-completed sale of Junos Pulse (the “Pulse Note”), of $132.9 million approximates its fair value, of which $75.0 million is recorded in prepaid expenses and other current assets and the remaining balance is recorded within other long-term assets in the Condensed Consolidated Balance Sheets as of March 31, 2017 and December 31, 2016 . The Pulse Note is classified as a Level 3 asset due to the lack of observable inputs to determine fair value. See Note 7, Other Financial Information , for further information on the Pulse Note.

Derivative Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2017
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 Company uses foreign currency forwards to hedge the Company's planned cost of services and operating expenses denominated in foreign currencies. The notional amount of the Company's foreign currency derivatives that are designated as cash flow hedges are summarized as follows (in millions): As of March 31, December 31, Cash flow hedges $ 222.8 $ 172.0 Execution of these cash flow hedge derivatives typically occurs every month with maturities of eighteen months or less. As of March 31, 2017, the estimated net amount of the existing gains or losses expected to be reclassified into earnings within the next 12 months was not material. The Company recognized a gain of $7.0 million and $3.0 million in accumulated other comprehensive loss for the effective portion of its derivative instruments as of March 31, 2017 and March 31, 2016 , respectively. The amount reclassified out of accumulated other comprehensive loss to cost of revenues and operating expense in the Condensed Consolidated Statements of Operations was insignificant during the three months ended March 31, 2017 and March 31, 2016 . The ineffective portion of the Company's derivative instruments recognized in its Condensed Consolidated Statements of Operations was not material during the three months ended March 31, 2017 and March 31, 2016 . See Note 4, Fair Value Measurements , for the fair values of the Company's derivative instruments in the Condensed Consolidated Balance Sheets.

Goodwill and Purchased Intangib

Goodwill and Purchased Intangible Assets	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Purchased Intangible Assets	Goodwill and Purchased Intangible Assets Goodwill The following table presents goodwill activity (in millions): Balance as of December 31, 2016 $ 3,081.7 Other (*) (2.3 ) Balance as of March 31, 2017 $ 3,079.4 ________________________________ (*) Other primarily consists of certain purchase accounting adjustments related to previously completed business combinations. Purchased Intangible Assets The Company’s purchased intangible assets as of March 31, 2017 and December 31, 2016, were $125.9 million and $130.2 million , respectively. Amortization expense during the three months ended March 31, 2017 and March 31, 2016 was $4.3 million and $3.3 million , respectively.

Other Financial Information

Other Financial Information	3 Months Ended
	Mar. 31, 2017
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 $ 78.4 $ 75.6 Finished goods 20.0 19.9 Inventory $ 98.4 $ 95.5 Reported as: Prepaid expenses and other current assets $ 94.8 $ 91.4 Other long-term assets 3.6 4.1 Total $ 98.4 $ 95.5 Note Receivable On October 1, 2014, the Company completed the sale of its Junos Pulse product portfolio. The Company received total consideration of $230.7 million , of which $105.7 million was in cash, net of a $19.3 million working capital adjustment, and $125.0 million was in the form of a non-contingent interest-bearing promissory note due to the Company on April 1, 2016. On October 2, 2015, the Company and the issuer of the Pulse Note mutually agreed to amend the original terms of the Pulse Note to, among other things, extend the maturity date from April 1, 2016 to December 31, 2018, provide that interest due on the Pulse Note through December 31, 2015 shall be paid in kind by increasing the outstanding principal amount of the note and increase the interest rate on the Pulse Note. In addition, under the amended terms of the Pulse Note, the issuer is required to make a minimum payment of $75.0 million on or prior to April 1, 2017, less any principal amount previously pre-paid to the Company. The $75.0 million portion of the note receivable is classified within prepaid expenses and other current assets in the Condensed Consolidated Balance Sheets. The remaining balance, along with interest paid in kind, is classified as a long-term asset based on expected collection beyond twelve months from the Condensed Consolidated Balance Sheet date. The Company considers notes receivable to be impaired when, based on current information and events, it is probable that the Company will not be able to collect the scheduled payments of principal or interest when due. Further, the Company measures any impairment to the Pulse Note based on the present value of expected cash flows, which are discounted at the note's effective interest rate, compared to the recorded investment of the note, including principal and accrued interest. Based on the impairment assessment, no impairment charge was required to the Pulse Note as of March 31, 2017 . Interest income on the Pulse Note is accrued and credited to interest income as it is earned, unless it is not probable the Company will collect the amounts due or if the present value of expected cash flows is less than the recorded investment. During the three months ended March 31, 2017 and March 31, 2016 , the related amount of interest income recognized was $2.7 million for both periods. In May 2017, the Company received payment of $75.0 million and the outstanding interest due and further agreed to amend the terms of the Pulse Note. The new arrangement, among other things, extends the maturity date of the remaining outstanding amount of approximately $58.0 million from December 31, 2018 to September 30, 2022, provides that interest due after April 1, 2017 can be paid-in-kind by increasing the outstanding principal amount of the note or paid in cash, requires the promissory note to be subordinated to other debt raised by the issuer and entitles the Company to additional financial considerations if the issuer of the note and its affiliates meet certain conditions. Warranties Changes during the three months ended March 31, 2017 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, 2016 $ 41.3 Provisions made during the period 12.3 Actual costs incurred during the period (8.1 ) Balance as of March 31, 2017 $ 45.5 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 $ 264.9 $ 302.4 Distributor inventory and other sell-through items 68.7 74.2 Deferred gross product revenue 333.6 376.6 Deferred cost of product revenue (52.3 ) (53.7 ) Deferred product revenue, net 281.3 322.9 Deferred service revenue 1,211.7 1,158.2 Total $ 1,493.0 $ 1,481.1 Reported as: Current $ 992.5 $ 1,032.0 Long-term 500.5 449.1 Total $ 1,493.0 $ 1,481.1 Other Expense, Net Other expense, net, consisted of the following (in millions): Three Months Ended March 31, 2017 2016 Interest income $ 10.4 $ 7.9 Interest expense (25.3 ) (22.5 ) Gain (loss) on investments, net 1.2 (5.4 ) Other (2.0 ) (2.2 ) Other expense, net $ (15.7 ) $ (22.2 )

Restructuring Charges

Restructuring Charges	3 Months Ended
	Mar. 31, 2017
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges In February 2017, the Company initiated a restructuring plan (the “2017 Restructuring Plan”) to realign the Company's workforce and increase operational efficiencies. The 2017 Restructuring Plan costs include workforce reductions and contract terminations. During the three months ended March 31, 2017 , the Company recorded $18.8 million of severance costs and $0.6 million of contract terminations that were recorded to restructuring charges in the Condensed Consolidated Statement of Operations. These costs are expected to be substantially paid during the next six months. The Company does not expect to incur significant future charges under the 2017 Restructuring Plan. Restructuring liabilities are reported within other accrued liabilities on the Condensed Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liabilities primarily related to the 2017 Restructuring Plan initiated during the three months ended March 31, 2017 (in millions): December 31, 2016 (*) Charges Cash Payments Other March 31, Severance $ 0.7 $ 18.8 $ (5.2 ) $ 0.6 $ 14.9 Contract terminations and other 0.5 0.6 — — 1.1 Total $ 1.2 $ 19.4 $ (5.2 ) $ 0.6 $ 16.0 ________________________________ (*) Consists of costs in connection with a prior restructuring plan that is substantially complete.

Debt and Financing

Debt and Financing	3 Months Ended
	Mar. 31, 2017
Debt Instruments [Abstract]
Debt and Financing	Debt and Financing Debt The Company's long-term debt is summarized as follows (in millions, except percentages): As of March 31, 2017 Amount Effective Interest Rates Senior Notes ("Notes"): 3.125% fixed-rate notes, due February 2019 $ 350.0 3.36 % 3.300% fixed-rate notes, due June 2020 300.0 3.47 % 4.600% fixed-rate notes, due March 2021 300.0 4.69 % 4.500% fixed-rate notes, due March 2024, issued March 2014 350.0 4.63 % 4.500% fixed-rate notes, due March 2024, issued February 2016 150.0 4.87 % 4.350% fixed-rate notes, due June 2025 300.0 4.47 % 5.950% fixed-rate notes, due March 2041 400.0 6.03 % Total senior notes 2,150.0 Unaccreted discount and debt issuance costs (15.6 ) Total $ 2,134.4 The Notes above are the Company’s senior unsecured and unsubordinated obligations, ranking equally in right of payment to all of the Company’s existing and future senior unsecured and unsubordinated indebtedness and senior in right of payment to any of the Company’s future indebtedness that is expressly subordinated to the Notes. Interest on the Notes is payable in cash semiannually. The Company may redeem, either in whole or in part, the Senior Notes due 2020 at any time on or after May 15, 2020, the Senior Notes due 2025 at any time on or after March 15, 2025, and the other Notes at any time, in each case, according to the terms of the indentures governing the Notes. In the event of a change of control repurchase event, the holders of the Notes may require the Company to repurchase for cash all or part of the Notes at a purchase price equal to 101% of the aggregate principal amount, plus accrued and unpaid interest, if any. The indentures that govern the Notes also contain various covenants, including limitations on the Company's ability to incur liens or enter into sale-leaseback transactions over certain dollar thresholds. As of March 31, 2017 , the Company was in compliance with all covenants in the indentures governing the Notes. Revolving Credit Facility On June 27, 2014, the Company entered into a Credit Agreement (“Credit Agreement”) with certain institutional lenders that provides for a $500.0 million unsecured revolving credit facility, with an option to increase the amount of the credit facility by up to an additional $200.0 million , subject to certain conditions. Revolving loans may be borrowed, repaid and reborrowed until June 27, 2019, at which time all amounts borrowed must be repaid. Borrowings under the Credit Agreement will bear interest at either i) a floating rate per annum equal to the base rate plus a margin of between 0.00% and 0.50% , depending on the Company's public debt rating or ii) a per annum rate equal to the reserve adjusted Eurocurrency rate , plus a margin of between 0.90% and 1.50% , depending on the Company's public debt rating. As of March 31, 2017 , the Company was in compliance with all covenants in the Credit Agreement, and no amounts were outstanding. Financing Arrangements The Company provides certain channel partners access to extended financing arrangements that require longer payment terms than those typically provided by the Company by factoring accounts receivable to third-party financing providers (“financing providers”). The program does not and is not intended to affect the timing of the Company's revenue recognition. Under the financing arrangements, proceeds from the financing provider are due to the Company within 30 to 90 days from the sale of the receivable. In these transactions with the financing provider, the Company surrenders control over the transferred assets. Pursuant to the financing arrangements for the sale of receivables, the Company sold net receivables of $25.4 million and received cash proceeds from financing providers of $23.1 million during the three months ended March 31, 2017 . As of March 31, 2017 and December 31, 2016 , the amounts owed by the financing provider were $15.9 million and $13.6 million , respectively, which were recorded in accounts receivable on the Condensed Consolidated Balance Sheets.

Equity

Equity	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Equity	Equity Cash Dividends on Shares of Common Stock During the three months ended March 31, 2017 , the Company declared a quarterly cash dividend of $0.10 per share of common stock on January 26, 2017, which was paid on March 22, 2017 to stockholders of record on March 1, 2017 in the aggregate amount of $38.0 million . Any future dividends, and the establishment of record and payment dates, are subject to approval by the Board of Directors (the “Board”) of Juniper Networks or authorized committee thereof. See Note 16, Subsequent Events, for discussion of the Company's dividend declaration subsequent to March 31, 2017 . Stock Repurchase Activities In 2014 and 2015, the Board approved a stock repurchase program that authorized the Company to repurchase up to $2.1 billion of its common stock, including $1.2 billion pursuant to an accelerated share repurchase program, and subsequent increases to the authorization totaling $1.8 billion (“Stock Repurchase Program”). In February 2017, the Board authorized an additional $500.0 million increase to the Stock Repurchase Program for a total of $4.4 billion . The following table summarizes the Company's repurchases and retirements of its common stock under its Stock Repurchase Program (in millions, except per share amounts): Three Months Ended March 31, 2017 2016 Shares repurchased 4.5 3.1 Average price per share $ 28.03 $ 23.89 Amount repurchased $ 125.0 $ 75.0 As of March 31, 2017 , there was $594.7 million of authorized funds remaining under the Stock Repurchase Program. In addition to repurchases under the Stock Repurchase Program, the Company also repurchases common stock from certain employees in connection with the net issuance of shares to satisfy minimum tax withholding obligations upon the vesting of certain stock awards issued to such employees. Repurchases associated with tax withholdings were not significant during the three months ended March 31, 2017 and March 31, 2016 . Future share repurchases under the 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 Stock Repurchase Program may be discontinued at any time. See Note 16, Subsequent Events, for discussion of the Company's stock repurchase activity subsequent to March 31, 2017 . 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, 2017 were as follows (in millions): Unrealized Gains on Available-for- Sale Securities (1) Unrealized (Losses) Gains on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2016 $ 16.6 $ (4.5 ) $ (49.4 ) $ (37.3 ) Other comprehensive gains before reclassifications 1.5 5.3 7.9 14.7 Amount reclassified from accumulated other comprehensive loss (0.1 ) 1.1 — 1.0 Other comprehensive gains, net 1.4 6.4 7.9 15.7 Balance as of March 31, 2017 $ 18.0 $ 1.9 $ (41.5 ) $ (21.6 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive loss during the three months ended March 31, 2017 for realized gains on available-for-sale securities were insignificant, and were included in other expense, net, in the Condensed Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive loss during the three months ended March 31, 2017 for realized gains on cash flow hedges were insignificant, and were included within cost of revenues, research and development, sales and marketing, and general and administrative in the Condensed Consolidated Statements of Operations.

Employee Benefit Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2017
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 has an Employee Stock Purchase Plan (the “ESPP”) for all eligible employees. As of March 31, 2017, 11.6 million and 3.4 million shares were available for future issuance under the Company's stock-based compensation plans and ESPP, respectively. Stock Option Activities The following table summarizes the Company’s stock option activity and related information as of and for the three months ended March 31, 2017 (in millions, except for per share amounts and years): Outstanding Options Number of Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance as of December 31, 2016 2.4 $ 29.20 Exercised (0.2 ) 21.39 Expired/canceled (0.6 ) 30.63 Balance as of March 31, 2017 1.6 $ 29.83 1.8 $ 8.0 As of March 31, 2017: Vested and expected-to-vest options 1.6 $ 29.83 1.8 $ 8.0 Exercisable options 1.5 $ 30.82 1.5 $ 6.6 Restricted Stock Unit, Restricted Stock Award, and Performance Share Award Activities The Company’s RSU, restricted stock award ("RSA"), and PSA activity and related information as of and for the three months ended March 31, 2017 were as follows (in millions, except per share amounts and years): Outstanding RSUs, RSAs, and PSAs Number of Shares Weighted Average Grant-Date Fair Value per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance as of December 31, 2016 20.9 $ 24.05 RSUs granted (1)(3) 5.6 27.52 PSAs granted (2)(3) 0.6 27.32 RSUs vested (3.8 ) 24.14 RSAs vested (0.3 ) 22.69 PSAs vested (0.6 ) 24.41 RSUs canceled (0.4 ) 22.75 PSAs canceled (0.3 ) 24.33 Balance as of March 31, 2017 21.7 $ 24.90 1.4 $ 604.5 ________________________________ (1) Includes service-based and market-based RSUs. (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 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 0 to 0.6 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, 2017 , the Company declared a quarterly cash dividend of $0.10 per share of common stock on January 26, 2017 which was paid on March 22, 2017 to stockholders of record on March 1, 2017, in the aggregate amount of $38.0 million . Employee Stock Purchase Plan The ESPP is implemented in a series of offering periods, each currently six months in duration, or such other period as determined by the Board. Employees purchased approximately 1.5 million and 1.3 million shares of common stock through the ESPP at an average exercise price of $19.21 and $20.06 per share for the three months ended March 31, 2017 and March 31, 2016 , respectively. Share-Based Compensation Expense Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions): Three Months Ended March 31, 2017 2016 Cost of revenues - Product $ 0.9 $ 1.9 Cost of revenues - Service 4.3 3.5 Research and development 34.8 32.3 Sales and marketing 15.3 9.4 General and administrative 6.7 4.7 Total $ 62.0 $ 51.8 The following table summarizes share-based compensation expense by award type (in millions): Three Months Ended March 31, 2017 2016 Stock options $ 0.1 $ 1.2 RSUs, RSAs, and PSAs 57.8 46.8 ESPP 4.1 3.8 Total $ 62.0 $ 51.8 The unrecognized compensation cost recognized over a weighted-average period related to unvested stock options, RSUs, RSAs, and PSAs as of March 31, 2017 were as follows (in millions, except years): Unrecognized Compensation Cost Weighted Average Period (In Years) Stock options $ 1.0 2.1 RSUs, RSAs, and PSAs $ 424.7 1.8

Segments

Segments	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Segments	Segments The Company operates in one reportable segment. Our 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, 2017 2016 Routing $ 521.6 $ 504.1 Switching 241.6 175.5 Security 65.7 73.4 Total product 828.9 753.0 Total service 392.1 344.9 Total $ 1,221.0 $ 1,097.9 In the first quarter of 2017, the Company began reporting revenue on the following key customer verticals: Cloud, Telecom/Cable, and Strategic Enterprise. A summary of the types of customers included in these verticals is as follows: • Cloud: companies that are heavily reliant on the cloud for their business model’s success. As an example, customers in the cloud vertical can include cloud service providers as well as enterprises that provide software-as-a-service, infrastructure-as-a-service, or platform-as-a-service. • Telecom/Cable: includes wireline and wireless carriers and cable operators. • Strategic Enterprise: generally is comprised of financial services; national, federal, state, and local governments; research and educational institutions, and enterprises not represented in the Cloud vertical. The following table presents net revenues by customer vertical (in millions): Three Months Ended March 31, 2017 2016 Cloud $ 331.6 $ 264.8 Telecom/Cable 568.5 518.1 Strategic Enterprise 320.9 315.0 Total $ 1,221.0 $ 1,097.9 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, 2017 2016 Americas: United States $ 658.1 $ 579.0 Other 53.5 49.2 Total Americas 711.6 628.2 Europe, Middle East, and Africa 284.5 285.4 Asia Pacific 224.9 184.3 Total $ 1,221.0 $ 1,097.9

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Income before income taxes $ 140.6 $ 126.5 Income tax provision $ 31.8 $ 35.1 Effective tax rate 22.6 % 27.7 % The Company's effective tax rates during the three months ended March 31, 2017 and March 31, 2016, differ from the statutory rate primarily due to the benefit of the Section 199 deduction for U.S. production activities, the federal research and development (“R&D”) credit, and earnings in foreign jurisdictions, which are subject to lower tax rates. Additionally, the Company's effective tax rate for the three months ended March 31, 2017 was also impacted by the benefit of restructuring charges and excess tax benefits of share-based compensation. As of March 31, 2017 , the total amount of gross unrecognized tax benefits was $229.1 million , of which $198.0 million , if recognized, would favorably affect the Company's effective tax rate.

Net Income Per Share

Net Income Per Share	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Numerator: Net income $ 108.8 $ 91.4 Denominator: Weighted-average shares used to compute basic net income per share 380.9 383.2 Dilutive effect of employee stock awards 7.1 6.1 Weighted-average shares used to compute diluted net income per share 388.0 389.3 Net income per share Basic $ 0.29 $ 0.24 Diluted $ 0.28 $ 0.23 Anti-dilutive shares 1.6 4.0

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2017
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. Clock-Signal, Supplier Component Remediation Liability As of March 31, 2017 and December 31, 2016, the Company had approximately $18.0 million and $10.8 million , respectively, in other accrued liabilities on the Condensed Consolidated Balance Sheets for the expected remediation costs for certain products containing a defect in a clock-signal component manufactured by a third-party supplier. The Company has been advised by the component supplier that components may begin to fail after the product has been in operation for 18 months. The Company is in the process of working with its customers and the component supplier to implement a remediation. Guarantees The Company enters into agreements with customers that contain indemnification provisions relating to potential situations where claims could be alleged that the Company’s products solely, or in combination with other third party products, infringe the intellectual property rights of a third-party. As of March 31, 2017 , the Company recorded $14.4 million for such indemnification obligations in other accrued liabilities and other long-term liabilities on the Condensed Consolidated Balance Sheets. During the three months ended March 31, 2017, $15.0 million of indemnification obligations expired and were therefore released. Legal Proceedings Investigations The U.S. Securities and Exchange Commission ("SEC") and the U.S. Department of Justice ("DOJ") are conducting investigations into possible violations by the Company of the U.S. Foreign Corrupt Practices Act ("FCPA"). The Company is cooperating with these agencies regarding these matters. The Company’s Audit Committee, with the assistance of independent advisors, has been investigating and conducting a thorough review of possible violations of the FCPA, and has made recommendations for remedial measures, including employee disciplinary actions in foreign jurisdictions, which the Company has implemented and continues to implement. The Company is unable to predict the duration, scope or outcome of the SEC and DOJ investigations, but believes that an adverse outcome is reasonably possible. However, the Company is not able to estimate a reasonable range of possible loss. The SEC and/or DOJ could take action against the Company or the Company could agree to settle. In such event, the Company could be required to pay substantial fines and sanctions and/or implement additional remedial measures; in addition, it may be determined that the Company violated the FCPA. 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 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. 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 has not recorded any accrual for loss contingencies associated with such legal proceedings or the investigations discussed above.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Dividend Declaration On April 25, 2017, the Company announced that it had declared a cash dividend of $0.10 per share of common stock payable on June 22, 2017 to stockholders of record as of the close of business on June 1, 2017. Stock Repurchase Activities Subsequent to March 31, 2017, through the filing of this Report, the Company repurchased 1.6 million shares of its common stock, for an aggregate purchase price of $50.0 million at an average price of $30.57 per share, under the Stock Repurchase Program. Repurchases of approximately 1.0 million shares were settled prior to the filing of this Report and the remaining shares will be settled after the filing date. The Company has an aggregate of $544.7 million of authorized funds remaining under the Stock Repurchase Program, as of the filing date.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	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.
Recent accounting pronouncements	Except for the change in certain policies related to share-based compensation upon adoption of the accounting standard 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 Standard On January 1 2017, the Company adopted Financial Accounting Standards Board ("FASB") ASU No. 2016-09 (Topic 718) Compensation—Stock Compensation: Improvements to Employee Share-Based Payment Accounting ("ASU 2016-09"), which simplifies several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, forfeiture, statutory tax withholding requirements, and classification on the statement of cash flows. The impact of the adoption on the Company's condensed consolidated financial statements was as follows: • Forfeitures: The Company elected to account for forfeitures as they occur using a modified retrospective transition method, rather than estimating forfeitures, resulting in a cumulative-effect adjustment of $9.0 million , which increased the January 1, 2017 opening accumulated deficit balance on the Condensed Consolidated Balance Sheets. • Income tax accounting: The Company is also required to record excess tax benefits and tax deficiencies related to stock- based compensation as income tax benefit or expense in the statement of operations prospectively when share-based awards vest or are settled. Upon adoption, the Company recognized the previously unrecognized excess tax benefits using the modified retrospective transition method, which resulted in no impact to the January 1, 2017 opening accumulated deficit balance as previously unrecognized excess tax effects were fully offset by a valuation allowance. • Cash flow presentation of excess tax benefits: The Company is required to classify excess tax benefits along with other income tax cash flows as an operating activity either prospectively or retrospectively. The Company elected to apply the change in presentation to the statements of cash flows retrospectively and no longer classify the excess tax benefits from share-based compensation as a financing activity. There were no excess tax benefits reported in the Condensed Consolidated Statement of Cash Flows for the three months ended March 31, 2016. Recent Accounting Standards Not Yet Effective In March 2017, the FASB issued 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 ASU will not impact debt securities held at a discount. This standard is effective for annual reporting periods beginning after December 15, 2018, including interim reporting periods within those annual reporting periods, and is to be applied on a modified retrospective basis with early adoption permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In February 2017, the FASB issued ASU No. 2017-05 Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20): Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets which amends guidance on how entities account for the derecognition of a nonfinancial asset or an in substance nonfinancial asset that is not a business. This standard is effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods, and is to be applied on either a retrospective or modified retrospective basis with early adoption permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. 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 guidance 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. In January 2017, the FASB issued ASU No. 2017-01 (Topic 805) Business Combinations: Clarifying the Definition of a Business , which clarifies the definition of a business and assists entities with evaluating when a set of transferred assets and activities is a business. This ASU is effective for interim and annual periods beginning after December 15, 2017, with early adoption permitted. In November 2016, the FASB issued ASU No. 2016-18 (Topic 230) Statement of Cash Flow: Restricted Cash, which provides guidance on the classification of restricted cash to be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts on the statement of cash flows. The amendments of this ASU are effective for reporting periods beginning after December 15, 2017, with early adoption permitted. The standard must be applied retrospectively to all periods presented. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In October 2016, the FASB issued ASU No. 2016-16 (Topic 740) Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory, which requires the recognition of the income tax consequences of an intra-entity transfer of an asset, other than inventory, when the transfer occurs. ASU 2016-16 will be effective for annual and interim reporting periods beginning after December 15, 2017 and is to be applied on a modified retrospective basis. Early adoption is permitted. The Company is currently evaluating the impact of adoption on the Consolidated Financial Statements. In August 2016, the FASB issued ASU No. 2016-15 (Topic 230) Statement of Cash Flow: Classification of Certain Cash Receipts and Cash Payments, which clarifies how companies present and classify certain cash receipts and cash payments in the statement of cash flows. This pronouncement is effective for interim and annual reporting periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact that this standard will have on its Consolidated Statements of Cash Flows. 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. This pronouncement is 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 that this standard will have on its Consolidated Financial Statements and disclosures. In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases ("ASU 2016-02"), which requires recognition of lease assets and lease liabilities on the balance sheet by lessees for leases classified as operating leases with a lease term of more than twelve months. ASU 2016-02 should be applied on a modified retrospective basis and is effective for financial statements issued for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adoption of this standard, however it is expected to have a material impact on the Company's Consolidated Financial Statements and disclosures. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall: Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), which changes how entities measure equity investments and present changes in the fair value of financial liabilities measured under the fair value option. The guidance also updates certain presentation and disclosure requirements. ASU 2016-01 is effective for financial statements issued for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. The Company is currently evaluating the impact that ASU 2016-01will have on its Consolidated Financial Statements and disclosures. In May 2014, the FASB issued ASU No. 2014-09 (Topic 606) —Revenue from Contracts with Customers and several amendments thereafter (“ASU 2014-09”), which provides guidance for revenue recognition that will supersede the revenue recognition requirements in Topic 605, and most industry specific guidance. The core principle for ASU 2014-09 is that revenue is recognized when promised goods or services are transferred to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017. The Company intends to adopt ASU 2014-09 on January 1, 2018 retrospectively, applying the amendments to each prior reporting period presented and remains on schedule with its implementation and the preparation of its prior-period financial statements . Upon adoption, the Company expects a material impact to the opening balance sheet as of January 1, 2016 related to the cumulative effect of adopting the standard, primarily due to the application of the new guidance in the areas of distributor sales, software revenue, contract acquisition costs, variable consideration, and revenue allocation. The Company will continue to assess the impact of ASU 2014-09 including any changes to systems, processes and the control environment as it works through the adoption in 2017, and there remain areas still to be fully concluded upon. In addition, there are ongoing interpretive reviews, which may alter the Company's conclusions and the financial impact of ASU 2014-09. For further information, refer to Note 2, Significant Accounting Policies , in Notes to Consolidated Financial Statements in Item 8 of Part II of the Form 10-K.

Cash Equivalents and Investme25

Cash Equivalents and Investments (Tables)	3 Months Ended
	Mar. 31, 2017
Cash Equivalents and Investments [Abstract]
Unrealized gains and losses and fair value of available-for-sale and trading securities	The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of March 31, 2017 and December 31, 2016 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of March 31, 2017 Fixed income securities: Asset-backed securities $ 314.6 $ — $ (0.4 ) $ 314.2 Certificates of deposit 57.4 — — 57.4 Commercial paper 125.9 — — 125.9 Corporate debt securities 856.1 0.8 (1.5 ) 855.4 Foreign government debt securities 40.0 — (0.1 ) 39.9 Time deposits 245.8 — — 245.8 U.S. government agency securities 132.4 — (0.4 ) 132.0 U.S. government securities 380.7 0.1 (0.4 ) 380.4 Total fixed income securities 2,152.9 0.9 (2.8 ) 2,151.0 Money market funds 1,117.3 — — 1,117.3 Mutual Funds 8.3 — — 8.3 Publicly-traded equity securities 4.6 1.6 — 6.2 Total available-for-sale securities 3,283.1 2.5 (2.8 ) 3,282.8 Trading securities in mutual funds 22.6 — — 22.6 Total $ 3,305.7 $ 2.5 $ (2.8 ) $ 3,305.4 Reported as: Cash equivalents $ 1,429.9 $ — $ — $ 1,429.9 Restricted investments 73.8 — — 73.8 Short-term investments 741.0 1.8 (0.5 ) 742.3 Long-term investments 1,061.0 0.7 (2.3 ) 1,059.4 Total $ 3,305.7 $ 2.5 $ (2.8 ) $ 3,305.4 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2016 Fixed income securities: Asset-backed securities $ 303.0 $ 0.2 $ (0.2 ) $ 303.0 Certificates of deposit 66.1 — — 66.1 Commercial paper 147.7 — — 147.7 Corporate debt securities 846.5 0.4 (2.0 ) 844.9 Foreign government debt securities 34.0 — (0.1 ) 33.9 Time deposits 264.6 — — 264.6 U.S. government agency securities 127.0 — (0.3 ) 126.7 U.S. government securities 390.7 0.1 (0.4 ) 390.4 Total fixed income securities 2,179.6 0.7 (3.0 ) 2,177.3 Money market funds 592.2 — — 592.2 Mutual funds 8.0 — — 8.0 Publicly-traded equity securities 5.3 — (0.7 ) 4.6 Total available-for-sale securities 2,785.1 0.7 (3.7 ) 2,782.1 Trading securities in mutual funds 21.0 — — 21.0 Total $ 2,806.1 $ 0.7 $ (3.7 ) $ 2,803.1 Reported as: Cash equivalents $ 907.1 $ — $ — $ 907.1 Restricted investments 71.9 — — 71.9 Short-term investments 753.4 0.1 (1.2 ) 752.3 Long-term investments 1,073.7 0.6 (2.5 ) 1,071.8 Total $ 2,806.1 $ 0.7 $ (3.7 ) $ 2,803.1
Maturities of fixed income securities	The following table presents the contractual maturities of the Company's total fixed income securities as of March 31, 2017 (in millions): Amortized Cost Estimated Fair Value Due in less than one year $ 1,092.0 $ 1,091.7 Due between one and five years 1,060.9 1,059.3 Total $ 2,152.9 $ 2,151.0
Available-for-sale securities in unrealized loss position	The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of March 31, 2017 and December 31, 2016 (in millions): Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss As of March 31, 2017 Fixed income securities: Asset-backed securities $ 260.9 $ (0.4 ) $ — $ — $ 260.9 $ (0.4 ) Corporate debt securities 432.8 (1.4 ) 50.9 (0.1 ) 483.7 (1.5 ) Foreign government debt securities 23.3 (0.1 ) — — 23.3 (0.1 ) U.S. government agency securities 106.1 (0.4 ) — — 106.1 (0.4 ) U.S. government securities 272.8 (0.4 ) — — 272.8 (0.4 ) Total fixed income securities 1,095.9 (2.7 ) 50.9 (0.1 ) 1,146.8 (2.8 ) Total available-for-sale securities $ 1,095.9 $ (2.7 ) $ 50.9 $ (0.1 ) $ 1,146.8 $ (2.8 ) Less than 12 Months 12 Months or Greater Total Fair Value Unrealized Loss Fair Value Unrealized Loss Fair Value Unrealized Loss As of December 31, 2016 Fixed income securities: Asset-backed securities $ 122.2 $ (0.2 ) $ — $ — $ 122.2 $ (0.2 ) Corporate debt securities 470.8 (1.9 ) 76.7 (0.1 ) 547.5 (2.0 ) Foreign government debt securities 20.3 (0.1 ) — — 20.3 (0.1 ) U.S. government agency securities 106.7 (0.3 ) — — 106.7 (0.3 ) U.S. government securities 254.1 (0.4 ) — — 254.1 (0.4 ) Total fixed income securities 974.1 (2.9 ) 76.7 (0.1 ) 1,050.8 (3.0 ) Publicly-traded equity securities 4.6 (0.7 ) — — 4.6 (0.7 ) Total available-for-sale securities $ 978.7 $ (3.6 ) $ 76.7 $ (0.1 ) $ 1,055.4 $ (3.7 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2017
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 March 31, 2017 Using: Quoted Prices in Active Markets For Identical Assets Significant Other Observable Remaining Inputs Significant Other Unobservable Remaining Inputs (Level 1) (Level 2) (Level 3) Total Assets measured at fair value: Available-for-sale securities: Asset-backed securities $ — $ 314.2 $ — $ 314.2 Certificates of deposit — 57.4 — 57.4 Commercial paper — 125.9 — 125.9 Corporate debt securities — 855.4 — 855.4 Foreign government debt securities — 39.9 — 39.9 Money market funds 1,117.3 — — 1,117.3 Mutual funds 8.3 — — 8.3 Publicly-traded equity securities 6.2 — — 6.2 Time Deposits — 245.8 — 245.8 U.S. government agency securities — 132.0 — 132.0 U.S. government securities 337.3 43.1 — 380.4 Total available-for-sale securities 1,469.1 1,813.7 — 3,282.8 Trading securities in mutual funds 22.6 — — 22.6 Privately-held debt and redeemable preferred stock securities — — 42.3 42.3 Derivative assets: Foreign exchange contracts — 4.5 — 4.5 Total assets measured at fair value $ 1,491.7 $ 1,818.2 $ 42.3 $ 3,352.2 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (1.2 ) $ — $ (1.2 ) Total liabilities measured at fair value $ — $ (1.2 ) $ — $ (1.2 ) Total assets measured at fair value, reported as: Cash equivalents $ 1,074.4 $ 355.5 $ — $ 1,429.9 Restricted investments 73.8 — — 73.8 Short-term investments 186.8 555.5 — 742.3 Long-term investments 156.7 902.7 — 1,059.4 Prepaid expenses and other current assets — 4.5 — 4.5 Other long-term assets — — 42.3 42.3 Total assets measured at fair value $ 1,491.7 $ 1,818.2 $ 42.3 $ 3,352.2 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (1.2 ) $ — $ (1.2 ) Total liabilities measured at fair value $ — $ (1.2 ) $ — $ (1.2 ) Fair Value Measurements at December 31, 2016 Using: Quoted Prices in Active Markets For Identical Assets Significant Other Observable Remaining Inputs Significant Other Unobservable Remaining Inputs (Level 1) (Level 2) (Level 3) Total Assets measured at fair value: Available-for-sale securities: Asset-backed securities $ — $ 303.0 $ — $ 303.0 Certificates of deposit — 66.1 — 66.1 Commercial paper — 147.7 — 147.7 Corporate debt securities — 844.9 — 844.9 Foreign government debt securities — 33.9 — 33.9 Money market funds 592.2 — — 592.2 Mutual funds 8.0 — — 8.0 Publicly-traded equity securities 4.6 — — 4.6 Time Deposits — 264.6 — 264.6 U.S. government agency securities — 126.7 — 126.7 U.S. government securities 345.0 45.4 — 390.4 Total available-for-sale securities 949.8 1,832.3 — 2,782.1 Trading securities in mutual funds 21.0 — — 21.0 Privately-held debt and redeemable preferred stock securities — — 43.7 43.7 Derivative assets: Foreign exchange contracts — 0.9 — 0.9 Total assets measured at fair value $ 970.8 $ 1,833.2 $ 43.7 $ 2,847.7 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (4.9 ) $ — $ (4.9 ) Total liabilities measured at fair value $ — $ (4.9 ) $ — $ (4.9 ) Total assets measured at fair value, reported as: Cash equivalents $ 549.3 $ 357.7 $ — $ 907.0 Restricted investments 71.9 — — 71.9 Short-term investments 178.1 574.3 — 752.4 Long-term investments 171.5 900.3 — 1,071.8 Prepaid expenses and other current assets — 0.9 — 0.9 Other long-term assets — — 43.7 43.7 Total assets measured at fair value $ 970.8 $ 1,833.2 $ 43.7 $ 2,847.7 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (4.9 ) $ — $ (4.9 ) Total liabilities measured at fair value $ — $ (4.9 ) $ — $ (4.9 )

Derivative Instruments (Tables)

Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	The notional amount of the Company's foreign currency derivatives that are designated as cash flow hedges are summarized as follows (in millions): As of March 31, December 31, Cash flow hedges $ 222.8 $ 172.0

Goodwill and Purchased Intang28

Goodwill and Purchased Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	The following table presents goodwill activity (in millions): Balance as of December 31, 2016 $ 3,081.7 Other (*) (2.3 ) Balance as of March 31, 2017 $ 3,079.4 ________________________________ (*) Other primarily consists of certain purchase accounting adjustments related to previously completed business combinations.

Other Financial Information (Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2017
Other Financial Information [Abstract]
Inventories	Total inventory consisted of the following (in millions): As of March 31, December 31, Production and service materials $ 78.4 $ 75.6 Finished goods 20.0 19.9 Inventory $ 98.4 $ 95.5 Reported as: Prepaid expenses and other current assets $ 94.8 $ 91.4 Other long-term assets 3.6 4.1 Total $ 98.4 $ 95.5
Warranties	Changes during the three months ended March 31, 2017 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, 2016 $ 41.3 Provisions made during the period 12.3 Actual costs incurred during the period (8.1 ) Balance as of March 31, 2017 $ 45.5
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 $ 264.9 $ 302.4 Distributor inventory and other sell-through items 68.7 74.2 Deferred gross product revenue 333.6 376.6 Deferred cost of product revenue (52.3 ) (53.7 ) Deferred product revenue, net 281.3 322.9 Deferred service revenue 1,211.7 1,158.2 Total $ 1,493.0 $ 1,481.1 Reported as: Current $ 992.5 $ 1,032.0 Long-term 500.5 449.1 Total $ 1,493.0 $ 1,481.1
Other expense, net	Other expense, net, consisted of the following (in millions): Three Months Ended March 31, 2017 2016 Interest income $ 10.4 $ 7.9 Interest expense (25.3 ) (22.5 ) Gain (loss) on investments, net 1.2 (5.4 ) Other (2.0 ) (2.2 ) Other expense, net $ (15.7 ) $ (22.2 )

Restructuring Charges (Tables)

Restructuring Charges (Tables)	3 Months Ended
	Mar. 31, 2017
Restructuring and Related Activities [Abstract]
Schedule of restructuring liabilities	Restructuring liabilities are reported within other accrued liabilities on the Condensed Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liabilities primarily related to the 2017 Restructuring Plan initiated during the three months ended March 31, 2017 (in millions): December 31, 2016 (*) Charges Cash Payments Other March 31, Severance $ 0.7 $ 18.8 $ (5.2 ) $ 0.6 $ 14.9 Contract terminations and other 0.5 0.6 — — 1.1 Total $ 1.2 $ 19.4 $ (5.2 ) $ 0.6 $ 16.0 ________________________________ (*) Consists of costs in connection with a prior restructuring plan that is substantially complete.

Debt and Financing (Tables)

Debt and Financing (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Instruments [Abstract]
Long-term debt	The Company's long-term debt is summarized as follows (in millions, except percentages): As of March 31, 2017 Amount Effective Interest Rates Senior Notes ("Notes"): 3.125% fixed-rate notes, due February 2019 $ 350.0 3.36 % 3.300% fixed-rate notes, due June 2020 300.0 3.47 % 4.600% fixed-rate notes, due March 2021 300.0 4.69 % 4.500% fixed-rate notes, due March 2024, issued March 2014 350.0 4.63 % 4.500% fixed-rate notes, due March 2024, issued February 2016 150.0 4.87 % 4.350% fixed-rate notes, due June 2025 300.0 4.47 % 5.950% fixed-rate notes, due March 2041 400.0 6.03 % Total senior notes 2,150.0 Unaccreted discount and debt issuance costs (15.6 ) Total $ 2,134.4

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Schedule of Repurchase Agreements	The following table summarizes the Company's repurchases and retirements of its common stock under its Stock Repurchase Program (in millions, except per share amounts): Three Months Ended March 31, 2017 2016 Shares repurchased 4.5 3.1 Average price per share $ 28.03 $ 23.89 Amount repurchased $ 125.0 $ 75.0
Components of accumulated other comprehensive income, net of taxes	The components of accumulated other comprehensive loss, net of related taxes, for the three months ended March 31, 2017 were as follows (in millions): Unrealized Gains on Available-for- Sale Securities (1) Unrealized (Losses) Gains on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2016 $ 16.6 $ (4.5 ) $ (49.4 ) $ (37.3 ) Other comprehensive gains before reclassifications 1.5 5.3 7.9 14.7 Amount reclassified from accumulated other comprehensive loss (0.1 ) 1.1 — 1.0 Other comprehensive gains, net 1.4 6.4 7.9 15.7 Balance as of March 31, 2017 $ 18.0 $ 1.9 $ (41.5 ) $ (21.6 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive loss during the three months ended March 31, 2017 for realized gains on available-for-sale securities were insignificant, and were included in other expense, net, in the Condensed Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive loss during the three months ended March 31, 2017 for realized gains on cash flow hedges were insignificant, and were included within cost of revenues, research and development, sales and marketing, and general and administrative in the Condensed Consolidated Statements of Operations.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of share-based compensation, stock options, activity	The following table summarizes the Company’s stock option activity and related information as of and for the three months ended March 31, 2017 (in millions, except for per share amounts and years): Outstanding Options Number of Shares Weighted Average Exercise Price per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance as of December 31, 2016 2.4 $ 29.20 Exercised (0.2 ) 21.39 Expired/canceled (0.6 ) 30.63 Balance as of March 31, 2017 1.6 $ 29.83 1.8 $ 8.0 As of March 31, 2017: Vested and expected-to-vest options 1.6 $ 29.83 1.8 $ 8.0 Exercisable options 1.5 $ 30.82 1.5 $ 6.6
Schedule of nonvested share activity	The Company’s RSU, restricted stock award ("RSA"), and PSA activity and related information as of and for the three months ended March 31, 2017 were as follows (in millions, except per share amounts and years): Outstanding RSUs, RSAs, and PSAs Number of Shares Weighted Average Grant-Date Fair Value per Share Weighted Average Remaining Contractual Term (In Years) Aggregate Intrinsic Value Balance as of December 31, 2016 20.9 $ 24.05 RSUs granted (1)(3) 5.6 27.52 PSAs granted (2)(3) 0.6 27.32 RSUs vested (3.8 ) 24.14 RSAs vested (0.3 ) 22.69 PSAs vested (0.6 ) 24.41 RSUs canceled (0.4 ) 22.75 PSAs canceled (0.3 ) 24.33 Balance as of March 31, 2017 21.7 $ 24.90 1.4 $ 604.5 ________________________________ (1) Includes service-based and market-based RSUs. (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 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 0 to 0.6 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, 2017 , the Company declared a quarterly cash dividend of $0.10 per share of common stock on January 26, 2017 which was paid on March 22, 2017 to stockholders of record on March 1, 2017, in the aggregate amount of $38.0 million .
Schedule of employee service share-based compensation, allocation of recognized period costs	Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Condensed Consolidated Statements of Operations (in millions): Three Months Ended March 31, 2017 2016 Cost of revenues - Product $ 0.9 $ 1.9 Cost of revenues - Service 4.3 3.5 Research and development 34.8 32.3 Sales and marketing 15.3 9.4 General and administrative 6.7 4.7 Total $ 62.0 $ 51.8
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, 2017 2016 Stock options $ 0.1 $ 1.2 RSUs, RSAs, and PSAs 57.8 46.8 ESPP 4.1 3.8 Total $ 62.0 $ 51.8
Schedule of unrecognized compensation cost, nonvested awards	The unrecognized compensation cost recognized over a weighted-average period related to unvested stock options, RSUs, RSAs, and PSAs as of March 31, 2017 were as follows (in millions, except years): Unrecognized Compensation Cost Weighted Average Period (In Years) Stock options $ 1.0 2.1 RSUs, RSAs, and PSAs $ 424.7 1.8

Segments (Tables)

Segments (Tables)	3 Months Ended
	Mar. 31, 2017
Segment Reporting [Abstract]
Financial information for each segment	The following table presents net revenues by customer vertical (in millions): Three Months Ended March 31, 2017 2016 Cloud $ 331.6 $ 264.8 Telecom/Cable 568.5 518.1 Strategic Enterprise 320.9 315.0 Total $ 1,221.0 $ 1,097.9 The following table presents net revenues by product and service (in millions): Three Months Ended March 31, 2017 2016 Routing $ 521.6 $ 504.1 Switching 241.6 175.5 Security 65.7 73.4 Total product 828.9 753.0 Total service 392.1 344.9 Total $ 1,221.0 $ 1,097.9
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, 2017 2016 Americas: United States $ 658.1 $ 579.0 Other 53.5 49.2 Total Americas 711.6 628.2 Europe, Middle East, and Africa 284.5 285.4 Asia Pacific 224.9 184.3 Total $ 1,221.0 $ 1,097.9

Income Taxes (Tables)

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2017
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, 2017 2016 Income before income taxes $ 140.6 $ 126.5 Income tax provision $ 31.8 $ 35.1 Effective tax rate 22.6 % 27.7 %

Net Income Per Share (Tables)

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	The Company computed basic and diluted net income per share as follows (in millions, except per share amounts): Three Months Ended March 31, 2017 2016 Numerator: Net income $ 108.8 $ 91.4 Denominator: Weighted-average shares used to compute basic net income per share 380.9 383.2 Dilutive effect of employee stock awards 7.1 6.1 Weighted-average shares used to compute diluted net income per share 388.0 389.3 Net income per share Basic $ 0.29 $ 0.24 Diluted $ 0.28 $ 0.23 Anti-dilutive shares 1.6 4.0

Cash Equivalents and Investme37

Cash Equivalents and Investments - Available-For-Sale and Trading Securities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale securities:
Available-for-sale securities, amortized cost	$ 3,283.1	$ 2,785.1
Available-for-sale securities, gross unrealized gains	2.5	0.7
Available-for-sale securities, gross unrealized losses	(2.8)	(3.7)
Available-for-sale securities, estimated fair value	3,282.8	2,782.1
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	3,305.7	2,806.1
Total investments, gross unrealized gains	2.5	0.7
Total investments, gross unrealized losses	(2.8)	(3.7)
Total investments, estimated fair value	3,305.4	2,803.1
Cash equivalents [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	1,429.9	907.1
Total investments, gross unrealized gains	0	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	1,429.9	907.1
Restricted investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	73.8	71.9
Total investments, gross unrealized gains	0	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	73.8	71.9
Short-term investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	741	753.4
Total investments, gross unrealized gains	1.8	0.1
Total investments, gross unrealized losses	(0.5)	(1.2)
Total investments, estimated fair value	742.3	752.3
Long-term investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	1,061	1,073.7
Total investments, gross unrealized gains	0.7	0.6
Total investments, gross unrealized losses	(2.3)	(2.5)
Total investments, estimated fair value	1,059.4	1,071.8
Debt Securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	2,152.9	2,179.6
Available-for-sale securities, gross unrealized gains	0.9	0.7
Available-for-sale securities, gross unrealized losses	(2.8)	(3)
Available-for-sale securities, estimated fair value	2,151	2,177.3
Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	314.6	303
Available-for-sale securities, gross unrealized gains	0	0.2
Available-for-sale securities, gross unrealized losses	(0.4)	(0.2)
Available-for-sale securities, estimated fair value	314.2	303
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	57.4	66.1
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	57.4	66.1
Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	125.9	147.7
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	125.9	147.7
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	856.1	846.5
Available-for-sale securities, gross unrealized gains	0.8	0.4
Available-for-sale securities, gross unrealized losses	(1.5)	(2)
Available-for-sale securities, estimated fair value	855.4	844.9
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	40	34
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	(0.1)	(0.1)
Available-for-sale securities, estimated fair value	39.9	33.9
Time deposits [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	245.8	264.6
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	245.8	264.6
Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	132.4	127
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	(0.4)	(0.3)
Available-for-sale securities, estimated fair value	132	126.7
US government securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	380.7	390.7
Available-for-sale securities, gross unrealized gains	0.1	0.1
Available-for-sale securities, gross unrealized losses	(0.4)	(0.4)
Available-for-sale securities, estimated fair value	380.4	390.4
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	1,117.3	592.2
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	1,117.3	592.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	8.3	8
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	8.3	8
Trading securities:
Trading securities, amortized cost	22.6	21
Trading securities, gross unrealized gains	0	0
Trading securities, gross unrealized losses	0	0
Trading securities, estimated fair value	22.6	21
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	4.6	5.3
Available-for-sale securities, gross unrealized gains	1.6	0
Available-for-sale securities, gross unrealized losses	0	(0.7)
Available-for-sale securities, estimated fair value	$ 6.2	$ 4.6

Cash Equivalents and Investme38

Cash Equivalents and Investments - Maturities of Fixed Income Investments (Details) $ in Millions	Mar. 31, 2017USD ($)
Schedule of Fixed Income Securities Maturities [Abstract]
Amortized cost due within one year	$ 1,092
Amortized cost due between one and five years	1,060.9
Total investments, amortized cost	2,152.9
Estimated fair value due within one year	1,091.7
Estimated fair value due between one and five year	1,059.3
Total investments, estimated fair value	$ 2,151

Cash Equivalents and Investme39

Cash Equivalents and Investments - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)Investment	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)Investment
Cash Equivalents and Investments [Abstract]
Total investments in unrealized loss position | Investment	544		494
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	$ 114
Investments in privately-held companies	62.7		$ 62.7
Privately-held investment	20.4		$ 19
Impairment of privately-held investment	0	$ 5.1
Prepaid expenses and other current assets [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	20.5
Restricted Cash and Investments, Noncurrent [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments	$ 93.5

Cash Equivalents and Investme40

Cash Equivalents and Investments - Unrealized Loss on Available-for-Sale Securities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	$ 1,095.9	$ 978.7
Unrealized loss, less than 12 months	(2.7)	(3.6)
Fair value, 12 months or greater	50.9	76.7
Unrealized loss, 12 months or greater	(0.1)	(0.1)
Total fair value, available-for-sale investments in continuous unrealized loss position	1,146.8	1,055.4
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(2.8)	(3.7)
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	1,095.9	974.1
Unrealized loss, less than 12 months	(2.7)	(2.9)
Fair value, 12 months or greater	50.9	76.7
Unrealized loss, 12 months or greater	(0.1)	(0.1)
Total fair value, available-for-sale investments in continuous unrealized loss position	1,146.8	1,050.8
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(2.8)	(3)
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	260.9	122.2
Unrealized loss, less than 12 months	(0.4)	(0.2)
Fair value, 12 months or greater	0	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	260.9	122.2
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(0.4)	(0.2)
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	432.8	470.8
Unrealized loss, less than 12 months	(1.4)	(1.9)
Fair value, 12 months or greater	50.9	76.7
Unrealized loss, 12 months or greater	(0.1)	(0.1)
Total fair value, available-for-sale investments in continuous unrealized loss position	483.7	547.5
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(1.5)	(2)
Foreign government debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	23.3	20.3
Unrealized loss, less than 12 months	(0.1)	(0.1)
Fair value, 12 months or greater	0	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	23.3	20.3
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(0.1)	(0.1)
Government-sponsored enterprise obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	106.1	106.7
Unrealized loss, less than 12 months	(0.4)	(0.3)
Fair value, 12 months or greater	0	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	106.1	106.7
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	(0.4)	(0.3)
US government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	272.8	254.1
Unrealized loss, less than 12 months	(0.4)	(0.4)
Fair value, 12 months or greater	0	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	272.8	254.1
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	$ (0.4)	(0.4)
Publicly-traded equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months		4.6
Unrealized loss, less than 12 months		(0.7)
Fair value, 12 months or greater		0
Unrealized loss, 12 months or greater		0
Total fair value, available-for-sale investments in continuous unrealized loss position		4.6
Total unrealized loss, available-for-sale investments in continuous unrealized loss position		$ (0.7)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Available-for-sale securities:
Available-for-sale securities	$ 3,282.8	$ 2,782.1
Asset-backed Securities [Member]
Available-for-sale securities:
Available-for-sale securities	314.2	303
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities	57.4	66.1
Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities	125.9	147.7
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	855.4	844.9
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	39.9	33.9
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities	1,117.3	592.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities	8.3	8
Trading securities:
Trading securities	22.6	21
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities	6.2	4.6
Time deposits [Member]
Available-for-sale securities:
Available-for-sale securities	245.8	264.6
U.S. government agency securities [Member]
Available-for-sale securities:
Available-for-sale securities	132	126.7
US government securities [Member]
Available-for-sale securities:
Available-for-sale securities	380.4	390.4
Fair Value, Measurements, Recurring [Member]
Trading securities:
Privately-held debt and redeemable preferred stock securities	42.3	43.7
Derivative assets:
Total assets measured at fair value	3,352.2	2,847.7
Liabilities measured at fair value:
Other accrued liabilities	(1.2)	(4.9)
Total liabilities measured at fair value	(1.2)	(4.9)
Cash equivalents	1,429.9	907
Restricted investments	73.8	71.9
Short-term investments	742.3	752.4
Long-term investments	1,059.4	1,071.8
Prepaid expenses and other current assets	4.5	0.9
Other long-term assets	42.3	43.7
Fair Value, Measurements, Recurring [Member] | Foreign exchange contract [Member]
Derivative assets:
Foreign exchange contracts	4.5	0.9
Liabilities measured at fair value:
Derivative liabilities	(1.2)	(4.9)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Trading securities:
Privately-held debt and redeemable preferred stock securities	0	0
Derivative assets:
Total assets measured at fair value	1,491.7	970.8
Liabilities measured at fair value:
Other accrued liabilities	0	0
Total liabilities measured at fair value	0	0
Cash equivalents	1,074.4	549.3
Restricted investments	73.8	71.9
Short-term investments	186.8	178.1
Long-term investments	156.7	171.5
Prepaid expenses and other current assets	0	0
Other long-term assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Foreign exchange contract [Member]
Derivative assets:
Foreign exchange contracts	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Trading securities:
Privately-held debt and redeemable preferred stock securities	0	0
Derivative assets:
Total assets measured at fair value	1,818.2	1,833.2
Liabilities measured at fair value:
Other accrued liabilities	(1.2)	(4.9)
Total liabilities measured at fair value	(1.2)	(4.9)
Cash equivalents	355.5	357.7
Restricted investments	0	0
Short-term investments	555.5	574.3
Long-term investments	902.7	900.3
Prepaid expenses and other current assets	4.5	0.9
Other long-term assets	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Foreign exchange contract [Member]
Derivative assets:
Foreign exchange contracts	4.5	0.9
Liabilities measured at fair value:
Derivative liabilities	(1.2)	(4.9)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Trading securities:
Privately-held debt and redeemable preferred stock securities	42.3	43.7
Derivative assets:
Total assets measured at fair value	42.3	43.7
Liabilities measured at fair value:
Other accrued liabilities	0	0
Total liabilities measured at fair value	0	0
Cash equivalents	0	0
Restricted investments	0	0
Short-term investments	0	0
Long-term investments	0	0
Prepaid expenses and other current assets	0	0
Other long-term assets	42.3	43.7
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Foreign exchange contract [Member]
Derivative assets:
Foreign exchange contracts	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member]
Available-for-sale securities:
Available-for-sale securities	314.2	303
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	314.2	303
Fair Value, Measurements, Recurring [Member] | Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities	57.4	66.1
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	57.4	66.1
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities	125.9	147.7
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	125.9	147.7
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	855.4	844.9
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	855.4	844.9
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	39.9	33.9
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	39.9	33.9
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities	1,117.3	592.2
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	1,117.3	592.2
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities	8.3	8
Trading securities:
Trading securities	22.6	21
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	8.3	8
Trading securities:
Trading securities	22.6	21
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Trading securities:
Trading securities	0	0
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Trading securities:
Trading securities	0	0
Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities	6.2	4.6
Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	6.2	4.6
Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Time deposits [Member]
Available-for-sale securities:
Available-for-sale securities	245.8	264.6
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	245.8	264.6
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | U.S. government agency securities [Member]
Available-for-sale securities:
Available-for-sale securities	132	126.7
Fair Value, Measurements, Recurring [Member] | U.S. government agency securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | U.S. government agency securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	132	126.7
Fair Value, Measurements, Recurring [Member] | U.S. government agency securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | US government securities [Member]
Available-for-sale securities:
Available-for-sale securities	380.4	390.4
Fair Value, Measurements, Recurring [Member] | US government securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	337.3	345
Fair Value, Measurements, Recurring [Member] | US government securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	43.1	45.4
Fair Value, Measurements, Recurring [Member] | US government securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] | Available-for-sale securities [Member]
Available-for-sale securities:
Available-for-sale securities	3,282.8	2,782.1
Fair Value, Measurements, Recurring [Member] | Available-for-sale securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	1,469.1	949.8
Fair Value, Measurements, Recurring [Member] | Available-for-sale securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	1,813.7	1,832.3
Fair Value, Measurements, Recurring [Member] | Available-for-sale securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investment	$ 20,400,000	$ 19,000,000
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investment, fair value	42,300,000	43,700,000
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchases of privately-held investments	0
Unrealized gain (loss) on investments	0
Privately-held investment, fair value	42,300,000	43,700,000
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and Long-term debt, fair value	2,253,300,000	2,215,700,000
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investment, fair value	0	0
Cost Method Investment, Privately Held Companies [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investment		1,600,000
Privately-held investment, fair value		0
Junos Pulse
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note receivable	132,900,000	132,900,000
Junos Pulse | Prepaid expenses and other current assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note receivable	$ 75,000,000	$ 75,000,000

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Cash flow hedging [Member] | Cash flow hedges [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	$ 222.8	$ 172

Derivative Instruments - Cash F

Derivative Instruments - Cash Flow Hedges and Offsetting of Derivatives (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Foreign exchange contract [Member] | Cash flow hedging [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	$ 7	$ 3

Goodwill and Purchased Intang45

Goodwill and Purchased Intangible Assets - Goodwill (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2016	$ 3,081.7
Other	(2.3)
Balance as of March 31, 2017	$ 3,079.4

Goodwill and Purchased Intang46

Goodwill and Purchased Intangible Assets - Purchased Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Purchased intangible assets, net	$ 125.9		$ 130.2
Amortization of intangible assets	$ 4.3	$ 3.3

Other Financial Information - I

Other Financial Information - Inventories, Net (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Schedule Of Inventory [Line Items]
Production and service materials	$ 78.4	$ 75.6
Finished goods	20	19.9
Inventory	98.4	95.5
Prepaid expenses and other current assets [Member]
Schedule Of Inventory [Line Items]
Inventory	94.8	91.4
Other Noncurrent Assets [Member]
Schedule Of Inventory [Line Items]
Inventory	$ 3.6	$ 4.1

Other Financial Information - O

Other Financial Information - Other Long Term Assets (Details) - USD ($) $ in Millions	May 05, 2017	Mar. 31, 2017	Mar. 31, 2016	May 08, 2017	Dec. 31, 2016	Oct. 01, 2014
Junos Pulse
Other Financial Information [Line Items]
Note receivable carrying value						$ 125
Consideration						230.7
Cash Consideration						105.7
Working capital adjustment						$ 19.3
Note receivable		$ 132.9			$ 132.9
Interest income		2.7	$ 2.7
Prepaid expenses and other current assets [Member] | Junos Pulse
Other Financial Information [Line Items]
Note receivable		$ 75			$ 75
Subsequent Event
Other Financial Information [Line Items]
Note receivable				$ 58
Subsequent Event | Junos Pulse
Other Financial Information [Line Items]
Proceeds from collection of notes receivable	$ 75

Other Financial Information - W

Other Financial Information - Warranties (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance as of December 31, 2016	$ 41.3
Provisions made during the period	12.3
Adjustments related to pre-existing warranties	(8.1)
Balance as of March 31, 2017	$ 45.5

Other Financial Information - D

Other Financial Information - Deferred Revenue (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Deferred product revenue:
Total deferred revenue	$ 1,493	$ 1,481.1
Reported as:
Current	992.5	1,032
Long-term	500.5	449.1
Total deferred revenue	1,493	1,481.1
Sales Revenue, Product, Net [Member]
Deferred product revenue:
Undelivered product commitments and other product deferrals	264.9	302.4
Distributor inventory and other sell-through items	68.7	74.2
Deferred gross product revenue	333.6	376.6
Deferred cost of product revenue	(52.3)	(53.7)
Total deferred revenue	281.3	322.9
Reported as:
Total deferred revenue	281.3	322.9
Sales Revenue, Service, Net [Member]
Deferred product revenue:
Total deferred revenue	1,211.7	1,158.2
Reported as:
Total deferred revenue	$ 1,211.7	$ 1,158.2

Other Financial Information -51

Other Financial Information - Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other Financial Information [Abstract]
Interest income	$ 10.4	$ 7.9
Interest expense	(25.3)	(22.5)
Gain (loss) on investments, net	1.2	(5.4)
Other	(2)	(2.2)
Other expense, net	$ (15.7)	$ (22.2)

Restructuring Charges (Details)

Restructuring Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	$ 1.2
Charges	19.4	$ 0
Cash Payments	(5.2)
Other	0.6
Restructuring liability, ending balance	16
Severance [Member]
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0.7
Charges	18.8
Cash Payments	(5.2)
Other	0.6
Restructuring liability, ending balance	14.9
Severance [Member] | 2017 Restructuring Plan [Member]
Restructuring Reserve [Roll Forward]
Charges	18.8
Contract terminations and other [Member]
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	0.5
Charges	0.6
Cash Payments	0
Other	0
Restructuring liability, ending balance	1.1
Contract terminations and other [Member] | 2017 Restructuring Plan [Member]
Restructuring Reserve [Roll Forward]
Charges	$ 0.6

Debt and Financing (Details)

Debt and Financing (Details) $ in Millions	Mar. 31, 2017USD ($)
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,150
Unaccreted discount and debt issuance costs	(15.6)
Long-term Debt	$ 2,134.4
Redemption percent due to change in control	101.00%
Fixed Rate Note Due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 350
Effective Interest Rates	3.36%
Long-term debt, stated interest rate	3.125%
Fixed rate note due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 300
Effective Interest Rates	3.47%
Long-term debt, stated interest rate	3.30%
Fixed rate note due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 300
Effective Interest Rates	4.69%
Long-term debt, stated interest rate	4.60%
Fixed Rate Note Due 2024, Issued March 2014 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 350
Effective Interest Rates	4.63%
Long-term debt, stated interest rate	4.50%
Fixed Rate Note Due 2024, Issued February 2016 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 150
Effective Interest Rates	4.87%
Long-term debt, stated interest rate	4.50%
Fixed rate note due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 300
Effective Interest Rates	4.47%
Long-term debt, stated interest rate	4.35%
Fixed rate note due 2041 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 400
Effective Interest Rates	6.03%
Long-term debt, stated interest rate	5.95%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Line of Credit	$ 0

Debt and Financing - Revolving

Debt and Financing - Revolving Credit Facility (Details) - Revolving Credit Facility [Member]	Jun. 27, 2014USD ($)
Line of Credit Facility [Line Items]
Revolving credit facility limit	$ 500,000,000
Revolving credit facility, additional borrowing capacity	$ 200,000,000
Base Rate [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.00%
Base Rate [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Eurodollar [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.90%
Eurodollar [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.50%

Debt and Financing - Customer F

Debt and Financing - Customer Financing Arrangements (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Sale of receivable	$ 25.4
Proceeds from sale and collection of receivables	23.1
Receivables from sale of receivables	$ 15.9	$ 13.6
Minimum [Member]
Debt Instrument [Line Items]
Number of days due from receivable	30 days
Maximum [Member]
Debt Instrument [Line Items]
Number of days due from receivable	90 days

Equity - Cash Dividends on Shar

Equity - Cash Dividends on Shares of Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 26, 2017	Mar. 31, 2017	Mar. 31, 2016
Stockholders' Equity Note [Abstract]
Cash dividends declared per common stock (in dollars per share)	$ 0.1	$ 0.10	$ 0.10
Common stock dividends paid		$ 38

Equity - Stock Repurchase Activ

Equity - Stock Repurchase Activities (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Feb. 28, 2017	Oct. 31, 2014	Feb. 28, 2014
2014 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount			$ 4,400,000,000		$ 2,100,000,000
Additional amount authorized under Stock Repurchase Plan			$ 500,000,000	$ 1,800,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 594,700,000
Stock repurchased (in shares)	4.5	3.1
Average price per share (in dollars per share)	$ 28.03	$ 23.89
Amount repurchased	$ 125,000,000	$ 75,000,000
Stock Repurchase Program 2014, Accelerated Share Repurchase [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount					$ 1,200,000,000

Equity - Components of Accumula

Equity - Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Other comprehensive gains before reclassifications	$ 14.7
Amount reclassified from accumulated other comprehensive income	1
Other comprehensive gains, net	15.7
Unrealized Gains (Losses) on Available-for- Sale Securities [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2016	16.6
Other comprehensive gains before reclassifications	1.5
Amount reclassified from accumulated other comprehensive income	(0.1)
Other comprehensive gains, net	1.4
Balance as of March 31, 2017	18
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2016	(4.5)
Other comprehensive gains before reclassifications	5.3
Amount reclassified from accumulated other comprehensive income	1.1
Other comprehensive gains, net	6.4
Balance as of March 31, 2017	1.9
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2016	(49.4)
Other comprehensive gains before reclassifications	7.9
Amount reclassified from accumulated other comprehensive income	0
Other comprehensive gains, net	7.9
Balance as of March 31, 2017	(41.5)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2016	(37.3)
Balance as of March 31, 2017	$ (21.6)

Employee Benefit Plans (Details

Employee Benefit Plans (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)$ / sharesshares
Number of Shares
Balance at beginning of period (in shares)	2.4
Exercised (in shares)	(0.2)
Expired/canceled (in shares)	(0.6)
Balance at end of period (in shares)	1.6
Weighted Average Exercise Price per Share
Balance at beginning of period (in dollars per share) | $ / shares	$ 29.20
Exercised (in dollars per share) | $ / shares	21.39
Expired/canceled (in dollars per share) | $ / shares	30.63
Balance at end of period (in dollars per share) | $ / shares	$ 29.83
Weighted average remaining contractual term at end of period	1 year 9 months 18 days
Aggregate intrinsic value at end of period | $	$ 8
Vested or expected-to-vest options at end of period (in shares)	1.6
Vested or expected-to-vest options, weighted average exercise price at end of period (in dollars per share) | $ / shares	$ 29.83
Vested and expected-to-vest options, weighted average remaining contractual term at end of period	1 year 9 months 18 days
Vested or expected-to-vest options, aggregate intrinsic value at end of period | $	$ 8
Exercisable options at end of period (in shares)	1.5
Exercisable options, weighted average exercise price at end of period (in dollars per share) | $ / shares	$ 30.82
Exercisable options, weighted average remaining contractual term at end of period	1 year 6 months
Exercisable options, aggregate intrinsic value at end of period | $	$ 6.6
Equity incentive plan 2015 [Member]
Share-Based Compensation Plans
Number of shares available for future issuance	11.6
Employee stock purchase plan 2008 [Member]
Share-Based Compensation Plans
Number of shares available for future issuance	3.4

Employee Benefit Plans - Equity

Employee Benefit Plans - Equity Instruments Other Than Options (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 26, 2017	Mar. 31, 2017	Mar. 31, 2016
Weighted Average Grant-Date Fair Value per Share
Cash dividends declared per common stock (in dollars per share)	$ 0.1	$ 0.10	$ 0.10
Common stock dividends paid		$ 38
Employee stock purchase plan 2008 [Member]
Employee Stock Purchase Plan
Expiration period for ESPP		6 months
Stock issued during period, shares, employee stock purchase plans (in shares)		1,500,000	1,300,000
Average price of common stock, per share (in dollars per share)		$ 19.21	$ 20.06
RSUs, RSAs, and PSAs [Member]
Number of Shares
Balance at beginning of period (in shares)		20,900,000
Balance at end of period (in shares)		21,700,000
Weighted Average Grant-Date Fair Value per Share
Balance at beginning of period (in dollars per share)		$ 24.05
Balance at end of period (in dollars per share)		$ 24.90
Weighted Average Remaining Contractual Term (In Years)		1 year 4 months 21 days
Aggregate Intrinsic Value		$ 604.5
Restricted Stock Units (RSUs) [Member]
Number of Shares
Granted (in shares)		5,600,000
Vested (in shares)		(3,800,000)
Canceled (in shares)		(400,000)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$ 27.52
Vested (in dollars per share)		24.14
Canceled (in dollars per share)		$ 22.75
Performance shares (PSAs)
Number of Shares
Granted (in shares)		600,000
Vested (in shares)		(600,000)
Canceled (in shares)		(300,000)
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$ 27.32
Vested (in dollars per share)		24.41
Canceled (in dollars per share)		$ 24.33
Aggregate number of shares subject to PSAs granted		400,000
Minimum shares to be issued on achievement of performance goals in respect of PSAs		0
Maximum shares to be issued on achievement of performance goals in respect of PSAs		600,000
Restricted stock awards (RSAs)
Number of Shares
Vested (in shares)		(300,000)
Weighted Average Grant-Date Fair Value per Share
Vested (in dollars per share)		$ 22.69

Employee Benefit Plans - Share

Employee Benefit Plans - Share Based Compensation by Cost and Expense Categories (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 62	$ 51.8
Stock Options [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	0.1	1.2
RSUs, RSAs, and PSAs [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	57.8	46.8
ESPP [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	4.1	3.8
Cost of Revenues, Product [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	0.9	1.9
Cost of Revenues, Service [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	4.3	3.5
Research and Development [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	34.8	32.3
Sales and Marketing [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	15.3	9.4
General and Administrative [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$ 6.7	$ 4.7

Employee Benefit Plans - Shar62

Employee Benefit Plans - Share Based Compensation by Share Based Payment Award Types (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Stock Options [Member]
Unrecognized Compensation Cost [Abstract]
Unrecognized Compensation Cost	$ 1
Weighted Average Period (In Years)	2 years 1 month 6 days
RSUs, RSAs, and PSAs [Member]
Unrecognized Compensation Cost [Abstract]
Unrecognized Compensation Cost	$ 424.7
Weighted Average Period (In Years)	1 year 9 months 18 days

Segments (Details)

Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment	1
Product	$ 828.9	$ 753
Service	392.1	344.9
Total net revenues	1,221	1,097.9
Routing [Member]
Segment Reporting Information [Line Items]
Product	521.6	504.1
Switching [Member]
Segment Reporting Information [Line Items]
Product	241.6	175.5
Security [Member]
Segment Reporting Information [Line Items]
Product	$ 65.7	$ 73.4

Segments - Revenues by Customer

Segments - Revenues by Customer Vertical (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total net revenues	$ 1,221	$ 1,097.9
Cloud
Segment Reporting Information [Line Items]
Total net revenues	331.6	264.8
Telecom/Cable
Segment Reporting Information [Line Items]
Total net revenues	568.5	518.1
Strategic Enterprise
Segment Reporting Information [Line Items]
Total net revenues	$ 320.9	$ 315

Segments - Geographic (Details)

Segments - Geographic (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Total net revenues	$ 1,221	$ 1,097.9
United States
Segment Reporting Information [Line Items]
Total net revenues	658.1	579
Other
Segment Reporting Information [Line Items]
Total net revenues	53.5	49.2
Total Americas
Segment Reporting Information [Line Items]
Total net revenues	711.6	628.2
Europe, Middle East, and Africa
Segment Reporting Information [Line Items]
Total net revenues	284.5	285.4
Asia Pacific
Segment Reporting Information [Line Items]
Total net revenues	$ 224.9	$ 184.3

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Tax Disclosure [Abstract]
Income before income taxes	$ 140.6	$ 126.5
Income tax provision	$ 31.8	$ 35.1
Effective tax rate	22.60%	27.70%
Unrecognized tax benefits	$ 229.1
Unrecognized tax benefits that would impact effective tax rate	$ 198

Net Income Per Share (Details)

Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net income
Net income	$ 108.8	$ 91.4
Denominator:
Weighted-average shares used to compute basic net income per share (in shares)	380.9	383.2
Dilutive effect of employee stock awards (in shares)	7.1	6.1
Weighted-average shares used to compute diluted net income per share (in shares)	388	389.3
Net income per share
Basic, in dollars per share	$ 0.29	$ 0.24
Diluted, in dollars per share	$ 0.28	$ 0.23
Anti-dilutive shares	1.6	4

Commitments and Contingencies -

Commitments and Contingencies - Commitments (Details) - Damages from Product Defects [Member] - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Loss Contingencies [Line Items]
Supplier component remediation liability	$ 18	$ 10.8
Supplier component remediation, estimated period that components may begin to fail	18 months

Commitments and Contingencies69

Commitments and Contingencies - Guarantees (Details) - Indemnification Agreement [Member] $ in Millions	3 Months Ended
	Mar. 31, 2017USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$ 14.4
Guarantor obligations, reversal of accrual recorded previouslyy	$ 15

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Apr. 25, 2017	Jan. 26, 2017	May 08, 2017	Mar. 31, 2017	Mar. 31, 2016
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollars per share)		$ 0.1		$ 0.10	$ 0.10
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollars per share)	$ 0.1
Common Stock | Subsequent Event
Subsequent Event [Line Items]
Stock repurchased during period (in shares)			1.6
Shares repurchased during the period			$ 50
Average price per share (in dollars per share)			$ 30.57
Shares settled (in shares)			1
Stock repurchase program, remaining authorized repurchase amount			$ 544.7