Juniper Networks (JNPR) 10-K 19 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 12, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	JUNIPER NETWORKS INC
Entity Central Index Key	1,043,604
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
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		382,604,514
Entity Public Float			$ 9,668

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	Oct. 22, 2015	Jul. 23, 2015	Apr. 23, 2015	Jan. 27, 2015	Oct. 23, 2014	Jul. 22, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net revenues:
Product							$ 973.9	$ 925.4	$ 899.7	$ 764.1	$ 794	$ 809.5	$ 929.2	$ 876	$ 3,563.1	$ 3,408.7	$ 3,519.9
Service							345.7	323.2	322.5	303.3	307.6	316.4	300.3	294.1	1,294.7	1,218.4	1,149.2
Total net revenues							1,319.6	1,248.6	1,222.2	1,067.4	1,101.6	1,125.9	1,229.5	1,170.1	4,857.8	4,627.1	4,669.1
Cost of revenues:
Product							346.5	322.6	311.7	288.8	310.9	290	359.3	326.6	1,269.6	1,286.8	1,276.6
Service							130.7	128.6	129	121.3	115.6	121.1	122	123.4	509.6	482.1	451.1
Total cost of revenues							477.2	451.2	440.7	410.1	426.5	411.1	481.3	450	1,779.2	1,768.9	1,727.7
Gross margin							842.4	797.4	781.5	657.3	675.1	714.8	748.2	720.1	3,078.6	2,858.2	2,941.4
Operating expenses:
Research and development							247.2	247	251.6	248.7	233.5	253.2	255.5	264	994.5	1,006.2	1,043.2
Sales and marketing							255.9	235.3	232.4	220.2	243	249.2	258	273.4	943.8	1,023.6	1,075.9
General and administrative							60.3	57.1	56.3	55.2	40.6	55	60.6	74.9	228.9	231.1	217.3
Restructuring and other (benefits) charges							(0.1)	0	(1.9)	1.4	9.8	(15)	58.2	114	(0.6)	167	39.1
Impairment of goodwill											850	0	0	0	0	850	0
Total operating expenses							563.3	539.4	538.4	525.5	1,376.9	542.4	632.3	726.3	2,166.6	3,277.9	2,375.5
Operating income (loss)							279.1	258	243.1	131.8	(701.8)	172.4	115.9	(6.2)	912	(419.7)	565.9
Other (expense) income, net							(18.5)	(8.4)	(17.1)	(15.8)	7.4	(6.8)	178.6	154.2	(59.8)	333.4	(40.4)
Income (loss) before income taxes							260.6	249.6	226	116	(694.4)	165.6	294.5	148	852.2	(86.3)	525.5
Income tax provision							62.8	51.9	68	35.8	75.2	62	73.4	37.4	218.5	248	85.7
Net income (loss)							$ 197.8	$ 197.7	$ 158	$ 80.2	$ (769.6)	$ 103.6	$ 221.1	$ 110.6	$ 633.7	$ (334.3)	$ 439.8
Net income (loss) per share:
Basic (in dollars per share)							$ 0.52	$ 0.52	$ 0.41	$ 0.20	$ (1.81)	$ 0.23	$ 0.47	$ 0.23	$ 1.62	$ (0.73)	$ 0.88
Diluted (in dollars per share)							0.51	0.51	0.40	0.19	(1.81)	0.23	0.46	0.22	$ 1.59	$ (0.73)	$ 0.86
Shares used in computing net income per share:
Basic (in shares)															390.6	457.4	501.8
Diluted (in shares)															399.4	457.4	510.3
Cash dividends declared per share of common stock (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0	$ 0	$ 0.40	$ 0.20	$ 0

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 633.7	$ (334.3)	$ 439.8
Available-for-sale securities:
Unrealized gains on available-for-sale securities, net of tax (provision) of ($6.5), ($29.5) and ($37.9) for 2015, 2014 and 2013, respectively	9.1	48.7	65.1
Reclassification adjustment for realized net gains on available-for- sale securities included in net income (loss), net of tax provision of zero, $61.8 and $0.4 for 2015, 2014 and 2013, respectively	(0.5)	(106.5)	(1)
Net change on available-for-sale securities, net of taxes	8.6	(57.8)	64.1
Cash flow hedges:
Unrealized (losses) gain on cash flow hedges, net of tax (provision) benefit of ($0.4), ($0.7) and $1.7 for 2015, 2014 and 2013, respectively	(6.7)	(4.1)	0.7
Reclassification adjustment for realized loss (gains) on cash flow hedges included in net income (loss), net of tax provision (benefit) of zero, $1.1 and ($0.8) for 2015, 2014 and 2013, respectively	9.6	(2.3)	(1.5)
Net change on cash flow hedges, net of taxes	2.9	(6.4)	(0.8)
Change in foreign currency translation adjustments	(16.9)	(14.2)	(3.4)
Other comprehensive (losses) income, net of tax	(5.4)	(78.4)	59.9
Comprehensive income (loss)	$ 628.3	$ (412.7)	$ 499.7

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income Parenthetical - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Tax (provision) on change in unrealized gains on available-for-sale securities	$ (6.5)	$ (29.5)	$ (37.9)
Tax provision on reclassification adjustment for realized net gains on available-for-sale securities included in net income	0	61.8	0.4
Tax (provision) benefit on change in unrealized (losses) gains on cash flow hedges	(0.4)	(0.7)	1.7
Tax provision (benefit) on reclassification adjustment for realized losses (gains) included in net income	$ 0	$ 1.1	$ (0.8)

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 1,420.9	$ 1,639.6
Short-term investments	527.1	332.2
Accounts receivable, net of allowance for doubtful accounts of $9.3 and $4.7 as of December 31, 2015 and 2014, respectively	780.7	598.9
Prepaid expenses and other current assets	183.7	239.9
Total current assets	2,912.4	2,810.6
Property and equipment, net	1,021	904.3
Long-term investments	1,244.2	1,133.1
Restricted cash and investments	36.2	46
Purchased intangible assets, net	33.9	62.4
Goodwill	2,981.3	2,981.5
Other long-term assets	390.2	343.5
Total assets	8,619.2	8,281.4
Current liabilities:
Short-term debt	299.9	0
Accounts payable	159.3	234.6
Accrued compensation	269.5	225
Deferred revenue	822.9	780.8
Other accrued liabilities	250.3	273
Total current liabilities	1,801.9	1,513.4
Long-term debt	1,648.8	1,349
Long-term deferred revenue	345.2	294.9
Long-term income tax payable	187.3	177.5
Other long-term liabilities	61.6	27.5
Total liabilities	$ 4,044.8	$ 3,362.3
Commitments and contingencies (Note 16)
Juniper Networks 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; 384.0 shares and 416.2 shares issued and outstanding as of December 31, 2015 and 2014, respectively	0	0
Additional paid-in capital	8,334.8	8,794
Accumulated other comprehensive loss	(19.2)	(13.8)
Accumulated deficit	(3,741.2)	(3,861.1)
Total stockholders' equity	4,574.4	4,919.1
Total liabilities and stockholders' equity	$ 8,619.2	$ 8,281.4

Consolidated Balance Sheets Par

Consolidated Balance Sheets Parenthetical - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheet Parenthetical [Abstract]
Allowance for doubtful accounts receivable, current	$ 9.3	$ 4.7
Convertible preferred stock - par value (in USD 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 USD per share)	$ 0.00001	$ 0.00001
Common stock - shares authorized	1,000,000,000	1,000,000,000
Common stock - shares issued	384,000,000	416,200,000
Common stock - outstanding	384,000,000	416,200,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Cash Flows [Abstract]
Net income (loss)	$ 633.7	$ (334.3)	$ 439.8
Adjustments to reconcile consolidated net income to net cash provided by operating activities:
Share-based compensation expense	217.3	240	244.6
Depreciation, amortization, and accretion	176.5	186.1	189.9
Restructuring and other charges	(4.1)	208.5	47.5
Deferred income taxes	(14.6)	(16.9)	72.2
Impairment of goodwill	0	850	0
Gain on sale of Junos Pulse	0	(19.6)	0
(Gain) loss on investments, net	(6.8)	(167.9)	(11.3)
Gain on legal settlement, net	0	(121.1)	0
Excess tax benefits from share-based compensation	(12.3)	(9.4)	(1.9)
Loss on disposal of fixed assets	0.4	1.7	1.4
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	(218.9)	(16.8)	(139.9)
Prepaid expenses and other assets	(43.5)	(10.1)	(126)
Accounts payable	(80.2)	38.3	(8.9)
Accrued compensation	46.6	(46)	(5.4)
Income tax payable	104.3	51	(38.5)
Other accrued liabilities	1.8	(115.2)	36.5
Deferred revenue	92.3	45.1	145.9
Net cash provided by operating activities	892.5	763.4	845.9
Cash flows from investing activities:
Purchases of property and equipment	(210.3)	(192.9)	(230)
Proceeds from sale of Junos Pulse	0	105.7	0
Purchases of available-for-sale investments	(1,486.4)	(2,440.7)	(1,776)
Proceeds from sales of available-for-sale investments	861.6	2,627.7	1,167.2
Proceeds from maturities of available-for-sale investments	319.8	337.6	334.6
Purchases of trading investments	(4.4)	(4.1)	(3.7)
Proceeds from the sales of privately-held investments	10.6	4.9	9.4
Purchases of privately-held investments	(5.4)	(21.7)	(41.3)
Payment for business acquisitions, net of cash and cash equivalents acquired	(3.5)	(27.1)	(10)
Purchase of licensed software	0	0	(10)
Changes in restricted cash	9.3	44.6	(1.2)
Net cash used in investing activities	(508.7)	434	(561)
Cash flows from financing activities:
Proceeds from issuance of common stock	121.2	159.8	141.7
Purchases and retirement of common stock	(1,153.6)	(2,262.5)	(577.8)
Issuance of long-term debt, net	594.6	346.5	0
Payment for capital lease obligation	0.4	(0.4)	(1.4)
Customer financing arrangements	0	9	33.9
Excess tax benefits from share-based compensation	12.3	9.4	1.9
Payment of cash dividends	(156.3)	(86)	0
Net cash (used in) provided by financing activities	(581.4)	(1,824.2)	(401.7)
Effect of foreign currency exchange rates on cash and cash equivalents	(21.1)	(17.6)	(7)
Net (decrease) increase in cash and cash equivalents	(218.7)	(644.4)	(123.8)
Cash and cash equivalents at beginning of period	1,639.6	2,284	2,407.8
Cash and cash equivalents at end of period	1,420.9	1,639.6	2,284
Supplemental disclosures of cash flow information:
Cash paid for interest, net of amounts capitalized	80.6	44.9	57.4
Cash paid (received) for income taxes, net	128.3	206	105.1
Non-cash investing activities:
Receipt of a promissory note in connection with the sale of Junos Pulse	$ 0	$ 125	$ 0

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Noncontrolling Interest [Member]
Number of shares, Beginning balance at Dec. 31, 2012		508.4
Stockholders' equity, Beginning balance at Dec. 31, 2012	$ 6,999.5		$ 9,905.7	$ 4.7	$ (2,911.4)	$ 0.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	439.8				439.8
Other comprehensive income (loss), net	59.9			59.9
Issuance of common stock (in number of shares)		16
Issuance of common stock	142.2		142.2
Dissolution of non-controlling interest	(0.5)					(0.5)
Repurchase and retirement of common stock (in number of shares)		(29.2)
Repurchase and retirement of common stock	(577.8)		(418.1)		(159.7)
Share-based compensation expense	244.9		244.9
Tax effects from employee stock option plans			(5.8)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(5.8)
Number of shares, Ending balance at Dec. 31, 2013		495.2
Stockholders' equity, Ending balance at Dec. 31, 2013	7,302.2		9,868.9	64.6	(2,631.3)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	(334.3)				(334.3)
Other comprehensive income (loss), net	(78.4)			(78.4)
Issuance of common stock (in number of shares)		17.7
Issuance of common stock	159.1		159.1
Repurchase and retirement of common stock (in number of shares)		(96.7)
Repurchase and retirement of common stock	(2,262.5)		(1,367)		(895.5)
Share-based compensation expense	240		240
Tax effects from employee stock option plans			(21)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(21)
Payment of cash dividends	(86)		(86)
Number of shares, Ending balance at Dec. 31, 2014		416.2
Stockholders' equity, Ending balance at Dec. 31, 2014	4,919.1		8,794	(13.8)	(3,861.1)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Consolidated net income (loss)	633.7				633.7
Other comprehensive income (loss), net	(5.4)			(5.4)
Issuance of common stock (in number of shares)		13.6
Issuance of common stock	121.2		121.2
Repurchase and retirement of common stock (in number of shares)		(45.8)
Repurchase and retirement of common stock	(1,153.6)		(639.8)		(513.8)
Share-based compensation expense	217.3		217.3
Tax effects from employee stock option plans			(1.6)
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(1.6)
Payment of cash dividends	(156.3)		(156.3)
Number of shares, Ending balance at Dec. 31, 2015		384
Stockholders' equity, Ending balance at Dec. 31, 2015	$ 4,574.4		$ 8,334.8	$ (19.2)	$ (3,741.2)	$ 0

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation Description of Business Juniper Networks, Inc. (the “Company” or “Juniper”) designs, develops, and sells products and services for high-performance networks, to enable customers to build scalable, reliable, secure and cost-effective networks for their businesses, while achieving agility, efficiency and value through automation. The Company serves the high-performance networking requirements for global service providers, cloud environments, enterprises, governments, and research and public sector organizations that view the network as critical to their success. In addition to the Company's products, the Company offers technical support and professional services, as well as education and training programs to its customers. Together, the high-performance product and service offerings help the Company's customers convert legacy networks that provide commoditized services into more valuable assets that provide differentiation, value, and increased performance, reliability, and security to end-users. Basis of Presentation The Consolidated Financial Statements, which include the Company and its wholly-owned subsidiaries, are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). All intercompany balances and transactions have been eliminated. Certain amounts in the prior-years Consolidated Financial Statements have been reclassified to conform to the current-year presentation, including the adoption of Accounting Standards Update ("ASU") No. 2015-17, Balance Sheet Classification of Deferred Taxes , which requires that deferred tax assets and liabilities be classified as noncurrent on the Consolidated Balance Sheets. The guidance is effective for all annual periods, and interim periods within those annual periods, beginning after December 15, 2016, with early adoption permitted. The Company has early adopted this standard effective December 31, 2015, retrospectively. The adoption resulted in a $261.0 million and $147.0 million decrease in current deferred tax assets and a decrease of $207.0 million and $107.4 million in other long-term liabilities as of December 31, 2015 and 2014, respectively on the Consolidated Balance Sheets. The adoption of ASU No. 2015-17 had no impact to the Company’s Consolidated Statements of Operations.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Use of Estimates The preparation of the financial statements and related disclosures in conformity with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Consolidated Financial Statements and the accompanying notes. The Company bases its estimates and assumptions on current facts, historical experience, and various other factors that it believes are reasonable under the circumstances, to determine the carrying values of assets and liabilities that are not readily apparent from other sources. To the extent there are material differences between the Company's estimates and the actual results, the Company's future consolidated results of operation may be affected. Cash, Cash Equivalents and Investments Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, demand deposits with banks, highly liquid investments in money market funds, commercial paper, government securities, certificates of deposit, and corporate debt securities, which are readily convertible into cash. All highly liquid investments purchased with original maturities of three months or less are classified as cash and cash equivalents. Investments in Available-for-Sale and Trading Securities The Company's investments in publicly-traded debt and equity securities are classified as available-for-sale. Available-for-sale investments are initially recorded at cost and periodically adjusted to fair value in the Consolidated Balance Sheets. Unrealized gains and losses on these investments are reported as a separate component of accumulated other comprehensive income. Realized gains and losses are determined based on the specific identification method and are reported in the Consolidated Statements of Operations. The Company periodically evaluates its investments to determine if impairment charges are required. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time the investment has been in a loss position, the extent to which the fair value has been less than the Company's cost basis, the investment's financial condition, and near-term prospects of the investee. If the Company determines that the decline in an investment's fair value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. The Company's non-qualified compensation plan is invested in mutual funds which are classified as trading securities and reported at fair value in the Consolidated Balance Sheets. The realized and unrealized holding gains and losses are reported in the Consolidated Statements of Operations. Privately-Held Investments The Company has privately-held investments included in other long-term assets in the 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. The investments carried at cost are adjusted for any impairment, as the Company does not have a controlling interest and does not have the ability to exercise significant influence over these companies. These investments are inherently high risk as the market for technologies or products manufactured by these companies are usually in their early stages at the time of the investment by the Company and such markets may never be significant. The Company measures the fair value of privately-held investments using an analysis of the financial conditions and near term prospects of the investees, including recent financing activities and their capital structure. Realized gains and losses, if any, are reported in the Consolidated Statements of Operations. Fair Value Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it transacts, and considers assumptions that market participants would use when pricing the asset or liability. The Company applies the following fair value hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. These inputs are valued using market based approaches. Level 3 – Inputs are unobservable inputs based on the Company’s assumptions. These inputs, if any, are valued using internal financial models. Derivatives The Company uses derivatives to partially offset its market exposure to fluctuations in certain foreign currencies. The Company does not enter into derivatives for speculative or trading purposes. The Company uses foreign currency forward contracts to hedge certain forecasted foreign currency transactions relating to operating expenses. These derivatives are designated as cash flow hedges. Execution of these cash flow hedge derivatives typically occurs every month with maturities of one year or less. These derivatives are carried at fair value and the effective portion of the derivative's gain or loss is initially reported as a component of accumulated other comprehensive income, and upon occurrence of the forecasted transaction, is subsequently reclassified into the costs of services or operating expense line item to which the hedged transaction relates. The Company records any ineffectiveness of the hedging instruments in other (expense) income, net, on its Consolidated Statements of Operations. Cash flows from such hedges are classified as operating activities. All amounts within other comprehensive income are expected to be reclassified into earnings within the next twelve months. The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in non-functional currencies. These derivatives are carried at fair value with changes recorded in other (expense) income, net in the Consolidated Statements of Operations in the same period as the changes in the fair value from the re-measurement of the underlying assets and liabilities. Cash flows from such derivatives are classified as operating activities. These foreign exchange forward contracts have maturities of one year or less. Inventory Inventory consists primarily of component parts to be used in the manufacturing process and finished goods in-transit, and is stated at the lower of cost or market. Cost is computed using standard cost, which approximates actual cost, on a first-in, first-out basis. A charge is recorded to cost of product when inventory is determined to be in excess of anticipated demand or considered obsolete. At the point of loss recognition, a new, lower-cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in the restoration or increase in the newly established cost basis. Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 3 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 5 to 40 Leasehold improvements Lease term, not to exceed 10 years Construction in progress is related to the construction or development of property and equipment that have not yet been placed in service for their intended use. Depreciation for computers, equipment, software, furniture and fixtures commences once they are placed in service. Depreciation for buildings, land and leasehold improvements commences once they are ready for their intended use. Goodwill and Other Long-Lived Assets Goodwill represents the future economic benefits arising from other assets acquired in a business combination or an acquisition that are not individually identified and separately recorded. The excess of the purchase price over the estimated fair value of net assets of businesses acquired in a business combination is recognized as goodwill. Goodwill is tested for impairment annually during the fourth quarter or more frequently if certain circumstances indicate the carrying value of goodwill is impaired. A qualitative assessment is first made to determine whether it is necessary to quantitatively test goodwill for impairment. This initial assessment includes, among others, consideration of macroeconomic conditions and financial performance. If the qualitative assessment indicates that it is more likely than not that an impairment exists, a quantitative analysis is performed by comparing the estimated fair values of our reporting units with their respective carrying values, including goodwill. An impairment loss is recognized to the extent that the carrying amount of goodwill exceeds the asset's implied fair value. Other intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized but are assessed for potential impairment annually or when events or circumstances indicate that their carrying amounts might be impaired. Long-lived assets, such as property, plant, and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group, to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. An impairment charge is recognized by the amount by which the carrying amount of the asset, or asset group, exceeds its fair value. The Company amortizes intangible assets with estimable useful lives on a straight-line basis over their useful lives. Revenue Recognition Revenue is recognized when all of the following criteria have been met: • Persuasive evidence of an arrangement exists. The Company generally relies upon sales contracts or agreements, and customer purchase orders to determine the existence of an arrangement. • Delivery has occurred. The Company uses shipping terms and related documents, or written evidence of customer acceptance, when applicable, to verify delivery or performance. • Sales price is fixed or determinable. The Company assesses whether the sales price is fixed or determinable based on the payment terms and whether the sales price is subject to refund or adjustment. • Collectability is reasonably assured. The Company assesses collectability based on creditworthiness of customers as determined by its credit checks, their payment histories, or changes in circumstances that indicate that collectability is not reasonably assured. When sales arrangements contain multiple elements the Company allocates revenue to each element based on a selling price hierarchy. The selling price for a deliverable is based on either vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”) if VSOE is not available, or estimated selling price (“ESP”) if neither VSOE nor TPE is available. The Company then recognizes revenue on each deliverable in accordance with its policies for product and service revenue recognition. VSOE of selling price is based on the price charged when the element is sold separately. In determining VSOE, the Company requires that a substantial majority of the selling prices fall within a reasonable range based on historical discounting trends for specific products and services. TPE of selling price is established by evaluating largely interchangeable competitor products or services in stand-alone sales to similar situated customers. However, as the Company's products contain a significant element of proprietary technology and its solutions offer substantially different features and functionality, the comparable pricing of third-party products with similar functionality typically cannot be obtained and therefore TPE is not used. ESP is established considering multiple factors including, but not limited to pricing practices in different geographies and through different sales channels, gross margin objectives, internal costs, competitor pricing strategies, and industry technology lifecycles. In multiple element arrangements where software deliverables are included, revenue is allocated to each separate unit of accounting for each of the non-software deliverables and to the software deliverables as a group using the relative selling prices of each of the deliverables in the arrangement based on the aforementioned selling price hierarchy. If the arrangement contains more than one software deliverable, the arrangement consideration allocated to the software deliverables as a group is then allocated to each software deliverable using the residual method when VSOE of fair value of the undelivered items exists. Under the residual method, the amount of revenue allocated to delivered elements equals the total arrangement consideration less the aggregate fair value of any undelivered elements. If VSOE of one or more undelivered items does not exist, revenue from the entire arrangement is deferred and recognized at the earlier of: (i) delivery of those elements or (ii) when fair value can be established unless maintenance services is the only undelivered element, in which case, the entire arrangement fee is recognized ratably over the maintenance service period. The Company limits the amount of revenue recognition for delivered elements to the amount that is not contingent on the future delivery of products or services or subject to customer-specific return or refund privileges. The Company records reductions to revenue for estimated product returns and pricing adjustments, such as rebates and price protection, in the same period that the related revenue is recorded. The amount of these reductions is based on historical sales returns and price protection credits, specific criteria outlined in rebate agreements, and other factors known at the time. A portion of the Company's sales is made through distributors under agreements allowing for pricing credits or rights of return. As reliable estimates of these credits or returns cannot be made, product revenue on sales made through these distributors is recognized upon sell-through as reported by the distributors to the Company. Deferred revenue on shipments to distributors reflects the effects of distributor pricing credits given and the amount of gross margin expected to be realized upon sell-through. Deferred revenue is recorded net of the related product costs of revenue. Service revenues include revenue from maintenance, training, and professional services. Maintenance is offered under renewable contracts. Revenue from maintenance service contracts is deferred and recognized ratably over the contractual support period, which is generally one to three years . Revenue from training and professional services is recognized as services are completed or ratably over the contractual period, which is generally one year or less. Allowance for Doubtful Accounts The allowance for doubtful accounts is based on the Company's assessment of the collectability of customer accounts. The Company regularly reviews its receivables that remain outstanding past their applicable payment terms and establishes an allowance by considering factors such as historical experience, credit quality, and age of the accounts receivable balances, and current economic conditions that may affect a customer's ability to pay. Warranty Reserves The Company generally offers a one -year warranty on most of its hardware products, and a 90 -day warranty on the media that contains the software embedded in the products. Warranty costs are recognized as part of the Company's cost of sales based on associated material costs, logistics costs, labor costs, and overhead at the time revenue is recognized. Material costs are estimated primarily based upon the historical costs to repair or replace product returns within the warranty period. Labor, logistics and overhead costs are estimated primarily based upon historical trends in the cost to support customer cases within the warranty period. Contract Manufacturer Liabilities The Company establishes a liability for non-cancelable, non-returnable purchase commitments with its contract manufacturers for carrying charges, quantities in excess of its demand forecasts, or obsolete material charges for components purchased by the contract manufacturers to meet the Company’s demand forecast or customer orders. The demand forecasts are based upon historical trends and analysis from the Company's sales and marketing organizations, adjusted for overall market conditions. Research and Development Costs to research, design, and develop the Company's products are expensed as incurred. Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins when a product's technological feasibility has been established and ends when a product is available for general release to customers. Generally, the Company's products are released soon after technological feasibility has been established. As a result, costs incurred between achieving technological feasibility and product general availability have not been significant. The Company capitalizes costs associated with internal-use software systems during the application development stage. Such capitalized costs include external direct costs utilized in developing or obtaining the applications and payroll and payroll-related costs for employees, who are directly associated with the development of the applications. Advertising Advertising costs are charged to sales and marketing expense as incurred. Advertising expense was $20.2 million , $19.2 million , and $20.1 million , for 2015 , 2014 , and 2013 , respectively. Foreign Currency Assets and liabilities of foreign operations with non-U.S. Dollar functional currency are translated to U.S. Dollars using exchange rates in effect at the end of the period. Revenue and expenses are translated to U.S. Dollars using average exchange rates for the period. The resulting translation adjustments are included in the Company’s Consolidated Balance Sheets in the stockholders’ equity section as a component of accumulated other comprehensive income. For the Company's international subsidiaries in which the functional currency is the U.S. dollar, the Company records foreign exchange gains and losses for assets and liabilities denominated in non-U.S. dollar currencies. These remeasurement adjustments are recorded in other (expense) income, net in the Consolidated Statements of Operations. Loss Contingencies The Company is subject to the possibility of various loss contingencies arising in the ordinary course of business. Management considers the likelihood of loss related to an asset, or the incurrence of a liability, as well as its ability to reasonably estimate the amount of loss, in determining loss contingencies. An estimated loss contingency is accrued when it is probable that an asset has been impaired or a liability has been incurred and the amount of loss can be reasonably estimated. The Company regularly evaluates current information available to determine whether such accruals should be adjusted and whether new accruals are required. Share-Based Compensation The Company measures and recognizes compensation cost for all share-based awards made to employees and directors, including employee stock options, stock awards, stock units, and employee stock purchases related to the Employee Stock Purchase Plan ("ESPP"). Share-based compensation expense is based on the fair value of the underlying awards and amortized on a straight-line basis, net of estimated forfeitures. The Company utilizes the Black-Scholes-Merton (“BSM”) option-pricing model to estimate the fair value of its stock options and ESPP shares. The BSM model requires various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, expected life, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected life of the Company’s stock options and ESPP. The expected life of a stock option is based on historical experience of employee exercises and post-vesting termination behavior as well as the potential effect from options that have not been exercised. The expected life of ESPP approximates the offering period. The Company determines the fair value of its restricted stock units ("RSUs"), restricted stock awards ("RSAs"), and performance share awards ("PSAs") based on the closing market price of the Company’s common stock on the date of grant, adjusted by the present value of the expected dividend. For market-based RSUs, the Company estimates the fair value and derived service period using the Monte Carlo simulation option pricing model ("Monte Carlo model"). The determination of the grant date fair value and derived service periods using the Monte Carlo model is affected by the Company's stock price as well as various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the contractual life of the Company's market-based RSUs. Provision for Income Taxes Deferred tax assets and liabilities are recognized for the expected tax consequences of temporary differences between the tax bases of assets and liabilities and their reported amounts. Valuation allowances are recorded to reduce deferred tax assets to the amount that will more likely than not be realized. The Company accounts for uncertainty in income taxes using a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company classifies the liability for unrecognized tax benefits as current to the extent that the Company anticipates payment (or receipt) of cash within one year . Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes. Concentrations of Risk Financial instruments that subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, investments, and accounts receivable. The Company invests only in high-quality credit instruments and maintains its cash, cash equivalents and available-for-sale investments in fixed income securities with several high-quality institutions. Deposits held with banks, including those held in foreign branches of global banks, may exceed the amount of insurance provided on such deposits. These deposits may be redeemed upon demand and, therefore, bear minimal credit risk. The Company’s derivatives expose it to credit risk to the extent that counterparties may be unable to meet the terms of the agreement. To mitigate concentration of risk related to its derivatives, the Company establishes counterparty limits to major credit-worthy financial institutions. In addition, the potential risk of loss with any one counterparty resulting from this type of credit risk is monitored and the derivatives transacted with these entities are relatively short in duration. Therefore, the Company does not expect material losses as a result of defaults by counterparties. Generally, credit risk with respect to accounts receivable is diversified due to the number of entities comprising the Company's customer base and their dispersion across different geographic locations throughout the world. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. During the years ended December 31, 2015 , 2014 , and 2013 , no single customer accounted for 10% or more of net revenues. The Company relies on sole suppliers for certain of its components such as application-specific integrated circuits ("ASICs") and custom sheet metal. Additionally, the Company relies primarily on a limited number of significant independent contract manufacturers and outside design manufacturers for the production of its products. The inability of any supplier or manufacturer to fulfill supply requirements of the Company could negatively impact future operating results. Recent Accounting Pronouncements In January 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), which requires equity investments to be measured at fair value with changes in fair value recognized in net income and simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment. Entities may choose a practical expedient, to estimate the fair value of certain equity securities that do not have readily determinable fair value. If the practical expedient is elected, these investments would be recorded at cost, less impairment and subsequently adjusted for observable price changes. 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 September 2015, the FASB issued ASU No. 2015-16 (Topic 805) - Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments ("ASU 2015-16") , which replaces the requirement that an acquirer in a business combination account for measurement period adjustments retrospectively, with a requirement that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. ASU 2015-16 requires the entity to record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendment requires an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. ASU 2015-16 is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendment should be applied prospectively to adjustments to provisional amounts that occur after the effective date of the guidance, with early adoption permitted for financial statements that have not been issued. The adoption of this standard will apply upon execution of a business combination. In July 2015, the FASB issued ASU No. 2015-11 (Subtopic 330) - Simplifying the Measurement of Inventory ("ASU 2015-11"), which provides guidance to companies who account for inventory using either the first-in, first-out ("FIFO") or average cost methods. The guidance states that companies should measure inventory at the lower of cost and net realizable value. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. ASU 2015-11 is effective for fiscal years beginning after December 15, 2016. Early adoption is permitted. The adoption of this standard will not have a significant impact on the Company's Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-05 (Subtopic 350-40) - Customer's Accounting for Fees Paid in a Cloud Computing Arrangement ("ASU 2015-05"), which provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The ASU also eliminates the existing requirement that customers analogize to the guidance on leases in ASC 840 to determine the asset acquired in a software licensing arrangement. Instead, customers will account for software licenses that are obtained for internal-use in the same manner as licenses of other intangible assets. ASU 2015-05 is effective for fiscal years, beginning after December 15, 2015. Early adoption is permitted. The Company plans to adopt the ASU prospectively for all new transactions entered into or materially modified after the date of adoption. In April 2015, the FASB issued ASU No. 2015-03 (Subtopic 835-30) - Simplifying the Presentation of Debt Issuance Costs ("ASU 2015-03"), which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard would reduce the debt issuance cost asset on the Company's Consolidated Balance Sheet by approximately $11.0 million and correspondingly reduce its debt liabilities by approximately $11.0 million . The Company plans to adopt this standard in the first quarter of 2016. The adoption of this standard will not have an impact to the Consolidated Statement of Operations. In August 2015, the FASB issued ASU No. 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements ("ASU 2015-03") . ASU 2015-15 provides additional guidance to ASU 2015-03, which did not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. The amendment states that an entity may defer and present debt issuance costs associated with line-of-credit arrangements as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The adoption of ASU 2015-15 will not have an impact on the Company's Consolidated Financial Statements. In November 2014, the FASB issued ASU No. 2014-16 (Topic 815) - Derivatives and Hedging ("ASU 2014-16), which provides clarification on how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features in evaluating the h

Business Combinations

Business Combinations	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Business Combinations	Business Combinations The Company's Consolidated Financial Statements include the operating results of acquired businesses from the date of each acquisition. Pro forma results of operations for these acquisitions have not been presented as the financial impact to the Company's consolidated results of operations, both individually and in aggregate, is not material. Additional information, if any, existing as of the acquisition dates but unknown to the Company may become known during the remainder of the measurement period, not to exceed 12 months from the acquisition date, which may result in changes to the amounts and allocations recorded. The Company did not complete any business combinations in 2015 and completed one business combination in 2014 and one business combination in 2013 . Cash consideration, including the fair value of vested share-based awards assumed, if any, for acquisitions in 2014 and 2013 , was approximately $28.7 million and $10.0 million , respectively. The following table presents the purchase consideration allocations for these acquisitions based upon acquisition-date fair values, including cash and cash equivalents acquired (in millions): 2014 Acquisition 2013 Acquisition Net tangible assets acquired $ — $ 0.1 Net liabilities acquired (2.7 ) — Intangible assets acquired 17.8 9.9 Goodwill 13.6 — Total $ 28.7 $ 10.0 The goodwill recognized for the 2014 acquisition was primarily attributable to expected synergies and was not deductible for U.S. federal income tax purposes. 2014 Acquisition On January 7, 2014, the Company acquired 100% of the equity securities of WANDL, Inc. ("WANDL"), for $28.7 million of cash and stock consideration. WANDL, a provider of software solutions for advanced planning, management, design and optimization of next-generation multi-layer networks, provides the Company with technology and experience in traffic engineering, multi-layer optimization and path computation to help service provider customers optimize the performance and cost of their networks. Under the terms of the purchase agreement, the Company assumed unvested share-based awards for employees with a fair value of $34.9 million , which were granted in contemplation of future services and are being expensed as share-based compensation over the remaining service period. Intangible Assets Acquired The following table presents details of the Company's intangible assets acquired through the business combination completed during the twelve months ended December 31, 2014 (in millions, except years): Weighted Average Estimated Useful Life (In Years) Amount Existing technology 7 $ 10.7 Customer relationships 7 6.0 Trade name 4 0.6 Backlog 1 0.2 Non-compete agreements 2 0.3 Total 7 $ 17.8 2013 Acquisition During 2013, the Company completed a business combination for approximately $10.0 million in cash consideration of which $0.1 million was allocated to net tangible assets acquired and $9.9 million to intangible assets. Intangible assets acquired consisted of existing technology with a weighted-average estimated useful life of five years .

Cash Equivalents and Investment

Cash Equivalents and Investments	12 Months Ended
	Dec. 31, 2015
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 December 31, 2015 and December 31, 2014 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2015 Fixed income securities: Asset-backed securities $ 312.2 $ — $ (0.5 ) $ 311.7 Certificates of deposit 9.6 — — 9.6 Commercial paper 17.7 — — 17.7 Corporate debt securities 913.8 0.2 (2.6 ) 911.4 Foreign government debt securities 16.5 — — 16.5 Government-sponsored enterprise obligations 204.1 — (0.4 ) 203.7 U.S. government securities 278.0 — (0.4 ) 277.6 Total fixed income securities 1,751.9 0.2 (3.9 ) 1,748.2 Money market funds 29.7 — — 29.7 Mutual funds 6.1 0.1 — 6.2 Publicly-traded equity securities 8.7 0.8 (0.7 ) 8.8 Total available-for-sale securities 1,796.4 1.1 (4.6 ) 1,792.9 Trading securities in mutual funds (1) 17.7 — — 17.7 Total $ 1,814.1 $ 1.1 $ (4.6 ) $ 1,810.6 Reported as: Cash equivalents $ 3.4 $ — $ — $ 3.4 Restricted investments 35.8 0.1 — 35.9 Short-term investments 527.2 0.9 (1.0 ) 527.1 Long-term investments 1,247.7 0.1 (3.6 ) 1,244.2 Total $ 1,814.1 $ 1.1 $ (4.6 ) $ 1,810.6 ________________________________ (1) Balance includes the Company's non-qualified deferred compensation plan assets. Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2014 Fixed income securities: Asset-backed securities $ 269.3 $ — $ (0.3 ) $ 269.0 Certificates of deposit 10.6 — — 10.6 Commercial paper 20.3 — — 20.3 Corporate debt securities 738.6 0.5 (1.1 ) 738.0 Foreign government debt securities 24.6 — — 24.6 Government-sponsored enterprise obligations 162.2 — (0.1 ) 162.1 U.S. government securities 246.1 — (0.1 ) 246.0 Total fixed income securities 1,471.7 0.5 (1.6 ) 1,470.6 Money market funds 594.2 — — 594.2 Mutual funds 3.9 0.1 — 4.0 Publicly-traded equity securities 2.1 — (0.1 ) 2.0 Total available-for-sale securities 2,071.9 0.6 (1.7 ) 2,070.8 Trading securities in mutual funds (1) 16.3 — — 16.3 Total $ 2,088.2 $ 0.6 $ (1.7 ) $ 2,087.1 Reported as: Cash equivalents $ 576.6 $ — $ — $ 576.6 Restricted investments 45.2 — — 45.2 Short-term investments 332.2 0.2 (0.2 ) 332.2 Long-term investments 1,134.2 0.4 (1.5 ) 1,133.1 Total $ 2,088.2 $ 0.6 $ (1.7 ) $ 2,087.1 _______________________________ (1) Balance includes the Company's non-qualified deferred compensation plan assets. The following table presents the contractual maturities of the Company's total fixed income securities as of December 31, 2015 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due in less than one year $ 504.1 $ 0.1 $ (0.3 ) $ 503.9 Due between one and five years 1,247.8 0.1 (3.6 ) 1,244.3 Total $ 1,751.9 $ 0.2 $ (3.9 ) $ 1,748.2 The Company had 682 and 437 investments in unrealized loss positions as of December 31, 2015 and December 31, 2014 , 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 December 31, 2015 , 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 years ended December 31, 2015 , 2014 , and 2013 . 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 years ended December 31, 2015 and December 31, 2013 , the Company did not recognize other-than-temporary impairments associated with its available-for-sale equity securities. During the year ended December 31, 2014 , the Company determined that certain available-for-sale equity securities were other-than temporarily impaired, resulting in an impairment charge of $1.1 million that was recorded within other (expense) income, net, in the Consolidated Statement of Operations. During the years ended December 31, 2015 and December 31, 2013 , there were no material gross realized gains or losses from available-for-sale securities and trading securities. During the year ended December 31, 2014 , gross realized gains from available-for-sale securities were $166.8 million and gross realized losses were not material. There were no material gross realized gains or losses from trading securities during the year ended December 31, 2014 . The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of December 31, 2015 and December 31, 2014 (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 December 31, 2015 Fixed income securities: Asset-backed securities $ 274.2 $ (0.4 ) $ 30.8 $ (0.1 ) $ 305.0 $ (0.5 ) Certificates of deposit (1) 3.3 — — — 3.3 — Corporate debt securities 687.9 (2.3 ) 58.9 (0.3 ) 746.8 (2.6 ) Foreign government debt securities (1) 9.5 — — — 9.5 — Government-sponsored enterprise obligations 185.3 (0.4 ) — — 185.3 (0.4 ) U.S. government securities 259.3 (0.4 ) — — 259.3 (0.4 ) Total fixed income securities 1,419.5 (3.5 ) 89.7 (0.4 ) 1,509.2 (3.9 ) Publicly-traded equity securities 2.1 (0.7 ) — — 2.1 (0.7 ) Total available-for sale securities $ 1,421.6 $ (4.2 ) $ 89.7 $ (0.4 ) $ 1,511.3 $ (4.6 ) ________________________________ (1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2015 . 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, 2014 Fixed income securities: Asset-backed securities $ 221.9 $ (0.3 ) $ — $ — $ 221.9 $ (0.3 ) Corporate debt securities 515.9 (1.1 ) — — 515.9 (1.1 ) Foreign government debt securities (1) 24.6 — — — 24.6 — Government-sponsored enterprise obligations 113.8 (0.1 ) — — 113.8 (0.1 ) U.S. government securities 189.0 (0.1 ) — — 189.0 (0.1 ) Total fixed income securities 1,065.2 (1.6 ) — — 1,065.2 (1.6 ) Publicly-traded equity securities 2.0 (0.1 ) — — 2.0 (0.1 ) Total available-for-sale securities $ 1,067.2 $ (1.7 ) $ — $ — $ 1,067.2 $ (1.7 ) ________________________________ (1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2014 . Restricted Cash and Investments The Company classifies certain cash and investments as restricted cash and investments on its Consolidated Balance Sheets for: (i) amounts held in escrow accounts, as required in connection with certain acquisitions completed between 2005 and 2014; (ii) the India Gratuity Trust and Israel Retirement Trust, which cover statutory severance obligations in the event of termination of any of the Company's India and Israel employees, respectively; and (iii) the Directors and Officers indemnification trust ("D&O Trust"). The restricted investments are designated as available-for-sale securities. Privately-Held Investments As of December 31, 2015 and December 31, 2014 , the carrying values of the Company's privately-held investments of $102.4 million and $89.9 million , respectively, were included in other long-term assets in the Consolidated Balance Sheets. As of December 31, 2015 and December 31, 2014 , the carrying value of the privately-held investments includes debt and redeemable preferred stock securities of $60.2 million and $47.5 million , respectively. For the year ended December 31, 2015 , the Company recorded $11.4 million in other comprehensive (loss) income for unrealized gains and no unrealized losses associated with its privately-held debt and redeemable preferred stock securities. During the year ended December 31, 2014 , there were $15.0 million of unrealized gains and no unrealized losses associated with privately-held securities and no unrealized gains or losses on redeemable preferred stock in other comprehensive (loss) income. The Company reviews its investments to identify and evaluate investments that have an indication of possible impairment. The Company adjusts the carrying value for its privately-held investments 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 years ended December 31, 2015 , the Company determined that no privately-held investments were other-than-temporarily impaired. During the years ended December 31, 2014 , and December 31, 2013 , the Company determined that certain privately-held investments were other-than-temporarily impaired, resulting in impairment charges of $1.1 million and $2.8 million , respectively, that were recorded within other (expense) income, net in the Consolidated Statements of Operations.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis The following tables provide a summary of assets and liabilities measured at fair value on a recurring basis and as reported in the Consolidated Balance Sheets (in millions): Fair Value Measurements at December 31, 2015 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 $ — $ 311.7 $ — $ 311.7 Certificates of deposit — 9.6 — 9.6 Commercial paper — 17.7 — 17.7 Corporate debt securities — 911.4 — 911.4 Foreign government debt securities — 16.5 — 16.5 Government-sponsored enterprise obligations — 203.7 — 203.7 Money market funds (1) 29.7 — — 29.7 Mutual funds (2) 6.2 — — 6.2 Publicly-traded equity securities 8.8 — — 8.8 U.S. government securities 247.3 30.3 — 277.6 Total available-for-sale securities 292.0 1,500.9 — 1,792.9 Trading securities in mutual funds (3) 17.7 — — 17.7 Privately-held debt and redeemable preferred stock securities — — 60.2 60.2 Derivative assets: Foreign exchange contracts — 0.4 — 0.4 Total assets measured at fair value $ 309.7 $ 1,501.3 $ 60.2 $ 1,871.2 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (1.3 ) $ — $ (1.3 ) Total liabilities measured at fair value $ — $ (1.3 ) $ — $ (1.3 ) Total assets measured at fair value, reported as: Cash equivalents $ — $ 3.4 $ — $ 3.4 Restricted investments 35.9 — — 35.9 Short-term investments 108.2 418.9 — 527.1 Long-term investments 165.6 1,078.6 — 1,244.2 Prepaid expenses and other current assets — 0.4 — 0.4 Other long-term assets — — 60.2 60.2 Total assets measured at fair value $ 309.7 $ 1,501.3 $ 60.2 $ 1,871.2 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (1.3 ) $ — $ (1.3 ) Total liabilities measured at fair value $ — $ (1.3 ) $ — $ (1.3 ) ________________________________ (1) Balance includes $29.7 million of restricted investments measured at fair market value, related to the Company's D&O trust and acquisitions related escrows. (2) Balance relates to the restricted investments measured at fair market value of the Company's India Gratuity Trust. (3) Balance relates to the investments measured at fair value related to the Company's non-qualified deferred compensation plan assets. Fair Value Measurements at December 31, 2014 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 $ — $ 269.0 $ — $ 269.0 Certificates of deposit — 10.6 — 10.6 Commercial paper — 20.3 — 20.3 Corporate debt securities — 738.0 — 738.0 Foreign government debt securities — 24.6 — 24.6 Government-sponsored enterprise obligations — 162.1 — 162.1 Money market funds (1) 594.2 — — 594.2 Mutual funds (2) 4.0 — — 4.0 Publicly-traded equity securities 2.0 — — 2.0 U.S. government securities 246.0 — — 246.0 Total available-for-sale securities 846.2 1,224.6 — 2,070.8 Trading securities in mutual funds (3) 16.3 — — 16.3 Privately-held debt and redeemable preferred stock securities — — 47.5 47.5 Derivative assets: Foreign exchange contracts — 0.1 — 0.1 Total assets measured at fair value $ 862.5 $ 1,224.7 $ 47.5 $ 2,134.7 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (3.9 ) $ — $ (3.9 ) Total liabilities measured at fair value $ — $ (3.9 ) $ — $ (3.9 ) Total assets measured at fair value, reported as: Cash equivalents $ 552.9 $ 23.7 $ — $ 576.6 Restricted investments 45.2 — — 45.2 Short-term investments 87.0 245.2 — 332.2 Long-term investments 177.4 955.7 — 1,133.1 Prepaid expenses and other current assets — 0.1 — 0.1 Other long-term assets — — 47.5 47.5 Total assets measured at fair value $ 862.5 $ 1,224.7 $ 47.5 $ 2,134.7 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (3.9 ) $ — $ (3.9 ) Total liabilities measured at fair value $ — $ (3.9 ) $ — $ (3.9 ) _______________________________ (1) Balance includes $41.3 million of restricted investments measured at fair market value, related to the Company's D&O trust and acquisition related escrows. (2) Balance relates to the restricted investments measured at fair market value of the Company's India Gratuity Trust. (3) Balance relates to the investments measured at fair value related to the Company's non-qualified deferred compensation plan assets. 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 years ended December 31, 2015 and December 31, 2014 , 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 absence of quoted market prices and an inherent lack of liquidity. The Company estimates the fair value of its privately-held debt investments on a recurring basis using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. During the year ended December 31, 2015 , there were $5.3 million purchases related to privately-held debt securities. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain of the Company's assets, including intangible assets, goodwill, and privately-held equity investments, are measured at fair value on a nonrecurring basis, only if impairment is indicated. Privately-held equity investments, 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 fair value of investments. The Company estimates the fair value of its privately-held equity investments using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. Purchased intangible assets are measured at fair value primarily using discounted cash flow projections. As of December 31, 2015 and December 31, 2014 , the Company had no significant privately-held equity investments measured at fair value on a nonrecurring basis. As of December 31, 2013 , the Company had $2.0 million of privately-held equity investments measured at fair value on a nonrecurring basis and were classified as Level 3 assets due to the absence of quoted market prices and inherent lack of liquidity. The impairment charges of $2.8 million , representing the difference between the net book value and the fair value, are recorded to other (expense) income, net in the Consolidated Statements of Operations. As of December 31, 2014 , the Company recorded a goodwill impairment charge of $850.0 million for its Security reporting unit measured at fair value on a nonrecurring basis. The remeasurement of goodwill is classified as a Level 3 value assessment due to the significance of unobservable inputs developed using company-specific information. Refer to Note 7, Goodwill and Purchased Intangible Assets , for further information on the goodwill impairment charge and the unobservable inputs used. As of December 31, 2015 , 2014 , and 2013 , 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 December 31, 2015 and December 31, 2014 , the estimated fair value of the Company's short-term and long-term debt in the Consolidated Balance Sheets was approximately $1,946.7 million and $1,395.2 million , respectively, based on observable market inputs (Level 2). As of December 31, 2015 , the carrying value of the promissory note, including interest paid in kind, of $132.9 million in connection with the sale of Junos Pulse recorded in other long-term assets in the Consolidated Balance Sheet approximates its fair value. The promissory note is classified as a Level 3 asset due to the absence of quoted market prices and inherent lack of liquidity. Refer to Note 8, Other Financial Information for further information on the promissory note.

Derivative Instruments

Derivative Instruments	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments The Company uses derivatives to partially offset its market exposure to fluctuations in certain foreign currencies and does not enter into derivatives for speculative or trading purposes. The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions): As of December 31, 2015 2014 Cash flow hedges $ 116.8 $ 160.7 Non-designated derivatives 71.8 78.0 Total $ 188.6 $ 238.7 Cash Flow Hedges The Company uses foreign currency forward or option contracts to hedge the Company's planned cost of services and operating expenses denominated in foreign currencies. These derivatives are designated as cash flow hedges. Execution of these cash flow hedge derivatives typically occurs every month with maturities of one year or less. See Note 5, Fair Value Measurements, for the fair values of the Company’s derivative instruments in the Consolidated Balance Sheets. As of December 31, 2015 , the Company recognized a loss of $6.3 million in accumulated other comprehensive (loss) income for the effective portion of its derivative instruments and reclassified a loss of $9.6 million during the year ended December 31, 2015 from other comprehensive income to operating expense in the Consolidated Statements of Operations. As of December 31, 2014 , the Company recognized a loss of $3.4 million in accumulated other comprehensive (loss) income for the effective portion of its derivative instruments and reclassified a gain of $3.4 million during the year ended December 31, 2014 from other comprehensive (loss) income to operating expense in the Consolidated Statements of Operations. As of December 31, 2013 , the Company recognized a loss of $1.0 million in accumulated other comprehensive income for the effective portion of its derivative instruments and reclassified a gain of $0.7 million during the year ended December 31, 2013 from other comprehensive income to operating expense in the Consolidated Statements of Operations. The ineffective portion of the Company's derivative instruments recognized in its Consolidated Statements of Operations was not material during the years ended December 31, 2015 , 2014 , and 2013 . Non-Designated Derivatives During the years ended December 31, 2015 , 2014 , and 2013 , the Company recognized a net loss of $0.6 million , a net loss of $2.4 million , and a net gain of $0.9 million , respectively, on non-designated derivative instruments within other (expense) income, net, in its Consolidated Statements of Operations. Offsetting of Derivatives The Company presents its derivative assets and derivative liabilities on a gross basis in the Consolidated Balance Sheets. However, under agreements containing provisions on netting with certain counterparties of foreign exchange contracts, subject to applicable requirements, the Company is allowed to net-settle transactions on the same date in the same currency, with a single net amount payable by one party to the other. As of December 31, 2015 and 2014 , respectively, the potential effect of rights of setoff associated with derivative instruments was not material. The Company is neither required to pledge nor entitled to receive cash collateral related to these derivative transactions.

Goodwill and Purchased Intangib

Goodwill and Purchased Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Purchased Intangible Assets	Goodwill and Purchased Intangible Assets Goodwill The following table presents the goodwill activity (in millions): Total December 31, 2013 $ 4,057.7 Additions due to business combination 13.6 Impairment (850.0 ) Divestiture (239.8 ) December 31, 2014 2,981.5 Other (0.2 ) December 31, 2015 $ 2,981.3 In the fourth quarter, the Company performed its annual goodwill impairment test for the Company's three reporting units: Routing, Switching, and Security for the years ended December 31, 2015, 2014, and 2013, respectively. During the year ended December 31, 2015, the Company elected to perform the qualitative assessment for all of the Company's reporting units. This qualitative assessment included the review of certain macroeconomic factors and entity-specific qualitative factors to determine if it was more-likely-than not that the fair values of the Company's reporting units were below carrying value. As a result of the qualitative assessment, the Company concluded that it was more-likely-than-not that goodwill was not impaired. In 2014, the Company determined that the Security reporting unit's carrying value of goodwill exceeded the implied fair value of goodwill, resulting in a goodwill impairment charge of $850.0 million , which was recorded in the Consolidated Statement of Operations. There was no goodwill impairment in 2013. In the fourth quarter of 2014, the Company compared each reporting units’ fair value to their current value to determine whether an impairment exists. The fair value was determined by using a combination of the income approach and the market approach. Under the income approach, the fair value of each reporting unit was based on the present value of the estimated future cash flows that the reporting unit is expected to generate over its remaining life. Cash flow projections were based on management's estimates of revenue growth rates and operating margins, taking into consideration industry and market conditions. The discount rates used were based on the weighted-average cost of capital adjusted for the relevant risk associated with business-specific characteristics and the uncertainty related to the reporting unit’s ability to execute on the projected cash flows. Under the market approach, the Company estimated the fair value based on market multiples of revenue and earnings derived from comparable publicly-traded companies with similar operating and investment characteristics as the reporting units. The income approach and the market approach were equally weighted to derive the fair value of each reporting unit. The fair value of the Company’s Routing and Switching reporting units significantly exceeded their carrying value. However the fair value of the Security reporting unit did not exceed its carrying value and therefore the Company determined the Security reporting unit’s goodwill was impaired. In 2014, the Company re-aligned its go-to-market and research and development ("R&D") resources on projects with the highest potential for growth and continued to leverage its engineering efforts across its Routing, Switching, and Security products. In the fourth quarter of 2014, the Company began to implement a new Security strategy focused on network resiliency and performance based on the SRX platform. As a result, the Company rationalized its Security product portfolio including developing a new product roadmap and exiting certain point products, including the divestiture of Junos Pulse. These factors decreased the Company's short term and near term revenue and profitability forecasts of the Security reporting unit. In determining the impairment amount, the fair value of the Security reporting unit was allocated to its assets and liabilities, including any unrecognized intangible assets, based on their respective fair values. Assumptions used in measuring the value of these assets and liabilities included the discount rates, customer renewal rates, and technology obsolescence rates used in valuing the intangible assets, and pricing of comparable transactions in the market in valuing the tangible assets. Purchased Intangible Assets The Company’s purchased intangible assets were as follows (in millions): Gross Accumulated Amortization Accumulated Impairments and Other Charges Net As of December 31, 2015 Intangible assets with finite lives: Technologies and patents $ 567.7 $ (491.8 ) $ (49.9 ) $ 26.0 Customer contracts, support agreements, and related relationships 78.1 (67.8 ) (2.8 ) 7.5 Other 1.1 (0.7 ) — 0.4 Total purchased intangible assets $ 646.9 $ (560.3 ) $ (52.7 ) $ 33.9 As of December 31, 2014 Intangible assets with finite lives: Technologies and patents $ 567.7 $ (466.1 ) $ (49.9 ) $ 51.7 Customer contracts, support agreements, and related relationships 78.1 (65.2 ) (2.8 ) 10.1 Other 1.1 (0.5 ) — 0.6 Total purchased intangible assets $ 646.9 $ (531.8 ) $ (52.7 ) $ 62.4 The following table presents the amortization of intangible assets included in the Consolidated Statements of Operations (in millions): Years Ended December 31, 2015 2014 2013 Cost of revenues $ 24.6 $ 30.9 $ 27.3 Operating expenses: Sales and marketing 2.8 4.2 3.4 General and administrative 1.1 1.2 1.2 Total operating expenses 3.9 5.4 4.6 Total $ 28.5 $ 36.3 $ 31.9 During the year ended December 31, 2015 , the Company recorded $5.6 million to cost of revenues in the Consolidated Statements of Operations, related to the acceleration of the end-of-life of certain intangible assets. In connection with the restructuring plan in 2014 in Note 9, Restructuring and Other Charges , the Company determined certain intangible assets of $20.0 million were no longer utilized. During the year ended December 31, 2014, the Company recorded charges of $19.3 million in cost of revenues and $0.7 million in restructuring and other charges in the Consolidated Statements of Operations. There were no impairment charges to purchased intangible assets during the year ended December 31, 2013 . As of December 31, 2015 , the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions): Years Ending December 31, Amount 2016 $ 11.6 2017 7.0 2018 5.1 2019 4.9 2020 4.8 Thereafter 0.5 Total $ 33.9

Other Financial Information

Other Financial Information	12 Months Ended
	Dec. 31, 2015
Other Financial Information [Abstract]
Other Financial Information	Other Financial Information Inventories The Company purchases and holds inventory to provide adequate component supplies over the life of the underlying products. The majority of the Company's inventory is production components to be used in the manufacturing process and finished goods inventory in transit. Inventories are reported both within prepaid expenses and other current assets and other long-term assets in the Consolidated Balance Sheets. Total inventories consisted of the following (in millions): As of December 31, 2015 2014 Production materials $ 61.9 $ 38.3 Finished goods 13.1 24.2 Inventories $ 75.0 $ 62.5 In connection with the 2014 Restructuring Plan discussed in Note 9, Restructuring and Other Charges , the Company accelerated the end-of-service life of certain products resulting in inventory charges of $15.5 million , recorded within cost of revenues in the Consolidated Statement of Operations for December 31, 2014 . There were no similar charges recorded during the years ended December 31, 2015 and 2013 . Property and Equipment, Net Property and equipment, net, consisted of the following (in millions): As of December 31, 2015 2014 Computers and equipment $ 915.1 $ 806.1 Software 169.1 161.2 Leasehold improvements 203.4 179.5 Furniture and fixtures 43.2 33.7 Building and building improvements 246.1 238.4 Land and land improvements 241.1 241.0 Construction-in-process (1) 158.2 70.3 Property and equipment, gross 1,976.2 1,730.2 Accumulated depreciation (955.2 ) (825.9 ) Property and equipment, net $ 1,021.0 $ 904.3 _______________________________ (1) On July 10, 2015, the Company entered into a data center lease agreement that was accounted for as a build-to-suit lease. As the Company was deemed to be the owner of the property during the construction period, the Company capitalized the construction cost in property, plant and equipment and recorded a corresponding financing liability of $45.6 million on the Consolidated Balance Sheet as of December 31, 2015. Depreciation expense was $141.5 million , $141.9 million , and $148.2 million in 2015 , 2014 , and 2013 , respectively. Property and equipment is periodically reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Other Long-Term Assets Other long-term assets consisted of the following (in millions): As of December 31, 2015 2014 Privately-held investments $ 102.4 $ 89.9 Licensed software 7.1 8.6 Federal income tax receivable 28.9 20.0 Customer financing receivable — 16.9 Inventory 8.4 8.0 Prepaid costs, deposits, and other (1) 110.5 75.1 Promissory note, including principal and accrued interest, in connection with the sale of Junos Pulse 132.9 125.0 Other long-term assets (1) $ 390.2 $ 343.5 _______________________________ (1) During the year ended December 31, 2015, the Company early adopted ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the Consolidated Balance Sheets. Certain amounts in the prior-year Consolidated Financial Statements were retrospectively adjusted to conform to the current-year presentation. 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 (the “Pulse Note”). On October 2, 2015, the Company and the issuer of the Pulse Note mutually agreed to amend the original terms of the Pulse Note. Under the terms of the modified Pulse Note, the parties agreed to extend the maturity date from April 1, 2016 to December 31, 2018, provided 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, increase the interest payable on the Pulse Note, and include semi-annual excess cash flow sweeps commencing in 2016, and required certain other debt to be subordinated to the promissory note issued to the Company. 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 amount previously pre-paid to the Company, and use commercially reasonable efforts to refinance the entire note, with any remaining balance due by December 31, 2018. In connection with the amendment, certain holding companies of the issuer also provided the Company with a guarantee and additional collateral to secure the repayment of the amended promissory note. The note receivable, along with the related interest receivable, are classified as long-term assets based on expected collection beyond twelve months from the 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 December 31, 2015. 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 years ended December 31, 2015 and December 31, 2014 , the related amount of interest income recognized was $6.3 million and $1.6 million , respectively. Warranties The Company accrues for warranty costs based on associated material, labor for customer support, and overhead at the time revenue is recognized. This accrual is reported within other accrued liabilities in the Consolidated Balance Sheets. Changes in the Company’s warranty reserve were as follows (in millions): As of December 31, 2015 2014 Beginning balance $ 28.7 $ 28.0 Provisions made during the period, net 27.9 28.6 Actual costs incurred during the period (28.2 ) (27.9 ) Ending balance $ 28.4 $ 28.7 Deferred Revenue Details of the Company's deferred revenue, as reported in the Consolidated Balance Sheets, were as follows (in millions): As of December 31, 2015 2014 Deferred product revenue: Undelivered product commitments and other product deferrals $ 210.1 $ 180.3 Distributor inventory and other sell-through items 81.8 103.7 Deferred gross product revenue 291.9 284.0 Deferred cost of product revenue (51.6 ) (58.4 ) Deferred product revenue, net 240.3 225.6 Deferred service revenue 927.8 850.1 Total $ 1,168.1 $ 1,075.7 Reported as: Current $ 822.9 $ 780.8 Long-term 345.2 294.9 Total $ 1,168.1 $ 1,075.7 Deferred product revenue represents unrecognized revenue related to shipments to distributors that have not sold through to end-users, undelivered product commitments, and other shipments that have not met all revenue recognition criteria. In circumstances when costs are deferred, deferred product revenue is recorded net of the related costs of product revenue. Deferred service revenue represents billable amounts for service contracts, which include technical support, hardware and software maintenance, professional services, and training, for which services have not been rendered. Other (Expense) Income, Net Other (expense) income, net consisted of the following (in millions): Years Ended December 31, 2015 2014 2013 Interest income $ 21.8 $ 10.0 $ 8.7 Interest expense (83.3 ) (66.9 ) (58.4 ) Net gain on legal settlement — 196.1 — Gain on investments 6.8 167.9 11.3 Gain on sale of Junos Pulse — 19.6 — Other (5.1 ) 6.7 (2.0 ) Other (expense) income, net $ (59.8 ) $ 333.4 $ (40.4 ) Interest income primarily includes interest earned on the Company’s cash, cash equivalents, investments, and on the promissory note issued to the Company in connection with the sale of Junos Pulse. Interest expense primarily includes interest, net of capitalized interest expense, from short-term debt, long-term debt, and customer financing arrangements. Other typically consists of investment and foreign exchange gains and losses and other non-operational income and expense items. Interest Expense For the years ended December 31, 2015 , 2014 and 2013 , interest expense included $79.8 million , net of $2.2 million capitalized, $57.5 million , net of $2.7 million capitalized, and $45.2 million , net of $1.9 million capitalized, respectively, related to the Company's outstanding short-term and long-term debt issued in March 2011, March 2014, and March 2015 discussed in Note 10, Debt and Financing . Gain on Legal Settlement During the year ended December 31, 2014, the Company entered into a settlement agreement with Palo Alto Networks, Inc., or Palo Alto Networks, resolving a patent litigation between the two companies, which resulted in a realized gain on legal settlement and subsequent sale of related securities of $196.1 million , net of legal fees. Gain on Investments During the years ended December 31, 2015 and December 31, 2013, the Company recorded a gain of $6.8 million and $7.1 million , respectively, primarily related to the sale of its privately-held investments. During the year ended December 31, 2014 , the Company recorded a gain of $163.0 million primarily related to the sale of investments which were converted from privately-held investments to publicly-traded equity upon initial public offering and subsequently sold. Gain on Sale of Junos Pulse 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 issued to the Company. As a result of the sale, the Company recorded a gain of $19.6 million in other (expense) income, net in the Consolidated Statement of Operations. The Company's sale of Junos Pulse was driven by product rationalization in connection with the Company's initiative to focus on projects with the highest potential for growth.

Restructuring and Other Charges

Restructuring and Other Charges	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Other Charges	Restructuring and Other Charges In the first quarter of 2014, the Company initiated a restructuring plan (the “2014 Restructuring Plan”) designed to refocus the Company's strategy, optimize its structure, and improve operational efficiencies. The 2014 Restructuring Plan consisted of workforce reductions, facility consolidations and closures, asset write-downs, contract terminations and other charges. The Company had also initiated restructuring plans in each of the fiscal years from 2011 through 2013, each of which focused on improving the Company's cost structure through product portfolio rationalizations, workforce reductions, contract terminations, project cancellations, and facility closures and consolidations. As of December 31, 2014, the Company's restructuring plans had been substantially completed and the Company does not expect to record significant future charges under any of these restructuring plans. Restructuring and other charges and (benefits) The following table presents restructuring and other charges and (benefits) included in cost of revenues and restructuring and other (benefits) charges in the Consolidated Statements of Operations under the Company's restructuring plans (in millions): Years Ended December 31, 2015 2014 2013 Severance $ 0.4 $ 52.6 $ 22.9 Facilities (1.0 ) 14.4 10.0 Contract terminations and other — 2.3 14.6 Asset impairments and write-downs (3.5 ) 139.2 — Total $ (4.1 ) $ 208.5 $ 47.5 Reported as: Cost of revenues $ (3.5 ) $ 41.5 $ 8.4 Restructuring and other (benefits) charges (0.6 ) 167.0 39.1 Total $ (4.1 ) $ 208.5 $ 47.5 2014 Restructuring Plan During the year ended December 31, 2015, the Company recorded a benefit of $3.5 million for a previously recorded charge related to certain products with contract manufacturers for acceleration of the end-of-service life of such products to cost of revenues in the Consolidated Statements of Operations. Additionally, the Company recorded $0.4 million of severance costs and a benefit of $1.0 million for facilities that were recorded in restructuring and other (benefits) charges in the Consolidated Statements of Operations, in connection with the 2014 Restructuring Plan. During the year ended December 31, 2014, the Company recorded $52.0 million of severance costs, $14.2 million of facility consolidation and closures costs, $85.4 million of impairment charges related to licensed software, $12.3 million of asset write-downs, and $2.3 million of charges related to contract terminations, which were recorded to restructuring and other charges in the Consolidated Statements of Operations. In connection with the facility consolidation and closures charge of $14.2 million , the Company, with the consent of its landlord and the administrative agent for the holder of certain liens secured upon the buildings on the leased premises, assigned certain of its real property leases, totaling approximately 0.4 million square feet, to a third party. Concurrently with the assignments, the Company executed a sublease with the assignee for one of the properties of approximately 0.1 million square feet, for a period of two years , with one -time right to extend the term for up to six months . Under these arrangements, the Company paid $12.3 million to the landlord and was released from all future lease obligations following the date of the assignments. The Company also incurred $5.3 million of transaction fees, which were recorded to restructuring and other charges in the Consolidated Statements of Operations. Offsetting these charges was an adjustment relating to deferred rent liability relating to these premises of $9.8 million . The Company also recorded inventory write-downs of $15.5 million , intangibles write-downs of $19.3 million , and a charge related to products with contract manufacturers of $6.7 million for acceleration of the end-of-service life of certain products to cost of revenues in the Consolidated Statements of Operations during the year ended December 31, 2014. 2013 Restructuring Plan During 2013, the Company initiated a restructuring plan (the "2013 Restructuring Plan") to continue to improve its cost structure and rationalize its product portfolio and rebalance its investments. The 2013 Restructuring Plan consists of workforce reductions, contract terminations, and project cancellations. The Company recorded $0.6 million in severance costs related to the 2013 Restructuring Plan during the year ended December 31, 2014. Under the 2013 Restructuring Plan, total costs incurred through December 31, 2014 were $28.9 million , of which $3.3 million was recorded within cost of revenues and $25.6 million was recorded within restructuring and other charges in the Consolidated Statements of Operations. The restructuring activities related to this plan are substantially complete, and the Company does not expect to record significant future charges under this plan. Restructuring Liability Restructuring liabilities are reported within other accrued liabilities and other long-term liabilities in the Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liability related to the Company's plans during the year ended December 31, 2015 (in millions): December 31, Charges Cash Payments Non-cash Settlements and Other December 31, Severance $ 9.4 $ 0.4 $ (8.2 ) $ (1.6 ) $ — Facilities 7.4 (1.0 ) (2.3 ) (1.3 ) 2.8 Contract terminations and other 0.2 (3.5 ) — 3.3 — Total $ 17.0 $ (4.1 ) $ (10.5 ) $ 0.4 $ 2.8 As of December 31, 2015 , the Company's restructuring liability was $2.8 million related to facility closures, which are expected to be paid through March 2018.

Debt and Financing

Debt and Financing	12 Months Ended
	Dec. 31, 2015
Debt Instruments [Abstract]
Debt and Financing	Debt and Financing Debt The following table summarizes the Company's short-term and long-term debt (in millions, except percentages): As of December 31, 2015 Amount Effective Interest Rates Senior notes: 3.10% fixed-rate notes, due March 2016 $ 300.0 3.25 % 3.30% fixed-rate notes, due June 2020 300.0 3.47 % 4.60% fixed-rate notes, due March 2021 300.0 4.69 % 4.50% fixed-rate notes, due March 2024 350.0 4.63 % 4.35% fixed-rate notes, due June 2025 300.0 4.47 % 5.95% fixed-rate notes, due March 2041 400.0 6.03 % Total senior notes 1,950.0 Unaccreted discount (1.3 ) Total $ 1,948.7 Reported as: Short-term debt $ 299.9 Long-term debt 1,648.8 Total $ 1,948.7 In March 2015, the Company issued $300.0 million aggregate principal amount of 3.30% senior notes due 2020 ("2020 Notes") and $300.0 million aggregate principal amount of 4.35% senior notes due 2025 ("2025 Notes"). In March 2014, the Company issued $350.0 million aggregate principal amount of 4.50% senior notes due 2024 ("2024 Notes"). In March 2011, the Company issued $300.0 million aggregate principal amount of 3.10% senior notes due 2016 ("2016 Notes"), $300.0 million aggregate principal amount of 4.60% senior notes due 2021 ("2021 Notes"), and $400.0 million aggregate principal amount of 5.95% senior notes due 2041 ("2041 Notes"). The "2016 Notes," "2020 Notes," "2021 Notes," "2024 Notes," "2025 Notes" and "2041 Notes" collectively the "Notes" 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. The Company may redeem the 2020 Notes and 2025 Notes, either in whole or in part, at any time one month prior to the maturity date of the 2020 Notes, and three months prior to the maturity date of the 2025 Notes, at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the 2020 Notes and 2025 Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted at the Treasury rate plus 30 basis points for the 2020 Notes, or the Treasury rate plus 37.5 basis points for the 2025 Notes, plus, in the case of each of the clauses (i) and (ii) above, accrued and unpaid interest, if any. At any time on or after May 15, 2020, in the case of the 2020 Notes, and at any time on or after March 15, 2025, in the case of the 2025 Notes, the Company may redeem Notes of such series, in whole or in part, at a redemption price equal to 100% of the principal amount of the 2020 Notes and the 2025 Notes to be redeemed, plus accrued and unpaid interest, if any. The Company may redeem the other Notes, either in whole or in part, at any time at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted to the redemption date, plus, in either case, accrued and unpaid interest, if any. In the event of a change of control repurchase event, the holders of the Notes may require the Company to repurchase for cash all or part of the Notes at a purchase price equal to 101% of the aggregate principal amount, plus accrued and unpaid interest, if any. Interest on the Notes is payable in cash semiannually. The effective interest rates for the Notes include the interest on the Notes, accretion of the discount, and amortization of issuance costs. The indentures that govern the Notes also contain various covenants, including limitations on the Company's ability to incur liens or enter into sale-leaseback transactions over certain dollar thresholds. As of December 31, 2015 , 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 and Citibank, N.A., as administrative agent, that provides for a $500.0 million unsecured revolving credit facility, with an option of the Company to increase the amount of the credit facility by up to an additional $200.0 million , subject to certain conditions. Proceeds of loans made under the Credit Agreement may be used by the Company for working capital and general corporate purposes. Revolving loans may be borrowed, repaid and reborrowed until June 27, 2019, at which time all amounts borrowed must be repaid. Borrowing may be denominated, at the Company's option in U.S. dollars, Pounds Sterling or Euro. 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. Base rate is defined as the greatest of (A) Citibank's base rate , (B) the Federal Funds rate plus 0.50% or (C) the ICE Benchmark Administration Settlement Rate applicable to dollars for a period of one month plus 1.00% . The Eurocurrency rate is determined for U.S. dollars and Pounds Sterling as the rate at which deposits in such currency are offered in the London interbank market for the applicable interest period and for Euro as the rate specified for deposits in Euro with a maturity comparable to the applicable interest period. As of December 31, 2015 , the Company was in compliance with all covenants in the Credit Agreement, and no amounts were outstanding. Customer Financing Arrangements The Company provides certain distribution partners access to extended financing arrangements for certain end-user customers that require longer payment terms than those typically provided by the Company through 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. Beginning in 2014 and through 2015, the Company transitioned certain distribution partners from the third party financing program to the Company's commercial payment terms. As a result, the Company's customer financing activities significantly declined from fiscal year 2014 to fiscal year 2015. Pursuant to the financing arrangements for the sale of receivables, the Company sold net receivables of $72.5 million , $440.3 million and $898.4 million during the years ended December 31, 2015 , 2014 , and 2013 , respectively. The Company received cash proceeds from the financing provider of $99.3 million , $602.1 million , and $843.9 million during the years ended December 31, 2015 , 2014 , and 2013 , respectively. As of December 31, 2015 and December 31, 2014 , the amounts owed by the financing provider were $1.2 million and $28.0 million , respectively, and were recorded in accounts receivable on the Company’s Consolidated Balance Sheets. The Company has provided guarantees to third-party financing companies for certain third-party financing arrangements extended to certain end-user customers, which have terms of up to three years. The Company is liable for the aggregate unpaid payments to the third-party financing company in the event of customer default. As of December 31, 2015 , the Company has not been required to make any payments under these arrangements. Pursuant to these arrangements, the Company has guarantees for third-party financing arrangements of $9.9 million as of December 31, 2015 . The portion of the receivable financed that has not been recognized as revenue is accounted for as a financing arrangement and is included in other accrued liabilities and other long-term liabilities in the Consolidated Balance Sheets . As of December 31, 2015 and 2014 , the cash received from the financing provider not recognized as revenue was $1.4 million and $45.3 million , respectively.

Equity

Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Equity	Equity Cash Dividends on Shares of Common Stock During 2015 , the Company declared four quarterly cash dividends of $0.10 per share on its common stock on January 27, 2015, April 23, 2015, July 23, 2015 and on October 22, 2015, which were paid on March 24, 2015, June 23, 2015, September 22, 2015 and on December 22, 2015, respectively, to stockholders of record as of the close of business on March 3, 2015, June 2, 2015, September 1, 2015, and December 1, 2015, respectively, in the aggregate amount of $156.3 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 18, Subsequent Events, for discussion of the Company's dividend declaration subsequent to December 31, 2015 . Stock Repurchase Activities In February 2014, the Company's 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 ("2014 Stock Repurchase Program"). In October 2014 and July 2015, the Board authorized a $1.3 billion and $500.0 million increase, respectively, to the 2014 Stock Repurchase Program for a total of $3.9 billion . As of December 31, 2015, there was $532.5 million of authorized funds remaining under the 2014 Stock Repurchase Program. In addition to repurchases under the Company’s 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. The following table summarizes the Company's repurchases and retirements of its common stock under its stock repurchase programs and accelerated share repurchase, and repurchases associated with minimum tax withholdings (in millions, except per share amounts): Shares Repurchased Average price per share Amount Repurchased 2015 Repurchases under stock repurchase program 45.4 $ 25.16 $ 1,142.5 Repurchases for tax withholding 0.4 $ 26.70 $ 11.1 2014 Repurchases under stock repurchase program 46.8 $ 22.42 $ 1,050.0 Accelerated share repurchase (1) 49.3 $ 24.35 $ 1,200.0 Repurchases for tax withholding 0.6 $ 19.69 $ 12.5 2013 Repurchases under stock repurchase program 28.9 $ 19.76 $ 570.6 Repurchases for tax withholding 0.4 $ 20.23 $ 7.2 _______________________________ (1) As part of the 2014 Stock Repurchase Program, the Company entered into two separate accelerated share repurchase agreements (collectively, the "ASR") with two financial institutions to repurchase $1.2 billion of the Company's common stock. The Company made an up-front payment of $1.2 billion pursuant to the ASR to repurchase the Company's common stock. The aggregate number of shares ultimately purchased was determined based on a volume weighted average repurchase price, less an agreed upon discount. The shares received with respect to the ASR have been retired. Retired shares return to authorized but unissued shares of common stock. Future share repurchases under the Company’s stock repurchase programs will be subject to a review of the circumstances at that time and will be made from time to time in private transactions or open market purchases as permitted by securities laws and other legal requirements. The Company's stock repurchase programs may be discontinued at any time. See Note 18, Subsequent Events, for discussion of the Company's stock repurchase activity subsequent to December 31, 2015 . Accumulated Other Comprehensive Loss, Net of Tax The components of accumulated other comprehensive loss, net of related taxes, for the years ended December 31, 2015 and December 31, 2014 were as follows (in millions): Unrealized Gains (Losses) on Available-for- Sale Securities (1) Unrealized Gains (Losses) on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2013 $ 66.2 $ 2.2 $ (3.8 ) $ 64.6 Other comprehensive gain (loss) before reclassifications 48.7 (4.1 ) (14.2 ) 30.4 Amount reclassified from accumulated other comprehensive income (106.5 ) (2.3 ) — (108.8 ) Other comprehensive loss (57.8 ) (6.4 ) (14.2 ) (78.4 ) Balance as of December 31, 2014 $ 8.4 $ (4.2 ) $ (18.0 ) $ (13.8 ) Other comprehensive gain (loss) before reclassifications 9.1 (6.7 ) (16.9 ) (14.5 ) Amount reclassified from accumulated other comprehensive income (0.5 ) 9.6 — 9.1 Other comprehensive gain (loss), net 8.6 2.9 (16.9 ) (5.4 ) Balance as of December 31, 2015 $ 17.0 $ (1.3 ) $ (34.9 ) $ (19.2 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive income, net of tax during the years ended December 31, 2015 and December 31, 2014 for realized gains on available-for-sale securities of $0.5 million and $104.3 million , respectively, are included in other (expense) income, net, in the Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive (loss) income, net of tax during the year ended December 31, 2015 for realized losses on cash flow hedges are included within cost of revenues of $2.9 million , research and development of $0.2 million , sales and marketing of $6.0 million , and general and administrative of $0.5 million in the Consolidated Statements of Operations. The reclassifications out of accumulated other comprehensive income during the year ended December 31, 2014 for realized gains on cash flow hedges are included within research and development of $1.4 million , sales and marketing of $0.3 million , and general and administrative of $0.7 million and for realized losses within cost of revenues of $0.1 million for which the hedged transactions relate in the Consolidated Statements of Operations.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefit Plans	Employee Benefit Plans Equity Incentive Plans The Company’s equity incentive plans include the 2015 Equity Incentive Plan (the “2015 Plan”), the 2006 Equity Incentive Plan (the “2006 Plan”), the Amended and Restated 1996 Stock Plan (the “1996 Plan”), various equity incentive plans assumed through acquisitions, and the ESPP. Under these plans, the Company has granted (or, in the case of acquired plans, assumed) stock options, restricted stock units (“RSUs”), restricted stock awards (“RSAs”), and performance share awards (“PSAs”). The 2015 Plan was adopted and approved by the Company's stockholders in May 2015 and had an initial authorized share reserve of 38.0 million shares of common stock plus the addition of any shares subject to outstanding awards under the 2006 Plan and the 1996 Plan that were outstanding as of May 19, 2015, and that subsequently expire or otherwise terminate, up to a maximum of an additional 29.0 million shares. As of December 31, 2015 , an aggregate of 20.5 million shares were subject to outstanding equity awards under the 2015 Plan, the 2006 Plan, and the 1996 Plan. As of December 31, 2015 , 36.7 million shares were available for future issuance under the 2015 Plan and no shares were available for future issuance under the 2006 Plan or the 1996 Plan. As of December 31, 2015 , a total of approximately 66.5 million shares of common stock were reserved for future issuance upon exercise of stock options and vesting of RSUs, RSAs, and PSAs, and for the future grant of share-based compensation awards under the Company's equity incentive plans. The ESPP was adopted and approved by the Company's stockholders in May 2008. To date, the Company's stockholders have approved a share reserve of 26.0 million shares of the Company's common stock for issuance under the ESPP, which includes an additional 7.0 million shares approved by the Company's stockholders in May 2015. The ESPP permits eligible employees to acquire shares of the Company’s common stock at a 15% discount to the offering price (as determined in the ESPP) through periodic payroll deductions of up to 10% of base compensation, subject to individual purchase limits of 6,000 shares in any twelve -month period or $25,000 worth of stock, determined at the fair market value of the shares at the time the stock purchase option is granted, in one calendar year. As of December 31, 2015 , approximately 18.4 million shares have been issued and 7.6 million shares remain available for future issuance under the ESPP. During 2014, the Company completed the acquisition of WANDL Inc. and assumed the WANDL Inc. 2013 Restricted Stock Unit Plan. In connection with this plan, the Company assumed RSUs, RSAs, and PSAs and exchanged the assumed awards for Juniper Networks' RSUs, RSAs, and PSAs, respectively. The Company assumed an aggregate of 1.5 million shares of RSUs, RSAs, and PSAs in connection with the acquisition of WANDL Inc. No additional awards can be granted under this plan. As of December 31, 2015 , stock options, RSUs, RSAs, and PSAs representing approximately 1.7 million shares of common stock were outstanding under all awards assumed through the Company's acquisitions. Stock Option Activities Since 2006, the Company has granted stock option awards that have a maximum contractual life of seven years from the date of grant. Prior to 2006, stock option awards generally had a ten -year contractual life from the date of grant. The following table summarizes the Company’s stock option activity and related information as of and for the three years ended December 31, 2015 (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, 2012 34.1 $ 24.13 3.1 $ 52.5 Canceled (1.3 ) 29.56 Exercised (5.6 ) 15.58 Expired (4.1 ) 28.35 Balance as of December 31, 2013 23.1 $ 25.15 2.4 $ 44.6 Canceled (0.6 ) 30.15 Exercised (5.4 ) 19.76 Expired (7.2 ) 29.11 Balance as of December 31, 2014 9.9 $ 24.87 2.0 $ 24.7 Canceled (0.1 ) 23.65 Exercised (3.5 ) 19.78 Expired (2.7 ) 27.99 Balance as of December 31, 2015 3.6 $ 27.52 2.1 $ 16.6 As of December 31, 2015: Vested and expected-to-vest options 3.6 $ 27.58 2.1 $ 16.3 Exercisable options 3.4 $ 28.82 1.8 $ 12.1 The aggregate intrinsic value represents the difference between the Company’s closing stock price on the last trading day of the period, which was $27.60 per share as of December 31, 2015 and the exercise price of the applicable options multiplied by the number of related options. The pre-tax intrinsic value of options exercised, representing the difference between the fair market value of the Company’s common stock on the date of the exercise and the exercise price of each option, was $27.5 million , $33.4 million , and $29.4 million for 2015 , 2014 , and 2013 , respectively. Total fair value of options vested during 2015 , 2014 , and 2013 was $7.0 million , $20.8 million , and $45.2 million , respectively. The following table summarizes additional information regarding outstanding and exercisable options as of December 31, 2015 : Options Outstanding Options Exercisable Range of Exercise Price (In dollars) Number Outstanding (In millions) Weighted Average Remaining Contractual Life (In years) Weighted Average Exercise Price (In dollars) Number Exercisable (In millions) Weighted Average Exercise Price (In dollars) $0.03 - $14.68 0.4 5.3 $ 3.38 0.3 $ 4.94 $15.09 - $18.45 0.4 0.7 15.58 0.3 15.47 $18.49 - $26.10 0.4 2.3 24.11 0.3 24.19 $26.39 - $27.44 0.5 1.0 26.97 0.5 26.97 $27.62 - $29.33 0.1 2.0 28.88 0.1 28.88 $29.89 - $29.89 0.5 1.2 29.89 0.5 29.89 $30.01 - $36.49 0.4 1.9 32.76 0.4 32.76 $38.93 - $38.93 0.1 2.4 38.93 0.1 38.93 $40.26 - $40.26 0.5 2.2 40.26 0.6 40.26 $44.00 - $44.00 0.3 2.1 44.00 0.3 44.00 $0.03 - $44.00 3.6 2.1 $ 27.52 3.4 $ 28.82 Restricted Stock Unit, Restricted Stock Award, and Performance Share Award Activities RSUs and RSAs generally vest over a period of three to four years from the date of grant and PSAs generally vest over a period of two to three years provided that certain annual performance targets and other vesting criteria are met. Until vested, RSUs and PSAs do not have the voting and dividend participation rights of common stock and the shares underlying the awards are not considered issued and outstanding. The following table summarizes the Company’s RSU, RSA, and PSA activity and related information as of and for the three years ended December 31, 2015 (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, 2012 26.8 $ 27.76 1.7 $ 565.0 RSUs granted 10.3 20.32 PSAs granted (1) 2.2 21.27 RSUs vested (2) (6.1 ) 26.15 PSAs vested (2) (1.1 ) 28.52 RSAs vested (2) (1.6 ) 19.59 RSUs canceled (3.4 ) 22.99 PSAs canceled (1.7 ) 29.10 Balance as of December 31, 2013 25.4 $ 23.44 1.1 $ 573.5 RSUs granted (3)(6) 10.0 22.52 RSUs assumed (4) 0.4 22.66 RSAs assumed (4) 0.9 22.66 PSAs granted (5)(6) 1.4 24.25 PSAs assumed (4) 0.2 22.66 RSUs vested (2) (7.3 ) 22.98 RSAs vested (2) (1.4 ) 19.59 PSAs vested (2) (1.1 ) 36.19 RSUs canceled (4.0 ) 21.63 PSAs canceled (3.2 ) 30.43 Balance as of December 31, 2014 21.3 $ 22.05 1.1 $ 475.0 RSUs granted (3)(6) 8.9 23.41 PSAs granted (6)(7) 1.0 23.76 RSUs vested (2) (7.2 ) 22.58 RSAs vested (2) (1.8 ) 20.13 PSAs vested (2) (0.3 ) 22.52 RSUs canceled (2.3 ) 22.18 PSAs canceled (1.0 ) 22.27 Balance at December 31, 2015 18.6 $ 22.71 1.1 $ 514.1 As of December 31, 2015 Vested and expected-to-vest RSUs, RSAs, and PSAs 15.3 $ 22.59 1.0 $ 421.3 ________________________________ (1) 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 (or an authorized subcommittee) are achieved at target is 1.1 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 2.2 million shares. (2) Total fair value of RSUs, RSAs, and PSAs vested during 2015 , 2014 , and 2013 was $202.7 million , $238.5 million , and $221.5 million , respectively. (3) Includes service-based and market-based RSUs granted under the 2006 Plan and 2015 Plan according to their terms. (4) RSUs, RSAs, and PSAs assumed in connection with the acquisition of WANDL Inc. (5) 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 (or an authorized subcommittee) are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 1.4 million shares. (6) On February 20, 2014, the Company announced its intention to initiate a quarterly cash dividend of $0.10 per share of common stock in the third quarter of 2014. As a result of the Company's announcement, the grant date fair value of RSUs and PSAs granted after the announcement date were reduced by the present value of the dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested. (7) 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 (or an authorized subcommittee) are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 1.0 million shares. Shares Available for Grant The following table presents the stock activity and the total number of shares available for grant under the 2015 Plan and the 2006 Plan, as applicable: Number of Shares Balance as of December 31, 2014 47.8 RSUs and PSAs granted (1) (20.7 ) RSUs and PSAs canceled (1)(2) 7.0 Options canceled (2) 0.1 Options expired (2) 2.7 Shares discontinued (3) (38.2 ) Shares authorized under the 2015 Plan 38.0 Balance as of December 31, 2015 36.7 ________________________________ (1) RSUs and PSAs with a per share or unit purchase price lower than 100% of the fair market value of the Company's common stock on the day of the grant under the 2015 Plan and the 2006 Plan are counted against shares authorized under the plan as two and one-tenth shares of common stock for each share subject to such award. The number of shares subject to PSAs granted represents the maximum number of shares that may be issued pursuant to the award over its full term. (2) Canceled or expired options under the 2006 Plan and the 1996 Plan and canceled RSUs and PSAs under the 2006 Plan are no longer available for future grant under such plans; however, the number of shares available for grant under the 2015 Plan will be increased by the amount of such canceled or expired options, RSUs or PSAs, as applicable, up to a maximum of 29.0 million additional shares of common stock, pursuant to the terms of the 2015 Plan. (3) Authorized shares not subject to outstanding awards under the 2006 Plan were canceled on May 19, 2015, following the approval by the Company’s stockholders of the 2015 Plan. Effective May 19, 2015, no additional awards are issuable under the 2006 Plan. Employee Stock Purchase Plan The Company's ESPP is implemented in a series of offering periods, each six months in duration, or a shorter period as determined by the Board. Employees purchased approximately 2.7 million , 2.9 million , and 3.3 million shares of common stock through the ESPP at an average exercise price of $19.25 , $19.30 , and $16.53 per share during 2015 , 2014 , and 2013 , respectively. Valuation Assumptions The weighted-average assumptions used and the resulting estimates of fair value for stock options, ESPP, and market-based RSUs were as follows: Years Ended December 31, 2015 2014 2013 ESPP (1) : Volatility 29% 30% 36% Risk-free interest rate 0.1% 0.1% 0.1% Expected life (years) 0.5 0.5 0.5 Dividend yield 1.7% 0% - 1.8% — Weighted-average fair value per share $5.63 $5.72 $5.54 Market-based RSUs (2) Volatility 34% 36% — Risk-free interest rate 1.4% 1.6% — Dividend yield 1.8% 0% - 2.0% — Weighted-average fair value per share $14.97 $16.89 — ________________________________ (1) The Black-Scholes-Merton option-pricing model is utilized to estimate the fair value of ESPP. (2) The fair value of market-based RSUs utilizes the Monte Carlo simulation option pricing model. The Company amortizes the fair value of these awards over the derived service period adjusted for estimated forfeitures for each separately vesting tranche of the award. Provided that the derived service is rendered, the total fair value of the market-based RSUs at the date of grant is recognized as compensation expense even if the market condition is not achieved. However, the number of shares that ultimately vest can vary significantly with the performance of the specified market criteria. Share-Based Compensation Expense Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Company's Consolidated Statements of Operations (in millions): Years Ended December 31, 2015 2014 2013 Cost of revenues - Product $ 5.6 $ 5.0 $ 4.7 Cost of revenues - Service 13.8 14.2 15.4 Research and development 125.4 134.5 127.6 Sales and marketing 45.6 60.2 70.9 General and administrative 26.9 26.1 26.0 Total $ 217.3 $ 240.0 $ 244.6 The following table summarizes share-based compensation expense by award type (in millions): Years Ended December 31, 2015 2014 2013 Stock options $ 6.6 $ 14.9 $ 31.5 RSUs, RSAs, and PSAs 197.3 209.7 196.8 ESPP 13.4 15.4 16.3 Total $ 217.3 $ 240.0 $ 244.6 The following table presents unrecognized compensation cost, adjusted for estimated forfeitures, recognized over a weighted-average period related to unvested stock options, RSUs, RSAs, and PSAs as of December 31, 2015 (in millions, except years): Unrecognized Weighted Average Stock options $ 2.1 0.6 RSUs, RSAs, and PSAs $ 211.2 1.7 401(k) Plan The Company maintains a savings and retirement plan qualified under Section 401(k) of the Internal Revenue Code of 1986, as amended (the "IRC"). Employees meeting the eligibility requirements, as defined under the IRC, may contribute up to the statutory limits each year. The Company currently matches 30% of all eligible employee contributions which vest immediately. The Company’s matching contributions to the plan totaled $19.6 million , $20.2 million , and $20.7 million during the years ended December 31, 2015 , 2014 , and 2013 , respectively. Deferred Compensation Plan The Company’s non-qualified deferred compensation (“NQDC”) plan is an unfunded and unsecured deferred compensation arrangement. Under the NQDC plan, officers and other senior employees may elect to defer a portion of their compensation and contribute such amounts to one or more investment funds. The NQDC plan assets are included within short-term investments and offsetting obligations are included within accrued compensation in the Consolidated Balance Sheets. The investments are considered trading securities and are reported at fair value. The realized and unrealized holding gains and losses related to these investments are recorded in other (expense) income, net, and the offsetting compensation expense is recorded as operating expenses in the Consolidated Statements of Operations. The deferred compensation liability under the NQDC plan was approximately $17.7 million and $16.3 million as of December 31, 2015 and December 31, 2014 , respectively.

Segments

Segments	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segments	Segments The Company conducts business globally and is managed, operated and organized by major functional departments that operate on a consolidated basis. Each major functional leader reports directly to the Company's chief executive officer, who is the chief operating decision maker (“CODM”). The Company’s CODM views the business, allocates resources and assesses the performance of the Company primarily based on consolidated financial information for the entire business, accompanied by disaggregated information about net revenues by product and service and geographic region as presented below. As a result, the Company operates in one reportable operating segment, and all financial segment information can be found in the accompanying Consolidated Financial Statements. The following table presents net revenues by product and service (in millions): Years Ended December 31, 2015 2014 2013 Routing $ 2,359.2 $ 2,223.9 $ 2,318.0 Switching 768.3 721.2 638.0 Security 435.6 463.6 563.9 Total product 3,563.1 3,408.7 3,519.9 Total service 1,294.7 1,218.4 1,149.2 Total $ 4,857.8 $ 4,627.1 $ 4,669.1 The Company attributes revenues to geographic region based on the customer’s ship-to location. The following table presents net revenues by geographic region (in millions): Years Ended December 31, 2015 2014 2013 Americas: United States $ 2,568.6 $ 2,410.6 $ 2,381.5 Other 223.6 219.7 232.0 Total Americas 2,792.2 2,630.3 2,613.5 Europe, Middle East, and Africa 1,320.3 1,263.3 1,256.9 Asia Pacific 745.3 733.5 798.7 Total $ 4,857.8 $ 4,627.1 $ 4,669.1 During the years ended December 31, 2015 , 2014 , and 2013 , no customer accounted for greater than 10% of the Company's net revenues. The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions): As of December 31, 2015 2014 United States $ 925.5 $ 871.7 International 129.4 95.0 Property and equipment, net and purchased intangible assets, net $ 1,054.9 $ 966.7 The Company tracks assets by physical location. The majority of the Company’s assets, excluding cash and cash equivalents and investments, as of December 31, 2015 and December 31, 2014 , were attributable to U.S. operations.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of pretax (loss) income and noncontrolling interest are summarized as follows (in millions): Years Ended December 31, 2015 2014 2013 Domestic $ 456.3 $ (509.7 ) $ 248.7 Foreign 395.9 423.4 276.8 Total pretax (loss) income $ 852.2 $ (86.3 ) $ 525.5 The provision for income taxes is summarized as follows (in millions): Years Ended December 31, 2015 2014 2013 Current provision (benefit): Federal $ 181.4 $ 180.1 $ (12.9 ) States 15.9 15.2 (5.0 ) Foreign 43.3 33.7 32.5 Total current provision (benefit) 240.6 229.0 14.6 Deferred provision (benefit): Federal (16.7 ) 17.3 51.2 States (0.4 ) 1.2 (2.7 ) Foreign (5.0 ) 0.5 22.6 Total deferred provision (benefit) (22.1 ) 19.0 71.1 Income tax benefits attributable to employee stock plan activity — — — Total provision (benefit) for income taxes $ 218.5 $ 248.0 $ 85.7 The provision for income taxes differs from the amount computed by applying the federal statutory rate to pretax (loss) income as follows (in millions): Years Ended December 31, 2015 2014 2013 Expected (benefit) provision at 35% rate $ 298.3 $ (30.2 ) $ 184.0 State taxes (benefit), net of federal benefit 8.9 9.5 (3.6 ) Foreign income at different tax rates (68.9 ) (90.2 ) (37.7 ) R&D tax credits (12.7 ) (17.1 ) (32.5 ) Share-based compensation 13.2 25.3 25.6 Non-deductible goodwill impairment — 297.5 — Gain on sale of Junos Pulse — 75.6 — Release of valuation allowance — (22.8 ) — Settlement with tax authorities — — (28.3 ) Domestic production activities (15.1 ) (6.8 ) (26.3 ) Non-deductible compensation 3.7 3.2 1.5 Cost sharing adjustment (13.2 ) — — Other 4.3 4.0 3.0 Total provision for income taxes $ 218.5 $ 248.0 $ 85.7 In 2015, the United States Tax Court (the “Court”) issued an opinion favorable to Altera Corporation (“Altera”) with respect to Altera’s litigation with the Internal Revenue Service (“IRS”). The litigation relates to the treatment of share-based compensation expense in an inter-company cost-sharing arrangement with Altera’s foreign subsidiary. In its opinion, the Court accepted Altera’s position of excluding share-based compensation from its inter-company cost-sharing arrangement. As a result, the Company has reversed the inclusion of share-based compensation in cost-sharing arrangement as a cumulative adjustment in the quarter ended September 30, 2015. Because this change to cost sharing increases the Company's cumulative foreign earnings, approximately $70.3 million of the gross income tax benefit associated with this change has been offset by an increase in income tax expense accrued upon the company’s foreign earnings. The Company will continue to monitor ongoing developments and potential impacts to its financial statements. The passage of Protecting Americans from Tax Hike Act of 2015, on December 18, 2015, retroactively and permanently reinstated the U.S. federal R&D tax credit effective January 1, 2015. In 2014, the Company provided tax on a pre-tax loss primarily due to the non-deductible goodwill charge. In 2013, the Company recorded $64.2 million of net income tax benefit related to items unique to the year. These amounts included $19.7 million for a multi-year claim related to the U.S. production activities deduction, $28.3 million for a tax settlement with the IRS, and $16.2 million of U.S. federal R&D tax credit resulting from the American Taxpayer Relief Act of 2012 signed on January 2, 2013, which retroactively reinstated the U.S. federal R&D tax credit from January 1, 2012 to December 31, 2013. Deferred income taxes reflect the net tax effects of tax carry-forward items and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company's long-term deferred tax assets and deferred tax liabilities are as follows (in millions): As of December 31, 2015 2014 Deferred tax assets: Net operating loss carry-forwards $ 1.0 $ 1.3 Foreign tax credit carry-forwards 75.4 69.7 Research and other credit carry-forwards 128.7 122.5 Deferred revenue 109.3 104.9 Stock-based compensation 49.1 55.8 Cost sharing adjustment 70.1 — Reserves and accruals not currently deductible 173.9 129.8 Other 19.2 19.8 Total deferred tax assets 626.7 503.8 Valuation allowance (146.2 ) (144.5 ) Deferred tax assets, net of valuation allowance 480.5 359.3 Deferred tax liabilities: Property and equipment basis differences (44.1 ) (35.6 ) Purchased intangibles (3.1 ) (16.7 ) Unremitted foreign earnings (365.4 ) (260.6 ) Deferred compensation and other (12.0 ) (5.1 ) Other — — Total deferred tax liabilities (424.6 ) (318.0 ) Net deferred tax assets (1) $ 55.9 $ 41.3 _______________________________ (1) During the year ended December 31, 2015, the Company early adopted ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the Consolidated Balance Sheets. Certain amounts in the prior-year Consolidated Financial Statements were retrospectively adjusted to conform to the current-year presentation. As of December 31, 2015 and 2014 , the Company had a valuation allowance on its U.S. domestic deferred tax assets of approximately $146.2 million and $144.5 million , respectively. The balance at December 31, 2015 consisted of approximately $128.1 million and $9.7 million against the Company's California and Massachusetts deferred tax assets, respectively, which the Company believes are not more likely than not to be utilized in future years. The remaining deferred tax assets on which the Company recorded a valuation allowance are approximately $8.4 million related to losses that are capital in nature and may carry forward to offset future capital gains only. The valuation allowance increased in 2015 by $1.7 million related to an increase in the California R&D tax credit and decreased $11.2 million in 2014 related to utilization of losses that are capital in nature offset by the increase in the California R&D tax credit. As of December 31, 2015 , the Company had California net operating loss carry-forwards of approximately $49.5 million of which $48.0 million is expected to expire unused. The Company also had California tax credit carry-forwards of approximately $237.1 million . Approximately $19.5 million of the benefit from the California tax credit carry-forwards will be credited to additional paid-in capital when realized on the Company's income tax returns. Unused net operating loss carry-forwards will expire at various dates beginning in the year 2016. The California tax credit carry-forwards will carry forward indefinitely. The Company provides U.S. income taxes on the earnings of foreign subsidiaries unless the subsidiaries' earnings are considered indefinitely reinvested outside of the United States. The Company has made no provision for U.S. income taxes on approximately $2.2 billion of cumulative undistributed earnings of certain foreign subsidiaries through December 31, 2015 . These earnings are considered indefinitely invested in operations outside of the U.S., as the Company intends to utilize these amounts to fund future expansion of its international operations. If these earnings were distributed to the United States in the form of dividends or otherwise, or if the shares of the relevant foreign subsidiaries were sold or otherwise transferred, the Company would be subject to additional U.S. income taxes (subject to an adjustment for foreign tax credits) and foreign withholding taxes. Determination of the amount of unrecognized deferred income tax liability related to these earnings is not practicable. As of December 31, 2015 , 2014 , and 2013 , the total amount of gross unrecognized tax benefits was $216.1 million , $199.2 million , and $137.6 million , respectively. As of December 31, 2015 , approximately $181.8 million of the $216.1 million gross unrecognized tax benefits, if recognized, would affect the effective tax rate. A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows (in millions): Years Ended December 31, 2015 2014 2013 Balance at beginning of year $ 199.2 $ 137.6 $ 136.1 Tax positions related to current year: Additions 18.1 62.5 15.8 Tax positions related to prior years: Additions 5.3 0.6 22.6 Reductions (2.9 ) — (2.2 ) Settlements — — (31.1 ) Lapses in statutes of limitations (3.6 ) (1.5 ) (3.6 ) Balance at end of year $ 216.1 $ 199.2 $ 137.6 As of December 31, 2015 , 2014 , and 2013 , the Company had accrued interest and penalties related to unrecognized tax benefits of $24.1 million , $22.3 million , and $18.4 million , respectively, to other long-term liabilities in the Consolidated Balance Sheets. The Company recognized an expense for net interest and penalties of $2.5 million , $2.8 million , and $0.6 million in its Consolidated Statements of Operations during the years ended December 31, 2015 , 2014 , and 2013 , respectively. The Company engages in continuous discussions and negotiations with tax authorities regarding tax matters in various jurisdictions. There is a greater than remote likelihood that the balance of the gross unrecognized tax benefits will decrease by approximately $18.6 million within the next twelve months due to lapses of applicable statutes of limitation and the completion of tax review cycles in various tax jurisdictions. In 2013, the Company executed a closing agreement with the Appeals Division of the IRS related to its intercompany R&D cost sharing arrangement for the license of intangibles acquired in 2004, 2005, and 2006. The Company reached a final resolution with the IRS on all proposed adjustments for all tax years through 2006, which resulted in a settlement of approximately $19.6 million , including interest. The Company conducts business globally and, as a result, Juniper Networks or one or more of its subsidiaries files income tax returns in the U.S. federal jurisdiction and various state and foreign jurisdictions. In the normal course of business the Company is subject to examination by taxing authorities throughout the world, including such major jurisdictions as the Netherlands, U.K., France, Germany, Japan, China, Australia, India, and the U.S. With few exceptions, the Company is no longer subject to U.S. federal, state and local, and non-U.S. income tax examinations for years before 2004. The Company is currently under examination by the IRS for the 2007 through 2009 tax years and the California Franchise Tax Board for the 2004 through 2006 tax years. In 2015, the IRS issued “Notices of Proposed Adjustments” related to the examination. The Company regularly assesses the likelihood of an adverse outcome resulting from such examinations. As of December 31, 2015, the Company believes the resolution of the audits will not have a material adverse impact on the financial statements. The Company is also subject to separate ongoing examinations by the India tax authorities for the 2003 tax year, 2004 through 2008 tax years, and the 2009 through 2010 tax years. The Company is not aware of any other examinations by tax authorities in any other major jurisdictions in which it files income tax returns as of December 31, 2015 . In 2008, the Company received a proposed adjustment from the India tax authorities related to the 2004 tax year. In 2009, the India tax authorities commenced a separate investigation of the Company's 2004 through 2008 tax returns and are disputing the Company's determination of taxable income due to the cost basis of certain fixed assets. The Company accrued $4.6 million in penalties and interest in 2009 related to this matter. The Company understands that in accordance with the administrative and judicial process in India, the Company may be required to make payments that are substantially higher than the amount accrued in order to ultimately settle this issue. The Company strongly believes that any assessment it may receive in excess of the amount accrued would be inconsistent with applicable India tax laws and intends to defend this position vigorously. The Company is pursuing all available administrative remedies relative to these matters. The Company believes that it has adequately provided for any reasonably foreseeable outcomes related to these proposed adjustments and the ultimate resolution of these matters is unlikely to have a material effect on its consolidated financial condition or results of operations; however, there is still a possibility that an adverse outcome of these matters could have a material effect on its consolidated financial condition and results of operations.

Net Income Per Share

Net Income Per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Income Per Share	Net Income per Share The Company computed basic and diluted net (loss) income per share attributable to Juniper Networks common stockholders as follows (in millions, except per share amounts): Years Ended December 31, 2015 2014 2013 Numerator: Net income (loss) $ 633.7 $ (334.3 ) $ 439.8 Denominator: Weighted-average shares used to compute basic net income (loss) per share 390.6 457.4 501.8 Dilutive effect of employee stock awards 8.8 — 8.5 Weighted-average shares used to compute diluted net income (loss) per share 399.4 457.4 510.3 Net income (loss) per share attributable to Juniper Networks common stockholders: Basic $ 1.62 $ (0.73 ) $ 0.88 Diluted $ 1.59 $ (0.73 ) $ 0.86 Anti-dilutive: Potential anti-dilutive shares 3.4 20.8 13.2 Basic net income per share is computed using net income (loss) available to common stockholders and the weighted-average number of common shares outstanding for the period. Diluted net income per share is computed using net income (loss) available to common stockholders and the weighted-average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Dilutive potential common shares consist of common shares issuable upon exercise of stock options, issuances of ESPP, and vesting of RSUs, RSAs, and PSAs. The Company includes the common shares underlying PSAs in the calculation of diluted net income per share when they become contingently issuable and excludes such shares when they are not contingently issuable. Potentially dilutive common shares were excluded from the computation of diluted net loss per share because their effect would be anti-dilutive.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Commitments Operating Leases The following table summarizes the Company’s future minimum payments under non-cancelable operating leases for each of the next five years and thereafter as of December 31, 2015 (in millions): Years Ending December 31, Amount 2016 $ 35.7 2017 25.6 2018 18.6 2019 10.3 2020 7.8 Thereafter 15.7 Total $ 113.7 The Company leases its facilities and certain equipment under non-cancelable operating leases that expire at various dates through October 31, 2024 . Certain leases require the Company to pay variable costs such as taxes, maintenance, and insurance and include renewal options and escalation clauses. Rent expense for 2015 , 2014 , and 2013 was approximately $43.2 million , $46.0 million , and $52.8 million , respectively. Data Center Lease Agreement On July 10, 2015, the Company entered into a data center lease agreement through March 2026 in which the Company has the option to extend the term of the lease for up to twenty years in increments of either five years or ten years, for approximately 63,000 square feet of space in the State of Washington. The total payment for the lease is expected to be approximately $118.1 million over the ten -year term. The lease agreement provides the Company with a tenant allowance of $6.0 million to be used for tenant leasehold improvements. Any unused tenant allowance may be applied as a credit to the rent payment. The space will be used, among other things, to consolidate certain of the Company's laboratory operations currently located in Sunnyvale, California. As the Company is subject to certain contractual obligations during the construction period, the Company is deemed the owner of the property during the construction period. Accordingly, as of December 31, 2015 , the Company capitalized the construction cost by recording a build-to-suit lease asset under construction in progress of $45.6 million , which is a component of property and equipment, net, and a corresponding build-to-suit financing liability, which is a component of other long-term liabilities, in the Consolidated Balance Sheets. Purchase Commitments with Contract Manufacturers and Suppliers In order to reduce manufacturing lead times and ensure adequate component supply, the Company enters into agreements with contract manufacturers and certain suppliers to procure inventory based on the Company's requirements. A significant portion of the Company's purchase commitments arising from these agreements consists of firm and non-cancelable commitments. These purchase commitments totaled $591.2 million as of December 31, 2015 . The Company establishes a liability in connection with purchase commitments related to quantities in excess of its demand forecasts or obsolete materials charges for components purchased by the contract manufacturers based on the Company’s demand forecast or customer orders. As of December 31, 2015 , the Company had accrued $18.0 million based on its estimate of such charges. Debt and Interest Payment on Debt As of December 31, 2015 , the Company held short-term and long-term debt consisting of senior notes with a carrying value of $299.9 million and $1,648.8 million , respectively. Of these Notes, $300.0 million will mature in 2016 and bears interest at a fixed rate of 3.10% , $300.0 million will mature in 2020 and bears interest at a rate of 3.30% , $300.0 million will mature in 2021 and bears interest at a fixed rate of 4.60% , $350.0 million will mature in 2024 and bears interest at a fixed rate of 4.50% , $300.0 million will mature in 2025 and bears interest at a fixed rate of 4.35% , and $400.0 million will mature in 2041 and bears interest at a fixed rate of 5.95% . Interest on the Notes is payable semiannually. See Note 10, Debt and Financing , for further discussion of the Company's short-term and long-term debt. Other Contractual Obligations As of December 31, 2015 , other contractual obligations primarily consisted of (1) $36.2 million in indemnity and employee-related obligations and service-related escrows, including those required in connection with certain asset purchases and acquisitions completed by the Company between 2005 and 2014; (2) $3.5 million in campus build-out obligations; and (3) $33.4 million of agreements that include firm and non-cancelable terms to transfer funds in the future for fixed or minimum amounts or quantities to be purchased at fixed or minimum prices. Tax Liabilities As of December 31, 2015 , the Company had $187.3 million included in long-term income taxes payable in the Consolidated Balance Sheets for unrecognized tax positions. At this time, the Company is unable to make a reasonably reliable estimate of the timing of payments related to this amount due to uncertainties in the timing of tax audit outcomes. Guarantees The Company enters into agreements with customers that contain indemnification provisions relating to potential situations where claims could be alleged that the Company’s products solely, or in combination with other third party products, infringe the intellectual property rights of a third-party. As of December 31, 2015 , the Company recorded a $15.0 million liability for such indemnification obligations in other accrued liabilities in the Consolidated Balance Sheets. The Company also has financial guarantees consisting of guarantees of product and service performance, guarantees related to third-party customer-financing arrangements, custom and duty guarantees, and standby letters of credit for certain lease facilities. As of December 31, 2015 and 2014 , the Company had $15.8 million and $26.2 million , respectively, in financing arrangements, bank guarantees, and standby letters of credit related to these financial guarantees, of which $9.9 million in financing guarantees was recorded in other accrued liabilities and other long-term liabilities in the Consolidated Balance Sheets as of December 31, 2015 . See Note 10, Debt and Financing , for further discussion of the Company's third-party customer financing arrangements that contain guarantee provisions. 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 Litigation In addition to the investigations discussed above, the Company is involved in other disputes, litigation, and other legal actions. The Company is aggressively defending these current litigation 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. There are many uncertainties associated with any litigation and these actions 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.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Financial Data (Unaudited)	Selected Quarterly Financial Data (Unaudited) The tables below set forth selected unaudited financial data for each quarter of the two years ended December 31, 2015 (in millions, except per share amounts): Year Ended December 31, 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues: Product $ 764.1 $ 899.7 $ 925.4 $ 973.9 Service 303.3 322.5 323.2 345.7 Total net revenues 1,067.4 1,222.2 1,248.6 1,319.6 Cost of revenues: Product 288.8 311.7 322.6 346.5 Service 121.3 129.0 128.6 130.7 Total cost of revenues 410.1 440.7 451.2 477.2 Gross margin 657.3 781.5 797.4 842.4 Operating expenses: Research and development 248.7 251.6 247.0 247.2 Sales and marketing 220.2 232.4 235.3 255.9 General and administrative 55.2 56.3 57.1 60.3 Restructuring and other charges (benefit) 1.4 (1.9 ) — (0.1 ) Total operating expenses 525.5 538.4 539.4 563.3 Operating income 131.8 243.1 258.0 279.1 Other expense, net (1)(3) (15.8 ) (17.1 ) (8.4 ) (18.5 ) Income before income taxes 116.0 226.0 249.6 260.6 Income tax provision (2) 35.8 68.0 51.9 62.8 Net income $ 80.2 $ 158.0 $ 197.7 $ 197.8 Net income per share: (4) Basic $ 0.20 $ 0.41 $ 0.52 $ 0.52 Diluted $ 0.19 $ 0.40 $ 0.51 $ 0.51 Cash dividends declared per common stock (5) $ 0.10 $ 0.10 $ 0.10 $ 0.10 _______________________________ (1) During the first quarter of 2015, the Company issued $300.0 million aggregate principal amount of 3.30% senior notes due 2020 and $300.0 million aggregate principal amount of 4.35% senior notes due 2025. As a result, the Company recorded interest expense of $19.1 million , related to long-term debt issued in 2015 in other expense, net during the year ended December 31, 2015 . (2) Includes approximately $13.2 million net benefit of cumulative adjustment related to the change in treatment of share-based compensation as a result of the U.S. Tax Court decision in Altera Corporation et al., or Altera, v. Commissioner. See Note 14, Income Taxes, in Notes to the Consolidated Financial Statements in Item 8 of Part II of this Report for further information. (3) During the fourth quarter of 2015, the Company recorded a gain on privately held investments of $7.3 million in other expense, net. (4) Net income per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period. (5) On January 27, 2015, April 23, 2015, July 23, 2015 and on October 22, 2015, the company declared a quarterly cash dividend of $0.10 per share of common stock to stockholders on record as of the close of business March 3, 2015, June 2, 2015, September 1, 2015, and December 1, 2015, respectively. Year Ended December 31, 2014 First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues: Product $ 876.0 $ 929.2 $ 809.5 $ 794.0 Service 294.1 300.3 316.4 307.6 Total net revenues 1,170.1 1,229.5 1,125.9 1,101.6 Cost of revenues: Product 326.6 359.3 290.0 310.9 Service 123.4 122.0 121.1 115.6 Total cost of revenues (1) 450.0 481.3 411.1 426.5 Gross margin 720.1 748.2 714.8 675.1 Operating expenses: Research and development 264.0 255.5 253.2 233.5 Sales and marketing 273.4 258.0 249.2 243.0 General and administrative 74.9 60.6 55.0 40.6 Restructuring and other charges (benefits) (1) 114.0 58.2 (15.0 ) 9.8 Impairment of goodwill (2) — — — 850.0 Total operating expenses 726.3 632.3 542.4 1,376.9 Operating (loss) income (6.2 ) 115.9 172.4 (701.8 ) Other income (expense), net (3) 154.2 178.6 (6.8 ) 7.4 Income (loss) before income taxes 148.0 294.5 165.6 (694.4 ) Income tax provision 37.4 73.4 62.0 75.2 Net income (loss) $ 110.6 $ 221.1 $ 103.6 $ (769.6 ) Net income (loss) per share: (4) Basic $ 0.23 $ 0.47 $ 0.23 $ (1.81 ) Diluted $ 0.22 $ 0.46 $ 0.23 $ (1.81 ) Cash dividends declared per common stock (5) $ — $ — $ 0.10 $ 0.10 _______________________________ (1) In the first quarter of 2014, the company initiated a 2014 Restructuring Plan, which consisted of $84.7 million asset write-downs, $28.0 million of severance costs, and $0.8 million of contract terminations that were recorded in restructuring and other charges. In addition, the Company recorded inventory write-downs related to the acceleration of the end-of-service life of certain products totaling $8.4 million to cost of revenues. In the second quarter, the Company recorded $9.9 million of severance costs, $37.6 million of facility consolidation and closures, $8.9 million of asset write-downs, and $1.5 million of contract terminations that were recorded to restructuring and other charges. The Company also recorded inventory write-downs of $11.5 million and a charge related to products with contract manufacturers of $2.3 million for acceleration of the end-of-life service of certain products to cost of revenues. In the third quarter, the Company recorded $7.1 million of severance costs, a benefit of $25.0 million of facility consolidation and closures as a result of a lease assignment, and $2.9 million of asset write-downs, that were recorded to restructuring and other (credit) charges. In the fourth quarter, the Company recorded $6.9 million in severance costs, $1.6 million of facility consolidation and closures, and $20.6 million in asset impairment and write-downs. (2) During the fourth quarter of 2014, the Company recorded an $850.0 million goodwill impairment charge related to its Security reporting unit. (3) In the first quarter of 2014, the Company recorded a gain of $163.0 million related to the sale of investments which were converted from privately-held investments to publicly-traded equity upon initial public offering. In the second quarter, the Company entered into a settlement agreement with Palo Alto Networks, which resulted in a realized gain on legal settlement of $195.3 million , net of legal fees. All such Palo Alto Networks securities were sold in the third quarter, and the Company recorded an additional $0.8 million gain. In the fourth quarter, the Company recorded a gain of $19.6 million on the sale of Junos Pulse. (4) Net income (loss) per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period. (5) On July 22, 2014 and October 23, 2014 the company declared a quarterly cash dividend of $0.10 per share of common stock to stockholders on record as of the close of business September 2, 2014 and December 2, 2014, respectively.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Business Combination In January 2016, the Company entered into a definitive agreement to acquire BTI Systems Inc., a provider of cloud and metro optical networking systems and software to content, cloud and service providers, for (i) approximately $65.0 million in cash (inclusive of debt) plus cash on hand at closing and (ii) the assumption of restricted stock units outstanding at closing. The Company believes that this acquisition will allow the Company to accelerate the delivery of open and automated packet optical transport solutions with integrated network management based on BTI Systems' proNX Service Manager and Juniper's Connectivity Services Director, as well as NorthStar Controller. The Company believes that, together, these products provide a unified management interface for multi-layer provisioning of end-to-end services across IP and optical networks. The consummation of this acquisition is subject to customary closing conditions. Dividend Declaration On January 27, 2016, the Company announced that it had declared a quarterly cash dividend of $0.10 per share of common stock payable on March 22, 2016 to stockholders of record as of the close of business on March 1, 2016. Stock Repurchase Activities Subsequent to December 31, 2015, through the filing of this Annual Report on Form 10-K, the Company repurchased 3.1 million shares of its common stock, for an aggregate purchase price of $75.0 million at an average price of $23.89 per share, under the 2014 Stock Repurchase Program and were settled prior to the filing of this Report. Under the 2014 Stock Repurchase Program, the Company has $457.5 million authorized funds remaining as of the filing date. Purchases under the Company's stock repurchase program are subject to review of the circumstances in place at the time and will be made from time to time as permitted by securities law and other legal requirements. This program may be discontinued at any time.

Schedule II- Valuation and Qual

Schedule II- Valuation and Qualifying Account	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Account	Allowance for Doubtful Accounts Balance at Beginning of Year Charged to (Reversed from) Costs and Expenses Write-offs, Net of Recoveries Balance at End of Year 2015 $ 4.7 $ 6.5 $ (1.9 ) $ 9.3 2014 $ 5.4 $ (0.7 ) $ — $ 4.7 2013 $ 9.5 $ (3.8 ) $ (0.3 ) $ 5.4 Additions Sales Return Reserve Balance at Beginning of Year Charged as a Reduction in Revenues Charged to Other Accounts Used Balance at End of Year 2015 $ 50.2 $ 65.4 $ 92.6 $ (137.0 ) $ 71.2 2014 $ 49.0 $ 53.2 $ 80.9 $ (132.9 ) $ 50.2 2013 $ 52.7 $ 35.0 $ 61.5 $ (100.2 ) $ 49.0

Significant Accounting Polici28

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of the financial statements and related disclosures in conformity with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Consolidated Financial Statements and the accompanying notes. The Company bases its estimates and assumptions on current facts, historical experience, and various other factors that it believes are reasonable under the circumstances, to determine the carrying values of assets and liabilities that are not readily apparent from other sources. To the extent there are material differences between the Company's estimates and the actual results, the Company's future consolidated results of operation may be affected.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist of cash on hand, demand deposits with banks, highly liquid investments in money market funds, commercial paper, government securities, certificates of deposit, and corporate debt securities, which are readily convertible into cash. All highly liquid investments purchased with original maturities of three months or less are classified as cash and cash equivalents.
Investments in Available-for-Sale and Trading Securities	Investments in Available-for-Sale and Trading Securities The Company's investments in publicly-traded debt and equity securities are classified as available-for-sale. Available-for-sale investments are initially recorded at cost and periodically adjusted to fair value in the Consolidated Balance Sheets. Unrealized gains and losses on these investments are reported as a separate component of accumulated other comprehensive income. Realized gains and losses are determined based on the specific identification method and are reported in the Consolidated Statements of Operations. The Company periodically evaluates its investments to determine if impairment charges are required. The Company considers various factors in determining whether to recognize an impairment charge, including the length of time the investment has been in a loss position, the extent to which the fair value has been less than the Company's cost basis, the investment's financial condition, and near-term prospects of the investee. If the Company determines that the decline in an investment's fair value is other than temporary, the difference is recognized as an impairment loss in its Consolidated Statements of Operations. The Company's non-qualified compensation plan is invested in mutual funds which are classified as trading securities and reported at fair value in the Consolidated Balance Sheets. The realized and unrealized holding gains and losses are reported in the Consolidated Statements of Operations.
Privately-Held Investments	Privately-Held Investments The Company has privately-held investments included in other long-term assets in the 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. The investments carried at cost are adjusted for any impairment, as the Company does not have a controlling interest and does not have the ability to exercise significant influence over these companies. These investments are inherently high risk as the market for technologies or products manufactured by these companies are usually in their early stages at the time of the investment by the Company and such markets may never be significant. The Company measures the fair value of privately-held investments using an analysis of the financial conditions and near term prospects of the investees, including recent financing activities and their capital structure. Realized gains and losses, if any, are reported in the Consolidated Statements of Operations.
Fair Value	Fair Value Fair value is defined as the price that would be received upon sale of an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining fair value, the Company considers the principal or most advantageous market in which it transacts, and considers assumptions that market participants would use when pricing the asset or liability. The Company applies the following fair value hierarchy, which prioritizes the inputs used to measure fair value into three levels and bases the categorization within the hierarchy upon the lowest level of input that is available and significant to the fair value measurement: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. These inputs are valued using market based approaches. Level 3 – Inputs are unobservable inputs based on the Company’s assumptions. These inputs, if any, are valued using internal financial models.
Derivatives	Derivatives The Company uses derivatives to partially offset its market exposure to fluctuations in certain foreign currencies. The Company does not enter into derivatives for speculative or trading purposes. The Company uses foreign currency forward contracts to hedge certain forecasted foreign currency transactions relating to operating expenses. These derivatives are designated as cash flow hedges. Execution of these cash flow hedge derivatives typically occurs every month with maturities of one year or less. These derivatives are carried at fair value and the effective portion of the derivative's gain or loss is initially reported as a component of accumulated other comprehensive income, and upon occurrence of the forecasted transaction, is subsequently reclassified into the costs of services or operating expense line item to which the hedged transaction relates. The Company records any ineffectiveness of the hedging instruments in other (expense) income, net, on its Consolidated Statements of Operations. Cash flows from such hedges are classified as operating activities. All amounts within other comprehensive income are expected to be reclassified into earnings within the next twelve months. The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain monetary assets and liabilities denominated in non-functional currencies. These derivatives are carried at fair value with changes recorded in other (expense) income, net in the Consolidated Statements of Operations in the same period as the changes in the fair value from the re-measurement of the underlying assets and liabilities. Cash flows from such derivatives are classified as operating activities. These foreign exchange forward contracts have maturities of one year or less.
Inventory	Inventory Inventory consists primarily of component parts to be used in the manufacturing process and finished goods in-transit, and is stated at the lower of cost or market. Cost is computed using standard cost, which approximates actual cost, on a first-in, first-out basis. A charge is recorded to cost of product when inventory is determined to be in excess of anticipated demand or considered obsolete. At the point of loss recognition, a new, lower-cost basis for that inventory is established, and subsequent changes in facts and circumstances do not result in the restoration or increase in the newly established cost basis.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost less accumulated depreciation. Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 3 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 5 to 40 Leasehold improvements Lease term, not to exceed 10 years Construction in progress is related to the construction or development of property and equipment that have not yet been placed in service for their intended use. Depreciation for computers, equipment, software, furniture and fixtures commences once they are placed in service. Depreciation for buildings, land and leasehold improvements commences once they are ready for their intended use.
Goodwill and Other Long-Lived Assets	Goodwill and Other Long-Lived Assets Goodwill represents the future economic benefits arising from other assets acquired in a business combination or an acquisition that are not individually identified and separately recorded. The excess of the purchase price over the estimated fair value of net assets of businesses acquired in a business combination is recognized as goodwill. Goodwill is tested for impairment annually during the fourth quarter or more frequently if certain circumstances indicate the carrying value of goodwill is impaired. A qualitative assessment is first made to determine whether it is necessary to quantitatively test goodwill for impairment. This initial assessment includes, among others, consideration of macroeconomic conditions and financial performance. If the qualitative assessment indicates that it is more likely than not that an impairment exists, a quantitative analysis is performed by comparing the estimated fair values of our reporting units with their respective carrying values, including goodwill. An impairment loss is recognized to the extent that the carrying amount of goodwill exceeds the asset's implied fair value. Other intangible assets acquired in a business combination and determined to have an indefinite useful life are not amortized but are assessed for potential impairment annually or when events or circumstances indicate that their carrying amounts might be impaired. Long-lived assets, such as property, plant, and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset, or asset group, to estimated undiscounted future cash flows expected to be generated by the asset, or asset group. An impairment charge is recognized by the amount by which the carrying amount of the asset, or asset group, exceeds its fair value. The Company amortizes intangible assets with estimable useful lives on a straight-line basis over their useful lives.
Revenue Recognition	Revenue Recognition Revenue is recognized when all of the following criteria have been met: • Persuasive evidence of an arrangement exists. The Company generally relies upon sales contracts or agreements, and customer purchase orders to determine the existence of an arrangement. • Delivery has occurred. The Company uses shipping terms and related documents, or written evidence of customer acceptance, when applicable, to verify delivery or performance. • Sales price is fixed or determinable. The Company assesses whether the sales price is fixed or determinable based on the payment terms and whether the sales price is subject to refund or adjustment. • Collectability is reasonably assured. The Company assesses collectability based on creditworthiness of customers as determined by its credit checks, their payment histories, or changes in circumstances that indicate that collectability is not reasonably assured. When sales arrangements contain multiple elements the Company allocates revenue to each element based on a selling price hierarchy. The selling price for a deliverable is based on either vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”) if VSOE is not available, or estimated selling price (“ESP”) if neither VSOE nor TPE is available. The Company then recognizes revenue on each deliverable in accordance with its policies for product and service revenue recognition. VSOE of selling price is based on the price charged when the element is sold separately. In determining VSOE, the Company requires that a substantial majority of the selling prices fall within a reasonable range based on historical discounting trends for specific products and services. TPE of selling price is established by evaluating largely interchangeable competitor products or services in stand-alone sales to similar situated customers. However, as the Company's products contain a significant element of proprietary technology and its solutions offer substantially different features and functionality, the comparable pricing of third-party products with similar functionality typically cannot be obtained and therefore TPE is not used. ESP is established considering multiple factors including, but not limited to pricing practices in different geographies and through different sales channels, gross margin objectives, internal costs, competitor pricing strategies, and industry technology lifecycles. In multiple element arrangements where software deliverables are included, revenue is allocated to each separate unit of accounting for each of the non-software deliverables and to the software deliverables as a group using the relative selling prices of each of the deliverables in the arrangement based on the aforementioned selling price hierarchy. If the arrangement contains more than one software deliverable, the arrangement consideration allocated to the software deliverables as a group is then allocated to each software deliverable using the residual method when VSOE of fair value of the undelivered items exists. Under the residual method, the amount of revenue allocated to delivered elements equals the total arrangement consideration less the aggregate fair value of any undelivered elements. If VSOE of one or more undelivered items does not exist, revenue from the entire arrangement is deferred and recognized at the earlier of: (i) delivery of those elements or (ii) when fair value can be established unless maintenance services is the only undelivered element, in which case, the entire arrangement fee is recognized ratably over the maintenance service period. The Company limits the amount of revenue recognition for delivered elements to the amount that is not contingent on the future delivery of products or services or subject to customer-specific return or refund privileges. The Company records reductions to revenue for estimated product returns and pricing adjustments, such as rebates and price protection, in the same period that the related revenue is recorded. The amount of these reductions is based on historical sales returns and price protection credits, specific criteria outlined in rebate agreements, and other factors known at the time. A portion of the Company's sales is made through distributors under agreements allowing for pricing credits or rights of return. As reliable estimates of these credits or returns cannot be made, product revenue on sales made through these distributors is recognized upon sell-through as reported by the distributors to the Company. Deferred revenue on shipments to distributors reflects the effects of distributor pricing credits given and the amount of gross margin expected to be realized upon sell-through. Deferred revenue is recorded net of the related product costs of revenue. Service revenues include revenue from maintenance, training, and professional services. Maintenance is offered under renewable contracts. Revenue from maintenance service contracts is deferred and recognized ratably over the contractual support period, which is generally one to three years . Revenue from training and professional services is recognized as services are completed or ratably over the contractual period, which is generally one year or less.
Allowance For Doubtful Accounts	Allowance for Doubtful Accounts The allowance for doubtful accounts is based on the Company's assessment of the collectability of customer accounts. The Company regularly reviews its receivables that remain outstanding past their applicable payment terms and establishes an allowance by considering factors such as historical experience, credit quality, and age of the accounts receivable balances, and current economic conditions that may affect a customer's ability to pay.
Warranty Reserves	Warranty Reserves The Company generally offers a one -year warranty on most of its hardware products, and a 90 -day warranty on the media that contains the software embedded in the products. Warranty costs are recognized as part of the Company's cost of sales based on associated material costs, logistics costs, labor costs, and overhead at the time revenue is recognized. Material costs are estimated primarily based upon the historical costs to repair or replace product returns within the warranty period. Labor, logistics and overhead costs are estimated primarily based upon historical trends in the cost to support customer cases within the warranty period.
Contract Manufacturer Liabilities	Contract Manufacturer Liabilities The Company establishes a liability for non-cancelable, non-returnable purchase commitments with its contract manufacturers for carrying charges, quantities in excess of its demand forecasts, or obsolete material charges for components purchased by the contract manufacturers to meet the Company’s demand forecast or customer orders. The demand forecasts are based upon historical trends and analysis from the Company's sales and marketing organizations, adjusted for overall market conditions.
Research and Development	Research and Development Costs to research, design, and develop the Company's products are expensed as incurred.
Software Development Costs	Software Development Costs Capitalization of software development costs for software to be sold, leased, or otherwise marketed begins when a product's technological feasibility has been established and ends when a product is available for general release to customers. Generally, the Company's products are released soon after technological feasibility has been established. As a result, costs incurred between achieving technological feasibility and product general availability have not been significant. The Company capitalizes costs associated with internal-use software systems during the application development stage. Such capitalized costs include external direct costs utilized in developing or obtaining the applications and payroll and payroll-related costs for employees, who are directly associated with the development of the applications.
Advertising	Advertising Advertising costs are charged to sales and marketing expense as incurred.
Foreign Currency	Foreign Currency Assets and liabilities of foreign operations with non-U.S. Dollar functional currency are translated to U.S. Dollars using exchange rates in effect at the end of the period. Revenue and expenses are translated to U.S. Dollars using average exchange rates for the period. The resulting translation adjustments are included in the Company’s Consolidated Balance Sheets in the stockholders’ equity section as a component of accumulated other comprehensive income. For the Company's international subsidiaries in which the functional currency is the U.S. dollar, the Company records foreign exchange gains and losses for assets and liabilities denominated in non-U.S. dollar currencies. These remeasurement adjustments are recorded in other (expense) income, net in the Consolidated Statements of Operations.
Loss Contingencies	Loss Contingencies The Company is subject to the possibility of various loss contingencies arising in the ordinary course of business. Management considers the likelihood of loss related to an asset, or the incurrence of a liability, as well as its ability to reasonably estimate the amount of loss, in determining loss contingencies. An estimated loss contingency is accrued when it is probable that an asset has been impaired or a liability has been incurred and the amount of loss can be reasonably estimated. The Company regularly evaluates current information available to determine whether such accruals should be adjusted and whether new accruals are required.
Share-Based Compensation	Share-Based Compensation The Company measures and recognizes compensation cost for all share-based awards made to employees and directors, including employee stock options, stock awards, stock units, and employee stock purchases related to the Employee Stock Purchase Plan ("ESPP"). Share-based compensation expense is based on the fair value of the underlying awards and amortized on a straight-line basis, net of estimated forfeitures. The Company utilizes the Black-Scholes-Merton (“BSM”) option-pricing model to estimate the fair value of its stock options and ESPP shares. The BSM model requires various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, expected life, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the most recent period commensurate with the estimated expected life of the Company’s stock options and ESPP. The expected life of a stock option is based on historical experience of employee exercises and post-vesting termination behavior as well as the potential effect from options that have not been exercised. The expected life of ESPP approximates the offering period. The Company determines the fair value of its restricted stock units ("RSUs"), restricted stock awards ("RSAs"), and performance share awards ("PSAs") based on the closing market price of the Company’s common stock on the date of grant, adjusted by the present value of the expected dividend. For market-based RSUs, the Company estimates the fair value and derived service period using the Monte Carlo simulation option pricing model ("Monte Carlo model"). The determination of the grant date fair value and derived service periods using the Monte Carlo model is affected by the Company's stock price as well as various highly subjective assumptions that represent management's best estimates of volatility, risk-free interest rate, and dividend yield. The Company estimates expected volatility based on the implied volatility of market-traded options, on the Company's common stock, adjusted for other relevant factors including historical volatility of the Company’s common stock over the contractual life of the Company's market-based RSUs.
Provision for Income Taxes	Provision for Income Taxes Deferred tax assets and liabilities are recognized for the expected tax consequences of temporary differences between the tax bases of assets and liabilities and their reported amounts. Valuation allowances are recorded to reduce deferred tax assets to the amount that will more likely than not be realized. The Company accounts for uncertainty in income taxes using a two-step approach to recognize and measure uncertain tax positions. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely of being realized upon settlement. The Company classifies the liability for unrecognized tax benefits as current to the extent that the Company anticipates payment (or receipt) of cash within one year . Interest and penalties related to uncertain tax positions are recognized in the provision for income taxes.
Concentrations of Risk	Concentrations of Risk Financial instruments that subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents, investments, and accounts receivable. The Company invests only in high-quality credit instruments and maintains its cash, cash equivalents and available-for-sale investments in fixed income securities with several high-quality institutions. Deposits held with banks, including those held in foreign branches of global banks, may exceed the amount of insurance provided on such deposits. These deposits may be redeemed upon demand and, therefore, bear minimal credit risk. The Company’s derivatives expose it to credit risk to the extent that counterparties may be unable to meet the terms of the agreement. To mitigate concentration of risk related to its derivatives, the Company establishes counterparty limits to major credit-worthy financial institutions. In addition, the potential risk of loss with any one counterparty resulting from this type of credit risk is monitored and the derivatives transacted with these entities are relatively short in duration. Therefore, the Company does not expect material losses as a result of defaults by counterparties. Generally, credit risk with respect to accounts receivable is diversified due to the number of entities comprising the Company's customer base and their dispersion across different geographic locations throughout the world. The Company performs ongoing credit evaluations of its customers and generally does not require collateral on accounts receivable. During the years ended December 31, 2015 , 2014 , and 2013 , no single customer accounted for 10% or more of net revenues. The Company relies on sole suppliers for certain of its components such as application-specific integrated circuits ("ASICs") and custom sheet metal. Additionally, the Company relies primarily on a limited number of significant independent contract manufacturers and outside design manufacturers for the production of its products. The inability of any supplier or manufacturer to fulfill supply requirements of the Company could negatively impact future operating results.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In January 2016, the Financial Accounting Standards Board ("FASB") issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities ("ASU 2016-01"), which requires equity investments to be measured at fair value with changes in fair value recognized in net income and simplifies the impairment assessment of equity investments without readily determinable fair values by requiring a qualitative assessment to identify impairment. Entities may choose a practical expedient, to estimate the fair value of certain equity securities that do not have readily determinable fair value. If the practical expedient is elected, these investments would be recorded at cost, less impairment and subsequently adjusted for observable price changes. 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 September 2015, the FASB issued ASU No. 2015-16 (Topic 805) - Business Combinations: Simplifying the Accounting for Measurement-Period Adjustments ("ASU 2015-16") , which replaces the requirement that an acquirer in a business combination account for measurement period adjustments retrospectively, with a requirement that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. ASU 2015-16 requires the entity to record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendment requires an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. ASU 2015-16 is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The amendment should be applied prospectively to adjustments to provisional amounts that occur after the effective date of the guidance, with early adoption permitted for financial statements that have not been issued. The adoption of this standard will apply upon execution of a business combination. In July 2015, the FASB issued ASU No. 2015-11 (Subtopic 330) - Simplifying the Measurement of Inventory ("ASU 2015-11"), which provides guidance to companies who account for inventory using either the first-in, first-out ("FIFO") or average cost methods. The guidance states that companies should measure inventory at the lower of cost and net realizable value. Net realizable value is defined as the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. ASU 2015-11 is effective for fiscal years beginning after December 15, 2016. Early adoption is permitted. The adoption of this standard will not have a significant impact on the Company's Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-05 (Subtopic 350-40) - Customer's Accounting for Fees Paid in a Cloud Computing Arrangement ("ASU 2015-05"), which provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. The ASU also eliminates the existing requirement that customers analogize to the guidance on leases in ASC 840 to determine the asset acquired in a software licensing arrangement. Instead, customers will account for software licenses that are obtained for internal-use in the same manner as licenses of other intangible assets. ASU 2015-05 is effective for fiscal years, beginning after December 15, 2015. Early adoption is permitted. The Company plans to adopt the ASU prospectively for all new transactions entered into or materially modified after the date of adoption. In April 2015, the FASB issued ASU No. 2015-03 (Subtopic 835-30) - Simplifying the Presentation of Debt Issuance Costs ("ASU 2015-03"), which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard would reduce the debt issuance cost asset on the Company's Consolidated Balance Sheet by approximately $11.0 million and correspondingly reduce its debt liabilities by approximately $11.0 million . The Company plans to adopt this standard in the first quarter of 2016. The adoption of this standard will not have an impact to the Consolidated Statement of Operations. In August 2015, the FASB issued ASU No. 2015-15, Interest - Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements ("ASU 2015-03") . ASU 2015-15 provides additional guidance to ASU 2015-03, which did not address presentation or subsequent measurement of debt issuance costs related to line-of-credit arrangements. The amendment states that an entity may defer and present debt issuance costs associated with line-of-credit arrangements as an asset and subsequently amortize the deferred debt issuance costs ratably over the term of the line-of-credit arrangement, regardless of whether there are any outstanding borrowings on the line-of-credit arrangement. The adoption of ASU 2015-15 will not have an impact on the Company's Consolidated Financial Statements. In November 2014, the FASB issued ASU No. 2014-16 (Topic 815) - Derivatives and Hedging ("ASU 2014-16), which provides clarification on how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features in evaluating the host contract and that no single term or feature would necessarily determine the economic characteristics and risks of the host contract. ASU 2014-16 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The amendment should be applied on a modified retrospective basis to existing hybrid financial instruments issued in the form of a share as of the beginning of the year for which the amendments are effective. Early adoption is permitted. The adoption of this standard will not have a material impact on the Company's Consolidated Financial Statements. In June 2014, the FASB issued ASU No. 2014-12 (Topic 718) - Compensation - Stock Compensation (“ASU 2014-12”), which provides guidance that a performance target that affects vesting of a share-based payment and that could be achieved after the requisite service period is a performance condition. As a result, the target is not reflected in the estimation of the award’s grant date fair value. Compensation cost for such an award would be recognized over the required service period, if it is probable that the performance condition will be achieved. ASU 2014-12 is effective for all entities for annual periods beginning after December 15, 2015 and interim periods within those annual periods. ASU 2014-12 should be applied on a prospective basis to awards that are granted or modified on or after the effective date. The adoption of this standard will not have an impact on the Company's Consolidated Financial Statements. In May 2014, the FASB issued ASU No. 2014-09 (Topic 606) —Revenue from Contracts with Customers (“ASU 2014-09”), which provides guidance for revenue recognition. This ASU affects all contracts that the Company enters into with customers to transfer goods and services or for the transfer of nonfinancial assets. This ASU will supersede the revenue recognition requirements in Topic 605, and most industry specific guidance. This ASU also supersedes some cost guidance included in Subtopic 605-35, Revenue Recognition-Construction-Type and Production-Type Contracts. The standard's core principle 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. In doing so, the Company will need to use additional judgment and estimates than under the existing guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. In August 2015, the FASB issued ASU 2015-14 which deferred the effective date of the new revenue standard from December 15, 2016 to December 15, 2017, with early adoption permitted as of annual reporting periods beginning after December 15, 2016. Accordingly, the ASU will be effective for the Company beginning fiscal year 2018. The Company is currently evaluating the impact of the adoption of this standard on its Consolidated Financial Statements.

Significant Accounting Polici29

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Property and equipment useful life	Depreciation is calculated using the straight-line method, over the estimated useful lives of the following assets: Estimated Useful Life (years) Computers, equipment, and software 3 to 7 Furniture and fixtures 5 to 7 Building and building improvements 7 to 40 Land improvements 5 to 40 Leasehold improvements Lease term, not to exceed 10 years

Business Combinations (Tables)

Business Combinations (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of purchase consideration allocation for acquisitions	The following table presents the purchase consideration allocations for these acquisitions based upon acquisition-date fair values, including cash and cash equivalents acquired (in millions): 2014 Acquisition 2013 Acquisition Net tangible assets acquired $ — $ 0.1 Net liabilities acquired (2.7 ) — Intangible assets acquired 17.8 9.9 Goodwill 13.6 — Total $ 28.7 $ 10.0
Finite-Lived and Indefinite-Lived Intangible Assets Acquired as Part of Business Combination	The following table presents details of the Company's intangible assets acquired through the business combination completed during the twelve months ended December 31, 2014 (in millions, except years): Weighted Average Estimated Useful Life (In Years) Amount Existing technology 7 $ 10.7 Customer relationships 7 6.0 Trade name 4 0.6 Backlog 1 0.2 Non-compete agreements 2 0.3 Total 7 $ 17.8

Cash Equivalents and Investme31

Cash Equivalents and Investments (Tables)	12 Months Ended
	Dec. 31, 2015
Cash Equivalents and Investments [Abstract]
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 December 31, 2015 and December 31, 2014 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2015 Fixed income securities: Asset-backed securities $ 312.2 $ — $ (0.5 ) $ 311.7 Certificates of deposit 9.6 — — 9.6 Commercial paper 17.7 — — 17.7 Corporate debt securities 913.8 0.2 (2.6 ) 911.4 Foreign government debt securities 16.5 — — 16.5 Government-sponsored enterprise obligations 204.1 — (0.4 ) 203.7 U.S. government securities 278.0 — (0.4 ) 277.6 Total fixed income securities 1,751.9 0.2 (3.9 ) 1,748.2 Money market funds 29.7 — — 29.7 Mutual funds 6.1 0.1 — 6.2 Publicly-traded equity securities 8.7 0.8 (0.7 ) 8.8 Total available-for-sale securities 1,796.4 1.1 (4.6 ) 1,792.9 Trading securities in mutual funds (1) 17.7 — — 17.7 Total $ 1,814.1 $ 1.1 $ (4.6 ) $ 1,810.6 Reported as: Cash equivalents $ 3.4 $ — $ — $ 3.4 Restricted investments 35.8 0.1 — 35.9 Short-term investments 527.2 0.9 (1.0 ) 527.1 Long-term investments 1,247.7 0.1 (3.6 ) 1,244.2 Total $ 1,814.1 $ 1.1 $ (4.6 ) $ 1,810.6 ________________________________ (1) Balance includes the Company's non-qualified deferred compensation plan assets. Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value As of December 31, 2014 Fixed income securities: Asset-backed securities $ 269.3 $ — $ (0.3 ) $ 269.0 Certificates of deposit 10.6 — — 10.6 Commercial paper 20.3 — — 20.3 Corporate debt securities 738.6 0.5 (1.1 ) 738.0 Foreign government debt securities 24.6 — — 24.6 Government-sponsored enterprise obligations 162.2 — (0.1 ) 162.1 U.S. government securities 246.1 — (0.1 ) 246.0 Total fixed income securities 1,471.7 0.5 (1.6 ) 1,470.6 Money market funds 594.2 — — 594.2 Mutual funds 3.9 0.1 — 4.0 Publicly-traded equity securities 2.1 — (0.1 ) 2.0 Total available-for-sale securities 2,071.9 0.6 (1.7 ) 2,070.8 Trading securities in mutual funds (1) 16.3 — — 16.3 Total $ 2,088.2 $ 0.6 $ (1.7 ) $ 2,087.1 Reported as: Cash equivalents $ 576.6 $ — $ — $ 576.6 Restricted investments 45.2 — — 45.2 Short-term investments 332.2 0.2 (0.2 ) 332.2 Long-term investments 1,134.2 0.4 (1.5 ) 1,133.1 Total $ 2,088.2 $ 0.6 $ (1.7 ) $ 2,087.1 _______________________________ (1) Balance includes the Company's non-qualified deferred compensation plan assets.
Maturities of fixed income securities	The following table presents the contractual maturities of the Company's total fixed income securities as of December 31, 2015 (in millions): Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Due in less than one year $ 504.1 $ 0.1 $ (0.3 ) $ 503.9 Due between one and five years 1,247.8 0.1 (3.6 ) 1,244.3 Total $ 1,751.9 $ 0.2 $ (3.9 ) $ 1,748.2
Available-for-sale investments in an unrealized loss position	The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of December 31, 2015 and December 31, 2014 (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 December 31, 2015 Fixed income securities: Asset-backed securities $ 274.2 $ (0.4 ) $ 30.8 $ (0.1 ) $ 305.0 $ (0.5 ) Certificates of deposit (1) 3.3 — — — 3.3 — Corporate debt securities 687.9 (2.3 ) 58.9 (0.3 ) 746.8 (2.6 ) Foreign government debt securities (1) 9.5 — — — 9.5 — Government-sponsored enterprise obligations 185.3 (0.4 ) — — 185.3 (0.4 ) U.S. government securities 259.3 (0.4 ) — — 259.3 (0.4 ) Total fixed income securities 1,419.5 (3.5 ) 89.7 (0.4 ) 1,509.2 (3.9 ) Publicly-traded equity securities 2.1 (0.7 ) — — 2.1 (0.7 ) Total available-for sale securities $ 1,421.6 $ (4.2 ) $ 89.7 $ (0.4 ) $ 1,511.3 $ (4.6 ) ________________________________ (1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2015 . 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, 2014 Fixed income securities: Asset-backed securities $ 221.9 $ (0.3 ) $ — $ — $ 221.9 $ (0.3 ) Corporate debt securities 515.9 (1.1 ) — — 515.9 (1.1 ) Foreign government debt securities (1) 24.6 — — — 24.6 — Government-sponsored enterprise obligations 113.8 (0.1 ) — — 113.8 (0.1 ) U.S. government securities 189.0 (0.1 ) — — 189.0 (0.1 ) Total fixed income securities 1,065.2 (1.6 ) — — 1,065.2 (1.6 ) Publicly-traded equity securities 2.0 (0.1 ) — — 2.0 (0.1 ) Total available-for-sale securities $ 1,067.2 $ (1.7 ) $ — $ — $ 1,067.2 $ (1.7 ) ________________________________ (1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2014 .

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables provide a summary of assets and liabilities measured at fair value on a recurring basis and as reported in the Consolidated Balance Sheets (in millions): Fair Value Measurements at December 31, 2015 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 $ — $ 311.7 $ — $ 311.7 Certificates of deposit — 9.6 — 9.6 Commercial paper — 17.7 — 17.7 Corporate debt securities — 911.4 — 911.4 Foreign government debt securities — 16.5 — 16.5 Government-sponsored enterprise obligations — 203.7 — 203.7 Money market funds (1) 29.7 — — 29.7 Mutual funds (2) 6.2 — — 6.2 Publicly-traded equity securities 8.8 — — 8.8 U.S. government securities 247.3 30.3 — 277.6 Total available-for-sale securities 292.0 1,500.9 — 1,792.9 Trading securities in mutual funds (3) 17.7 — — 17.7 Privately-held debt and redeemable preferred stock securities — — 60.2 60.2 Derivative assets: Foreign exchange contracts — 0.4 — 0.4 Total assets measured at fair value $ 309.7 $ 1,501.3 $ 60.2 $ 1,871.2 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (1.3 ) $ — $ (1.3 ) Total liabilities measured at fair value $ — $ (1.3 ) $ — $ (1.3 ) Total assets measured at fair value, reported as: Cash equivalents $ — $ 3.4 $ — $ 3.4 Restricted investments 35.9 — — 35.9 Short-term investments 108.2 418.9 — 527.1 Long-term investments 165.6 1,078.6 — 1,244.2 Prepaid expenses and other current assets — 0.4 — 0.4 Other long-term assets — — 60.2 60.2 Total assets measured at fair value $ 309.7 $ 1,501.3 $ 60.2 $ 1,871.2 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (1.3 ) $ — $ (1.3 ) Total liabilities measured at fair value $ — $ (1.3 ) $ — $ (1.3 ) ________________________________ (1) Balance includes $29.7 million of restricted investments measured at fair market value, related to the Company's D&O trust and acquisitions related escrows. (2) Balance relates to the restricted investments measured at fair market value of the Company's India Gratuity Trust. (3) Balance relates to the investments measured at fair value related to the Company's non-qualified deferred compensation plan assets. Fair Value Measurements at December 31, 2014 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 $ — $ 269.0 $ — $ 269.0 Certificates of deposit — 10.6 — 10.6 Commercial paper — 20.3 — 20.3 Corporate debt securities — 738.0 — 738.0 Foreign government debt securities — 24.6 — 24.6 Government-sponsored enterprise obligations — 162.1 — 162.1 Money market funds (1) 594.2 — — 594.2 Mutual funds (2) 4.0 — — 4.0 Publicly-traded equity securities 2.0 — — 2.0 U.S. government securities 246.0 — — 246.0 Total available-for-sale securities 846.2 1,224.6 — 2,070.8 Trading securities in mutual funds (3) 16.3 — — 16.3 Privately-held debt and redeemable preferred stock securities — — 47.5 47.5 Derivative assets: Foreign exchange contracts — 0.1 — 0.1 Total assets measured at fair value $ 862.5 $ 1,224.7 $ 47.5 $ 2,134.7 Liabilities measured at fair value: Derivative liabilities: Foreign exchange contracts $ — $ (3.9 ) $ — $ (3.9 ) Total liabilities measured at fair value $ — $ (3.9 ) $ — $ (3.9 ) Total assets measured at fair value, reported as: Cash equivalents $ 552.9 $ 23.7 $ — $ 576.6 Restricted investments 45.2 — — 45.2 Short-term investments 87.0 245.2 — 332.2 Long-term investments 177.4 955.7 — 1,133.1 Prepaid expenses and other current assets — 0.1 — 0.1 Other long-term assets — — 47.5 47.5 Total assets measured at fair value $ 862.5 $ 1,224.7 $ 47.5 $ 2,134.7 Total liabilities measured at fair value, reported as: Other accrued liabilities $ — $ (3.9 ) $ — $ (3.9 ) Total liabilities measured at fair value $ — $ (3.9 ) $ — $ (3.9 ) _______________________________ (1) Balance includes $41.3 million of restricted investments measured at fair market value, related to the Company's D&O trust and acquisition related escrows. (2) Balance relates to the restricted investments measured at fair market value of the Company's India Gratuity Trust. (3) Balance relates to the investments measured at fair value related to the Company's non-qualified deferred compensation plan assets.

Derivative Instruments (Tables)

Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments	The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions): As of December 31, 2015 2014 Cash flow hedges $ 116.8 $ 160.7 Non-designated derivatives 71.8 78.0 Total $ 188.6 $ 238.7

Goodwill and Purchased Intang34

Goodwill and Purchased Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	The following table presents the goodwill activity (in millions): Total December 31, 2013 $ 4,057.7 Additions due to business combination 13.6 Impairment (850.0 ) Divestiture (239.8 ) December 31, 2014 2,981.5 Other (0.2 ) December 31, 2015 $ 2,981.3
Purchased Intangible Assets	The Company’s purchased intangible assets were as follows (in millions): Gross Accumulated Amortization Accumulated Impairments and Other Charges Net As of December 31, 2015 Intangible assets with finite lives: Technologies and patents $ 567.7 $ (491.8 ) $ (49.9 ) $ 26.0 Customer contracts, support agreements, and related relationships 78.1 (67.8 ) (2.8 ) 7.5 Other 1.1 (0.7 ) — 0.4 Total purchased intangible assets $ 646.9 $ (560.3 ) $ (52.7 ) $ 33.9 As of December 31, 2014 Intangible assets with finite lives: Technologies and patents $ 567.7 $ (466.1 ) $ (49.9 ) $ 51.7 Customer contracts, support agreements, and related relationships 78.1 (65.2 ) (2.8 ) 10.1 Other 1.1 (0.5 ) — 0.6 Total purchased intangible assets $ 646.9 $ (531.8 ) $ (52.7 ) $ 62.4
Schedule of Intangible Assets Amortization Included in Consolidated Statements of Operations	The following table presents the amortization of intangible assets included in the Consolidated Statements of Operations (in millions): Years Ended December 31, 2015 2014 2013 Cost of revenues $ 24.6 $ 30.9 $ 27.3 Operating expenses: Sales and marketing 2.8 4.2 3.4 General and administrative 1.1 1.2 1.2 Total operating expenses 3.9 5.4 4.6 Total $ 28.5 $ 36.3 $ 31.9
Estimated Future Amortization Expense of Purchased Intangible Assets with Finite Lives	As of December 31, 2015 , the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions): Years Ending December 31, Amount 2016 $ 11.6 2017 7.0 2018 5.1 2019 4.9 2020 4.8 Thereafter 0.5 Total $ 33.9

Other Financial Information (Ta

Other Financial Information (Tables)	12 Months Ended
	Dec. 31, 2015
Other Financial Information [Abstract]
Inventories	Total inventories consisted of the following (in millions): As of December 31, 2015 2014 Production materials $ 61.9 $ 38.3 Finished goods 13.1 24.2 Inventories $ 75.0 $ 62.5
Property and equipment	Property and equipment, net, consisted of the following (in millions): As of December 31, 2015 2014 Computers and equipment $ 915.1 $ 806.1 Software 169.1 161.2 Leasehold improvements 203.4 179.5 Furniture and fixtures 43.2 33.7 Building and building improvements 246.1 238.4 Land and land improvements 241.1 241.0 Construction-in-process (1) 158.2 70.3 Property and equipment, gross 1,976.2 1,730.2 Accumulated depreciation (955.2 ) (825.9 ) Property and equipment, net $ 1,021.0 $ 904.3 _______________________________ (1) On July 10, 2015, the Company entered into a data center lease agreement that was accounted for as a build-to-suit lease. As the Company was deemed to be the owner of the property during the construction period, the Company capitalized the construction cost in property, plant and equipment and recorded a corresponding financing liability of $45.6 million on the Consolidated Balance Sheet as of December 31, 2015.
Other long-term assets	Other long-term assets consisted of the following (in millions): As of December 31, 2015 2014 Privately-held investments $ 102.4 $ 89.9 Licensed software 7.1 8.6 Federal income tax receivable 28.9 20.0 Customer financing receivable — 16.9 Inventory 8.4 8.0 Prepaid costs, deposits, and other (1) 110.5 75.1 Promissory note, including principal and accrued interest, in connection with the sale of Junos Pulse 132.9 125.0 Other long-term assets (1) $ 390.2 $ 343.5 _______________________________ (1) During the year ended December 31, 2015, the Company early adopted ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the Consolidated Balance Sheets. Certain amounts in the prior-year Consolidated Financial Statements were retrospectively adjusted to conform to the current-year presentation.
Warranties	Changes in the Company’s warranty reserve were as follows (in millions): As of December 31, 2015 2014 Beginning balance $ 28.7 $ 28.0 Provisions made during the period, net 27.9 28.6 Actual costs incurred during the period (28.2 ) (27.9 ) Ending balance $ 28.4 $ 28.7
Deferred revenue	Details of the Company's deferred revenue, as reported in the Consolidated Balance Sheets, were as follows (in millions): As of December 31, 2015 2014 Deferred product revenue: Undelivered product commitments and other product deferrals $ 210.1 $ 180.3 Distributor inventory and other sell-through items 81.8 103.7 Deferred gross product revenue 291.9 284.0 Deferred cost of product revenue (51.6 ) (58.4 ) Deferred product revenue, net 240.3 225.6 Deferred service revenue 927.8 850.1 Total $ 1,168.1 $ 1,075.7 Reported as: Current $ 822.9 $ 780.8 Long-term 345.2 294.9 Total $ 1,168.1 $ 1,075.7
Other (expense) income, net	Other (expense) income, net consisted of the following (in millions): Years Ended December 31, 2015 2014 2013 Interest income $ 21.8 $ 10.0 $ 8.7 Interest expense (83.3 ) (66.9 ) (58.4 ) Net gain on legal settlement — 196.1 — Gain on investments 6.8 167.9 11.3 Gain on sale of Junos Pulse — 19.6 — Other (5.1 ) 6.7 (2.0 ) Other (expense) income, net $ (59.8 ) $ 333.4 $ (40.4 )

Restructuring and Other Charg36

Restructuring and Other Charges (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Summary of restructuring charges	The following table presents restructuring and other charges and (benefits) included in cost of revenues and restructuring and other (benefits) charges in the Consolidated Statements of Operations under the Company's restructuring plans (in millions): Years Ended December 31, 2015 2014 2013 Severance $ 0.4 $ 52.6 $ 22.9 Facilities (1.0 ) 14.4 10.0 Contract terminations and other — 2.3 14.6 Asset impairments and write-downs (3.5 ) 139.2 — Total $ (4.1 ) $ 208.5 $ 47.5 Reported as: Cost of revenues $ (3.5 ) $ 41.5 $ 8.4 Restructuring and other (benefits) charges (0.6 ) 167.0 39.1 Total $ (4.1 ) $ 208.5 $ 47.5
Changes in the restructuring liability	The following table provides a summary of changes in the restructuring liability related to the Company's plans during the year ended December 31, 2015 (in millions): December 31, Charges Cash Payments Non-cash Settlements and Other December 31, Severance $ 9.4 $ 0.4 $ (8.2 ) $ (1.6 ) $ — Facilities 7.4 (1.0 ) (2.3 ) (1.3 ) 2.8 Contract terminations and other 0.2 (3.5 ) — 3.3 — Total $ 17.0 $ (4.1 ) $ (10.5 ) $ 0.4 $ 2.8

Debt and Financing (Tables)

Debt and Financing (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Instruments [Abstract]
Long-term Debt	The following table summarizes the Company's short-term and long-term debt (in millions, except percentages): As of December 31, 2015 Amount Effective Interest Rates Senior notes: 3.10% fixed-rate notes, due March 2016 $ 300.0 3.25 % 3.30% fixed-rate notes, due June 2020 300.0 3.47 % 4.60% fixed-rate notes, due March 2021 300.0 4.69 % 4.50% fixed-rate notes, due March 2024 350.0 4.63 % 4.35% fixed-rate notes, due June 2025 300.0 4.47 % 5.95% fixed-rate notes, due March 2041 400.0 6.03 % Total senior notes 1,950.0 Unaccreted discount (1.3 ) Total $ 1,948.7 Reported as: Short-term debt $ 299.9 Long-term debt 1,648.8 Total $ 1,948.7

Equity (Tables)

Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Repurchase and Retirement of Common Stock and Net Issuances	The following table summarizes the Company's repurchases and retirements of its common stock under its stock repurchase programs and accelerated share repurchase, and repurchases associated with minimum tax withholdings (in millions, except per share amounts): Shares Repurchased Average price per share Amount Repurchased 2015 Repurchases under stock repurchase program 45.4 $ 25.16 $ 1,142.5 Repurchases for tax withholding 0.4 $ 26.70 $ 11.1 2014 Repurchases under stock repurchase program 46.8 $ 22.42 $ 1,050.0 Accelerated share repurchase (1) 49.3 $ 24.35 $ 1,200.0 Repurchases for tax withholding 0.6 $ 19.69 $ 12.5 2013 Repurchases under stock repurchase program 28.9 $ 19.76 $ 570.6 Repurchases for tax withholding 0.4 $ 20.23 $ 7.2 _______________________________ (1) As part of the 2014 Stock Repurchase Program, the Company entered into two separate accelerated share repurchase agreements (collectively, the "ASR") with two financial institutions to repurchase $1.2 billion of the Company's common stock. The Company made an up-front payment of $1.2 billion pursuant to the ASR to repurchase the Company's common stock. The aggregate number of shares ultimately purchased was determined based on a volume weighted average repurchase price, less an agreed upon discount. The shares received with respect to the ASR have been retired. Retired shares return to authorized but unissued shares of common stock.
Schedule of Accumulated Other Comprehensive Income (Loss)	The components of accumulated other comprehensive loss, net of related taxes, for the years ended December 31, 2015 and December 31, 2014 were as follows (in millions): Unrealized Gains (Losses) on Available-for- Sale Securities (1) Unrealized Gains (Losses) on Cash Flow Hedges (2) Foreign Currency Translation Adjustments Total Balance as of December 31, 2013 $ 66.2 $ 2.2 $ (3.8 ) $ 64.6 Other comprehensive gain (loss) before reclassifications 48.7 (4.1 ) (14.2 ) 30.4 Amount reclassified from accumulated other comprehensive income (106.5 ) (2.3 ) — (108.8 ) Other comprehensive loss (57.8 ) (6.4 ) (14.2 ) (78.4 ) Balance as of December 31, 2014 $ 8.4 $ (4.2 ) $ (18.0 ) $ (13.8 ) Other comprehensive gain (loss) before reclassifications 9.1 (6.7 ) (16.9 ) (14.5 ) Amount reclassified from accumulated other comprehensive income (0.5 ) 9.6 — 9.1 Other comprehensive gain (loss), net 8.6 2.9 (16.9 ) (5.4 ) Balance as of December 31, 2015 $ 17.0 $ (1.3 ) $ (34.9 ) $ (19.2 ) ________________________________ (1) The reclassifications out of accumulated other comprehensive income, net of tax during the years ended December 31, 2015 and December 31, 2014 for realized gains on available-for-sale securities of $0.5 million and $104.3 million , respectively, are included in other (expense) income, net, in the Consolidated Statements of Operations. (2) The reclassifications out of accumulated other comprehensive (loss) income, net of tax during the year ended December 31, 2015 for realized losses on cash flow hedges are included within cost of revenues of $2.9 million , research and development of $0.2 million , sales and marketing of $6.0 million , and general and administrative of $0.5 million in the Consolidated Statements of Operations. The reclassifications out of accumulated other comprehensive income during the year ended December 31, 2014 for realized gains on cash flow hedges are included within research and development of $1.4 million , sales and marketing of $0.3 million , and general and administrative of $0.7 million and for realized losses within cost of revenues of $0.1 million for which the hedged transactions relate in the Consolidated Statements of Operations.

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2015
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 years ended December 31, 2015 (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, 2012 34.1 $ 24.13 3.1 $ 52.5 Canceled (1.3 ) 29.56 Exercised (5.6 ) 15.58 Expired (4.1 ) 28.35 Balance as of December 31, 2013 23.1 $ 25.15 2.4 $ 44.6 Canceled (0.6 ) 30.15 Exercised (5.4 ) 19.76 Expired (7.2 ) 29.11 Balance as of December 31, 2014 9.9 $ 24.87 2.0 $ 24.7 Canceled (0.1 ) 23.65 Exercised (3.5 ) 19.78 Expired (2.7 ) 27.99 Balance as of December 31, 2015 3.6 $ 27.52 2.1 $ 16.6 As of December 31, 2015: Vested and expected-to-vest options 3.6 $ 27.58 2.1 $ 16.3 Exercisable options 3.4 $ 28.82 1.8 $ 12.1
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	The following table summarizes additional information regarding outstanding and exercisable options as of December 31, 2015 : Options Outstanding Options Exercisable Range of Exercise Price (In dollars) Number Outstanding (In millions) Weighted Average Remaining Contractual Life (In years) Weighted Average Exercise Price (In dollars) Number Exercisable (In millions) Weighted Average Exercise Price (In dollars) $0.03 - $14.68 0.4 5.3 $ 3.38 0.3 $ 4.94 $15.09 - $18.45 0.4 0.7 15.58 0.3 15.47 $18.49 - $26.10 0.4 2.3 24.11 0.3 24.19 $26.39 - $27.44 0.5 1.0 26.97 0.5 26.97 $27.62 - $29.33 0.1 2.0 28.88 0.1 28.88 $29.89 - $29.89 0.5 1.2 29.89 0.5 29.89 $30.01 - $36.49 0.4 1.9 32.76 0.4 32.76 $38.93 - $38.93 0.1 2.4 38.93 0.1 38.93 $40.26 - $40.26 0.5 2.2 40.26 0.6 40.26 $44.00 - $44.00 0.3 2.1 44.00 0.3 44.00 $0.03 - $44.00 3.6 2.1 $ 27.52 3.4 $ 28.82
Schedule of Nonvested Share Activity	The following table summarizes the Company’s RSU, RSA, and PSA activity and related information as of and for the three years ended December 31, 2015 (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, 2012 26.8 $ 27.76 1.7 $ 565.0 RSUs granted 10.3 20.32 PSAs granted (1) 2.2 21.27 RSUs vested (2) (6.1 ) 26.15 PSAs vested (2) (1.1 ) 28.52 RSAs vested (2) (1.6 ) 19.59 RSUs canceled (3.4 ) 22.99 PSAs canceled (1.7 ) 29.10 Balance as of December 31, 2013 25.4 $ 23.44 1.1 $ 573.5 RSUs granted (3)(6) 10.0 22.52 RSUs assumed (4) 0.4 22.66 RSAs assumed (4) 0.9 22.66 PSAs granted (5)(6) 1.4 24.25 PSAs assumed (4) 0.2 22.66 RSUs vested (2) (7.3 ) 22.98 RSAs vested (2) (1.4 ) 19.59 PSAs vested (2) (1.1 ) 36.19 RSUs canceled (4.0 ) 21.63 PSAs canceled (3.2 ) 30.43 Balance as of December 31, 2014 21.3 $ 22.05 1.1 $ 475.0 RSUs granted (3)(6) 8.9 23.41 PSAs granted (6)(7) 1.0 23.76 RSUs vested (2) (7.2 ) 22.58 RSAs vested (2) (1.8 ) 20.13 PSAs vested (2) (0.3 ) 22.52 RSUs canceled (2.3 ) 22.18 PSAs canceled (1.0 ) 22.27 Balance at December 31, 2015 18.6 $ 22.71 1.1 $ 514.1 As of December 31, 2015 Vested and expected-to-vest RSUs, RSAs, and PSAs 15.3 $ 22.59 1.0 $ 421.3 ________________________________ (1) 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 (or an authorized subcommittee) are achieved at target is 1.1 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 2.2 million shares. (2) Total fair value of RSUs, RSAs, and PSAs vested during 2015 , 2014 , and 2013 was $202.7 million , $238.5 million , and $221.5 million , respectively. (3) Includes service-based and market-based RSUs granted under the 2006 Plan and 2015 Plan according to their terms. (4) RSUs, RSAs, and PSAs assumed in connection with the acquisition of WANDL Inc. (5) 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 (or an authorized subcommittee) are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 1.4 million shares. (6) On February 20, 2014, the Company announced its intention to initiate a quarterly cash dividend of $0.10 per share of common stock in the third quarter of 2014. As a result of the Company's announcement, the grant date fair value of RSUs and PSAs granted after the announcement date were reduced by the present value of the dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested. (7) 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 (or an authorized subcommittee) are achieved at target is 0.7 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 1.0 million shares.
Shares available for grant	The following table presents the stock activity and the total number of shares available for grant under the 2015 Plan and the 2006 Plan, as applicable: Number of Shares Balance as of December 31, 2014 47.8 RSUs and PSAs granted (1) (20.7 ) RSUs and PSAs canceled (1)(2) 7.0 Options canceled (2) 0.1 Options expired (2) 2.7 Shares discontinued (3) (38.2 ) Shares authorized under the 2015 Plan 38.0 Balance as of December 31, 2015 36.7 ________________________________ (1) RSUs and PSAs with a per share or unit purchase price lower than 100% of the fair market value of the Company's common stock on the day of the grant under the 2015 Plan and the 2006 Plan are counted against shares authorized under the plan as two and one-tenth shares of common stock for each share subject to such award. The number of shares subject to PSAs granted represents the maximum number of shares that may be issued pursuant to the award over its full term. (2) Canceled or expired options under the 2006 Plan and the 1996 Plan and canceled RSUs and PSAs under the 2006 Plan are no longer available for future grant under such plans; however, the number of shares available for grant under the 2015 Plan will be increased by the amount of such canceled or expired options, RSUs or PSAs, as applicable, up to a maximum of 29.0 million additional shares of common stock, pursuant to the terms of the 2015 Plan. (3) Authorized shares not subject to outstanding awards under the 2006 Plan were canceled on May 19, 2015, following the approval by the Company’s stockholders of the 2015 Plan. Effective May 19, 2015, no additional awards are issuable under the 2006 Plan.
Schedule Of Share-based Payment Award, Stock Options and Employee Stock Purchase Plan, Valuation Assumptions	The weighted-average assumptions used and the resulting estimates of fair value for stock options, ESPP, and market-based RSUs were as follows: Years Ended December 31, 2015 2014 2013 ESPP (1) : Volatility 29% 30% 36% Risk-free interest rate 0.1% 0.1% 0.1% Expected life (years) 0.5 0.5 0.5 Dividend yield 1.7% 0% - 1.8% — Weighted-average fair value per share $5.63 $5.72 $5.54 Market-based RSUs (2) Volatility 34% 36% — Risk-free interest rate 1.4% 1.6% — Dividend yield 1.8% 0% - 2.0% — Weighted-average fair value per share $14.97 $16.89 — ________________________________ (1) The Black-Scholes-Merton option-pricing model is utilized to estimate the fair value of ESPP. (2) The fair value of market-based RSUs utilizes the Monte Carlo simulation option pricing model. The Company amortizes the fair value of these awards over the derived service period adjusted for estimated forfeitures for each separately vesting tranche of the award. Provided that the derived service is rendered, the total fair value of the market-based RSUs at the date of grant is recognized as compensation expense even if the market condition is not achieved. However, the number of shares that ultimately vest can vary significantly with the performance of the specified market criteria.
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	Share-based compensation expense associated with stock options, RSUs, RSAs, PSAs, and ESPP was recorded in the following cost and expense categories in the Company's Consolidated Statements of Operations (in millions): Years Ended December 31, 2015 2014 2013 Cost of revenues - Product $ 5.6 $ 5.0 $ 4.7 Cost of revenues - Service 13.8 14.2 15.4 Research and development 125.4 134.5 127.6 Sales and marketing 45.6 60.2 70.9 General and administrative 26.9 26.1 26.0 Total $ 217.3 $ 240.0 $ 244.6
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table summarizes share-based compensation expense by award type (in millions): Years Ended December 31, 2015 2014 2013 Stock options $ 6.6 $ 14.9 $ 31.5 RSUs, RSAs, and PSAs 197.3 209.7 196.8 ESPP 13.4 15.4 16.3 Total $ 217.3 $ 240.0 $ 244.6
Schedule of Unrecognized Compensation Cost, Nonvested Awards	The following table presents unrecognized compensation cost, adjusted for estimated forfeitures, recognized over a weighted-average period related to unvested stock options, RSUs, RSAs, and PSAs as of December 31, 2015 (in millions, except years): Unrecognized Weighted Average Stock options $ 2.1 0.6 RSUs, RSAs, and PSAs $ 211.2 1.7

Segments (Tables)

Segments (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Net revenues by product and service	The following table presents net revenues by product and service (in millions): Years Ended December 31, 2015 2014 2013 Routing $ 2,359.2 $ 2,223.9 $ 2,318.0 Switching 768.3 721.2 638.0 Security 435.6 463.6 563.9 Total product 3,563.1 3,408.7 3,519.9 Total service 1,294.7 1,218.4 1,149.2 Total $ 4,857.8 $ 4,627.1 $ 4,669.1
Net revenues by geographic region	The Company attributes revenues to geographic region based on the customer’s ship-to location. The following table presents net revenues by geographic region (in millions): Years Ended December 31, 2015 2014 2013 Americas: United States $ 2,568.6 $ 2,410.6 $ 2,381.5 Other 223.6 219.7 232.0 Total Americas 2,792.2 2,630.3 2,613.5 Europe, Middle East, and Africa 1,320.3 1,263.3 1,256.9 Asia Pacific 745.3 733.5 798.7 Total $ 4,857.8 $ 4,627.1 $ 4,669.1
Property and equipment, net by geographic region	The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions): As of December 31, 2015 2014 United States $ 925.5 $ 871.7 International 129.4 95.0 Property and equipment, net and purchased intangible assets, net $ 1,054.9 $ 966.7

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Components of income before the provision for income taxes and noncontrolling interest	The components of pretax (loss) income and noncontrolling interest are summarized as follows (in millions): Years Ended December 31, 2015 2014 2013 Domestic $ 456.3 $ (509.7 ) $ 248.7 Foreign 395.9 423.4 276.8 Total pretax (loss) income $ 852.2 $ (86.3 ) $ 525.5
Schedule of Components of Provision for Income Taxes	The provision for income taxes is summarized as follows (in millions): Years Ended December 31, 2015 2014 2013 Current provision (benefit): Federal $ 181.4 $ 180.1 $ (12.9 ) States 15.9 15.2 (5.0 ) Foreign 43.3 33.7 32.5 Total current provision (benefit) 240.6 229.0 14.6 Deferred provision (benefit): Federal (16.7 ) 17.3 51.2 States (0.4 ) 1.2 (2.7 ) Foreign (5.0 ) 0.5 22.6 Total deferred provision (benefit) (22.1 ) 19.0 71.1 Income tax benefits attributable to employee stock plan activity — — — Total provision (benefit) for income taxes $ 218.5 $ 248.0 $ 85.7
Schedule of Effective Income Tax Rate Reconciliation	The provision for income taxes differs from the amount computed by applying the federal statutory rate to pretax (loss) income as follows (in millions): Years Ended December 31, 2015 2014 2013 Expected (benefit) provision at 35% rate $ 298.3 $ (30.2 ) $ 184.0 State taxes (benefit), net of federal benefit 8.9 9.5 (3.6 ) Foreign income at different tax rates (68.9 ) (90.2 ) (37.7 ) R&D tax credits (12.7 ) (17.1 ) (32.5 ) Share-based compensation 13.2 25.3 25.6 Non-deductible goodwill impairment — 297.5 — Gain on sale of Junos Pulse — 75.6 — Release of valuation allowance — (22.8 ) — Settlement with tax authorities — — (28.3 ) Domestic production activities (15.1 ) (6.8 ) (26.3 ) Non-deductible compensation 3.7 3.2 1.5 Cost sharing adjustment (13.2 ) — — Other 4.3 4.0 3.0 Total provision for income taxes $ 218.5 $ 248.0 $ 85.7
Schedule of Deferred Tax Assets and Liabilities	Significant components of the Company's long-term deferred tax assets and deferred tax liabilities are as follows (in millions): As of December 31, 2015 2014 Deferred tax assets: Net operating loss carry-forwards $ 1.0 $ 1.3 Foreign tax credit carry-forwards 75.4 69.7 Research and other credit carry-forwards 128.7 122.5 Deferred revenue 109.3 104.9 Stock-based compensation 49.1 55.8 Cost sharing adjustment 70.1 — Reserves and accruals not currently deductible 173.9 129.8 Other 19.2 19.8 Total deferred tax assets 626.7 503.8 Valuation allowance (146.2 ) (144.5 ) Deferred tax assets, net of valuation allowance 480.5 359.3 Deferred tax liabilities: Property and equipment basis differences (44.1 ) (35.6 ) Purchased intangibles (3.1 ) (16.7 ) Unremitted foreign earnings (365.4 ) (260.6 ) Deferred compensation and other (12.0 ) (5.1 ) Other — — Total deferred tax liabilities (424.6 ) (318.0 ) Net deferred tax assets (1) $ 55.9 $ 41.3 _______________________________ (1) During the year ended December 31, 2015, the Company early adopted ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes, requiring all deferred tax assets and liabilities, and any related valuation allowance, to be classified as non-current on the Consolidated Balance Sheets. Certain amounts in the prior-year Consolidated Financial Statements were retrospectively adjusted to conform to the current-year presentation.
Reconciliation of Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows (in millions): Years Ended December 31, 2015 2014 2013 Balance at beginning of year $ 199.2 $ 137.6 $ 136.1 Tax positions related to current year: Additions 18.1 62.5 15.8 Tax positions related to prior years: Additions 5.3 0.6 22.6 Reductions (2.9 ) — (2.2 ) Settlements — — (31.1 ) Lapses in statutes of limitations (3.6 ) (1.5 ) (3.6 ) Balance at end of year $ 216.1 $ 199.2 $ 137.6

Net Income per Share (Tables)

Net Income per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Calculation of Basic and Diluted Net Income (Loss) Per Share	The Company computed basic and diluted net (loss) income per share attributable to Juniper Networks common stockholders as follows (in millions, except per share amounts): Years Ended December 31, 2015 2014 2013 Numerator: Net income (loss) $ 633.7 $ (334.3 ) $ 439.8 Denominator: Weighted-average shares used to compute basic net income (loss) per share 390.6 457.4 501.8 Dilutive effect of employee stock awards 8.8 — 8.5 Weighted-average shares used to compute diluted net income (loss) per share 399.4 457.4 510.3 Net income (loss) per share attributable to Juniper Networks common stockholders: Basic $ 1.62 $ (0.73 ) $ 0.88 Diluted $ 1.59 $ (0.73 ) $ 0.86 Anti-dilutive: Potential anti-dilutive shares 3.4 20.8 13.2

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The following table summarizes the Company’s future minimum payments under non-cancelable operating leases for each of the next five years and thereafter as of December 31, 2015 (in millions): Years Ending December 31, Amount 2016 $ 35.7 2017 25.6 2018 18.6 2019 10.3 2020 7.8 Thereafter 15.7 Total $ 113.7

Selected Quarterly Financial 44

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Selected Quarterly Financial Information [Abstract]
Schedule of Selected Quarterly Financial Data (Unaudited)	The tables below set forth selected unaudited financial data for each quarter of the two years ended December 31, 2015 (in millions, except per share amounts): Year Ended December 31, 2015 First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues: Product $ 764.1 $ 899.7 $ 925.4 $ 973.9 Service 303.3 322.5 323.2 345.7 Total net revenues 1,067.4 1,222.2 1,248.6 1,319.6 Cost of revenues: Product 288.8 311.7 322.6 346.5 Service 121.3 129.0 128.6 130.7 Total cost of revenues 410.1 440.7 451.2 477.2 Gross margin 657.3 781.5 797.4 842.4 Operating expenses: Research and development 248.7 251.6 247.0 247.2 Sales and marketing 220.2 232.4 235.3 255.9 General and administrative 55.2 56.3 57.1 60.3 Restructuring and other charges (benefit) 1.4 (1.9 ) — (0.1 ) Total operating expenses 525.5 538.4 539.4 563.3 Operating income 131.8 243.1 258.0 279.1 Other expense, net (1)(3) (15.8 ) (17.1 ) (8.4 ) (18.5 ) Income before income taxes 116.0 226.0 249.6 260.6 Income tax provision (2) 35.8 68.0 51.9 62.8 Net income $ 80.2 $ 158.0 $ 197.7 $ 197.8 Net income per share: (4) Basic $ 0.20 $ 0.41 $ 0.52 $ 0.52 Diluted $ 0.19 $ 0.40 $ 0.51 $ 0.51 Cash dividends declared per common stock (5) $ 0.10 $ 0.10 $ 0.10 $ 0.10 _______________________________ (1) During the first quarter of 2015, the Company issued $300.0 million aggregate principal amount of 3.30% senior notes due 2020 and $300.0 million aggregate principal amount of 4.35% senior notes due 2025. As a result, the Company recorded interest expense of $19.1 million , related to long-term debt issued in 2015 in other expense, net during the year ended December 31, 2015 . (2) Includes approximately $13.2 million net benefit of cumulative adjustment related to the change in treatment of share-based compensation as a result of the U.S. Tax Court decision in Altera Corporation et al., or Altera, v. Commissioner. See Note 14, Income Taxes, in Notes to the Consolidated Financial Statements in Item 8 of Part II of this Report for further information. (3) During the fourth quarter of 2015, the Company recorded a gain on privately held investments of $7.3 million in other expense, net. (4) Net income per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period. (5) On January 27, 2015, April 23, 2015, July 23, 2015 and on October 22, 2015, the company declared a quarterly cash dividend of $0.10 per share of common stock to stockholders on record as of the close of business March 3, 2015, June 2, 2015, September 1, 2015, and December 1, 2015, respectively. Year Ended December 31, 2014 First Quarter Second Quarter Third Quarter Fourth Quarter Net revenues: Product $ 876.0 $ 929.2 $ 809.5 $ 794.0 Service 294.1 300.3 316.4 307.6 Total net revenues 1,170.1 1,229.5 1,125.9 1,101.6 Cost of revenues: Product 326.6 359.3 290.0 310.9 Service 123.4 122.0 121.1 115.6 Total cost of revenues (1) 450.0 481.3 411.1 426.5 Gross margin 720.1 748.2 714.8 675.1 Operating expenses: Research and development 264.0 255.5 253.2 233.5 Sales and marketing 273.4 258.0 249.2 243.0 General and administrative 74.9 60.6 55.0 40.6 Restructuring and other charges (benefits) (1) 114.0 58.2 (15.0 ) 9.8 Impairment of goodwill (2) — — — 850.0 Total operating expenses 726.3 632.3 542.4 1,376.9 Operating (loss) income (6.2 ) 115.9 172.4 (701.8 ) Other income (expense), net (3) 154.2 178.6 (6.8 ) 7.4 Income (loss) before income taxes 148.0 294.5 165.6 (694.4 ) Income tax provision 37.4 73.4 62.0 75.2 Net income (loss) $ 110.6 $ 221.1 $ 103.6 $ (769.6 ) Net income (loss) per share: (4) Basic $ 0.23 $ 0.47 $ 0.23 $ (1.81 ) Diluted $ 0.22 $ 0.46 $ 0.23 $ (1.81 ) Cash dividends declared per common stock (5) $ — $ — $ 0.10 $ 0.10 _______________________________ (1) In the first quarter of 2014, the company initiated a 2014 Restructuring Plan, which consisted of $84.7 million asset write-downs, $28.0 million of severance costs, and $0.8 million of contract terminations that were recorded in restructuring and other charges. In addition, the Company recorded inventory write-downs related to the acceleration of the end-of-service life of certain products totaling $8.4 million to cost of revenues. In the second quarter, the Company recorded $9.9 million of severance costs, $37.6 million of facility consolidation and closures, $8.9 million of asset write-downs, and $1.5 million of contract terminations that were recorded to restructuring and other charges. The Company also recorded inventory write-downs of $11.5 million and a charge related to products with contract manufacturers of $2.3 million for acceleration of the end-of-life service of certain products to cost of revenues. In the third quarter, the Company recorded $7.1 million of severance costs, a benefit of $25.0 million of facility consolidation and closures as a result of a lease assignment, and $2.9 million of asset write-downs, that were recorded to restructuring and other (credit) charges. In the fourth quarter, the Company recorded $6.9 million in severance costs, $1.6 million of facility consolidation and closures, and $20.6 million in asset impairment and write-downs. (2) During the fourth quarter of 2014, the Company recorded an $850.0 million goodwill impairment charge related to its Security reporting unit. (3) In the first quarter of 2014, the Company recorded a gain of $163.0 million related to the sale of investments which were converted from privately-held investments to publicly-traded equity upon initial public offering. In the second quarter, the Company entered into a settlement agreement with Palo Alto Networks, which resulted in a realized gain on legal settlement of $195.3 million , net of legal fees. All such Palo Alto Networks securities were sold in the third quarter, and the Company recorded an additional $0.8 million gain. In the fourth quarter, the Company recorded a gain of $19.6 million on the sale of Junos Pulse. (4) Net income (loss) per share is computed independently. Therefore, the sum of the quarterly net income per share may not equal the total computed for the year or any cumulative interim period. (5) On July 22, 2014 and October 23, 2014 the company declared a quarterly cash dividend of $0.10 per share of common stock to stockholders on record as of the close of business September 2, 2014 and December 2, 2014, respectively.

Description of Business and B45

Description of Business and Basis of Presentation (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease in other long-term liabilities	$ (61.6)	$ (27.5)
New Accounting Pronouncement, Early Adoption, Effect
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease in current deferred tax assets	261	147
Decrease in other long-term liabilities	$ 207	$ 107.4

Significant Accounting Polici46

Significant Accounting Policies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)Customer	Dec. 31, 2014USD ($)Customer	Dec. 31, 2013USD ($)Customer	Mar. 31, 2016USD ($)
Significant Accounting Policies [Line Items]
Maturity of highly liquid investments	3 months
Maturity period of cash flow hedge derivatives	1 year
Maturity period of non designated hedges derivatives	1 year
Contractual period	1 year
Warranty period for hardware products (in years)	1 year
Warranty period for software (in days)	90 days
Advertising expense	$ 20.2	$ 19.2	$ 20.1
More than likely percentage of being realized upon settlement, tax benefit	50.00%
Liability for unrecognized tax benefits as current	1 year
Reduction in debt liabilities due to ASU No. 2015-03	$ (1,948.7)
Accounting Standards Update 2015-03 [Member] | Scenario, Forecast [Member]
Significant Accounting Policies [Line Items]
Reduction in unamortized debt issuance expense due to ASU No. 2015-03				$ 11
Reduction in debt liabilities due to ASU No. 2015-03				$ 11
Sales Revenue, Segment [Member] | Customer Concentration Risk [Member]
Significant Accounting Policies [Line Items]
Number of customers accounting for more than 10% of revenues | Customer	0	0	0
Minimum [Member]
Significant Accounting Policies [Line Items]
Contractual support period	1 year
Maximum [Member]
Significant Accounting Policies [Line Items]
Contractual support period	3 years
Computer, Equipment and Software [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	3 years
Computer, Equipment and Software [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	7 years
Furniture and fixtures [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	5 years
Furniture and fixtures [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	7 years
Building and Building Improvements [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	7 years
Building and Building Improvements [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	40 years
Land Improvements [Member] | Minimum [Member]
Significant Accounting Policies [Line Items]
Useful life	5 years
Land Improvements [Member] | Maximum [Member]
Significant Accounting Policies [Line Items]
Useful life	40 years
Leasehold Improvements [Member]
Significant Accounting Policies [Line Items]
Useful life	10 years

Business Combinations, Textuals

Business Combinations, Textuals (Details) $ in Millions	Jan. 07, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)business	Dec. 31, 2013USD ($)business
Business Acquisition [Line Items]
Length of time subsequent to acquisition date may result in changes of additional information		12 months
Number of businesses acquired | business			1	1
2014 Acquisitions [Member]
Business Acquisition [Line Items]
Consideration transferred			$ 28.7
Net tangible assets acquired			0
Intangible assets acquired			$ 17.8
2013 Acquisitions [Member]
Business Acquisition [Line Items]
Consideration transferred				$ 10
Net tangible assets acquired				0.1
Intangible assets acquired				$ 9.9
Acquired intangible asset, weighted average estimated useful life (in years)				5 years
WANDL, Inc, [Member]
Business Acquisition [Line Items]
Intangible assets acquired		$ 17.8
Acquired intangible asset, weighted average estimated useful life (in years)		7 years
WANDL, Inc, [Member] | 2014 Acquisitions [Member]
Business Acquisition [Line Items]
Consideration transferred	$ 28.7
Percentage of interests acquired	100.00%
Share-based awards assumed, fair value	$ 34.9

Business Combinations, Purchase

Business Combinations, Purchase Price Allocation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 2,981.5	$ 4,057.7	$ 2,981.3
2014 Acquisitions [Member]
Business Acquisition [Line Items]
Net tangible assets acquired	0
Net tangible liabilities acquired	(2.7)
Intangible assets acquired	17.8
Goodwill	13.6
Consideration transferred	$ 28.7
2013 Acquisitions [Member]
Business Acquisition [Line Items]
Net tangible assets acquired		0.1
Net tangible liabilities acquired		0
Intangible assets acquired		9.9
Goodwill		0
Consideration transferred		$ 10

Business Combinations, Intangib

Business Combinations, Intangible Assets Acquired (Details) - WANDL, Inc, [Member] $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	7 years
Intangible assets acquired	$ 17.8
Existing technology [Member]
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	7 years
Intangible assets acquired	$ 10.7
Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	7 years
Intangible assets acquired	$ 6
Trade Names [Member]
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	4 years
Intangible assets acquired	$ 0.6
Backlog [Member]
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	1 year
Intangible assets acquired	$ 0.2
Non-compete Agreements [Member]
Business Acquisition [Line Items]
Acquired intangible asset, weighted average estimated useful life (in years)	2 years
Intangible assets acquired	$ 0.3

Cash Equivalents and Investme50

Cash Equivalents and Investments - Available for Sale Securities (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Available-for-sale securities, amortized cost	$ 1,796.4	$ 2,071.9
Available-for-sale Securities, gross unrealized gain	1.1	0.6
Available-for-sale securities, gross unrealized loss	(4.6)	(1.7)
Available-for-sale securities, estimated fair value	1,792.9	2,070.8
Trading securities:
Trading securities, amortized cost	17.7	16.3
Trading securities, gross unrealized gain	0	0
Trading securities, gross unrealized loss	0	0
Trading securities, estimated fair value	17.7	16.3
Available-for-sale and Trading Investments [Abstract]
Total investments, amortized cost	1,814.1	2,088.2
Total investments, gross unrealized gains	1.1	0.6
Total investments, gross unrealized losses	(4.6)	(1.7)
Total investments, estimated fair value	1,810.6	2,087.1
Cash equivalents [Member]
Available-for-sale and Trading Investments [Abstract]
Total investments, amortized cost	3.4	576.6
Total investments, gross unrealized gains	0	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	3.4	576.6
Restricted investments [Member]
Available-for-sale and Trading Investments [Abstract]
Total investments, amortized cost	35.8	45.2
Total investments, gross unrealized gains	0.1	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	35.9	45.2
Short-term investments [Member]
Available-for-sale and Trading Investments [Abstract]
Total investments, amortized cost	527.2	332.2
Total investments, gross unrealized gains	0.9	0.2
Total investments, gross unrealized losses	(1)	(0.2)
Total investments, estimated fair value	527.1	332.2
Long-term investments [Member]
Available-for-sale and Trading Investments [Abstract]
Total investments, amortized cost	1,247.7	1,134.2
Total investments, gross unrealized gains	0.1	0.4
Total investments, gross unrealized losses	(3.6)	(1.5)
Total investments, estimated fair value	1,244.2	1,133.1
Fixed Income Securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	1,751.9	1,471.7
Available-for-sale Securities, gross unrealized gain	0.2	0.5
Available-for-sale securities, gross unrealized loss	(3.9)	(1.6)
Available-for-sale securities, estimated fair value	1,748.2	1,470.6
Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	312.2	269.3
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	(0.5)	(0.3)
Available-for-sale securities, estimated fair value	311.7	269
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	9.6	10.6
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	0	0
Available-for-sale securities, estimated fair value	9.6	10.6
Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	17.7	20.3
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	0	0
Available-for-sale securities, estimated fair value	17.7	20.3
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	913.8	738.6
Available-for-sale Securities, gross unrealized gain	0.2	0.5
Available-for-sale securities, gross unrealized loss	(2.6)	(1.1)
Available-for-sale securities, estimated fair value	911.4	738
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	16.5	24.6
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	0	0
Available-for-sale securities, estimated fair value	16.5	24.6
Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	204.1	162.2
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	(0.4)	(0.1)
Available-for-sale securities, estimated fair value	203.7	162.1
US government securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	278	246.1
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	(0.4)	(0.1)
Available-for-sale securities, estimated fair value	277.6	246
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	29.7	594.2
Available-for-sale Securities, gross unrealized gain	0	0
Available-for-sale securities, gross unrealized loss	0	0
Available-for-sale securities, estimated fair value	29.7	594.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	6.1	3.9
Available-for-sale Securities, gross unrealized gain	0.1	0.1
Available-for-sale securities, gross unrealized loss	0	0
Available-for-sale securities, estimated fair value	6.2	4
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	8.7	2.1
Available-for-sale Securities, gross unrealized gain	0.8	0
Available-for-sale securities, gross unrealized loss	(0.7)	(0.1)
Available-for-sale securities, estimated fair value	$ 8.8	$ 2

Cash Equivalents and Investme51

Cash Equivalents and Investments - Maturities of Available for Sale Investments (Details) $ in Millions	Dec. 31, 2015USD ($)
Cash Equivalents and Investments [Abstract]
Amortized cost due within one year	$ 504.1
Gross unrealized gains due within one year	0.1
Gross unrealized losses due within one year	(0.3)
Estimated fair value due within one year	503.9
Amortized cost due between one and five years	1,247.8
Gross unrealized gains due between one and five years	0.1
Gross unrealized losses due between one and five years	(3.6)
Estimated fair value due between one and five year	1,244.3
Total investments, amortized cost	1,751.9
Total investments, gross unrealized gains	0.2
Total investments, gross unrealized losses	(3.9)
Total investments, estimated fair value	$ 1,748.2

Cash Equivalents and Investme52

Cash Equivalents and Investments - Textuals (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)Investment	Dec. 31, 2014USD ($)Investment	Dec. 31, 2013USD ($)
Cash Equivalents and Investments [Abstract]
Total investments In unrealized loss position | Investment	682	437
Other than temporarily impaired		$ 1.1
Available-for-sale securities, gross realized gains		166.8
Privately-held investments	$ 102.4	89.9
Privately held investments at fair value	60.2	47.5
Unrealized gains, privately-held debt securities	$ 11.4
Unrealized gain on privately held investments		15
Other than temporary impairment of privately held equity investments		$ 1.1	$ 2.8

Cash Equivalents and Investme53

Cash Equivalents and Investments - Unrealized Loss for Trading and Available for Sale Investments (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	$ 1,421.6	$ 1,067.2
Unrealized loss, less than 12 months	(4.2)	(1.7)
Fair value, 12 months or greater	89.7	0
Unrealized loss, 12 months or greater	(0.4)	0
Total fair value, Available-for-sale investments in continuous unrealized loss position	1,511.3	1,067.2
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(4.6)	(1.7)
Fixed Income Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	1,419.5	1,065.2
Unrealized loss, less than 12 months	(3.5)	(1.6)
Fair value, 12 months or greater	89.7	0
Unrealized loss, 12 months or greater	(0.4)	0
Total fair value, Available-for-sale investments in continuous unrealized loss position	1,509.2	1,065.2
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(3.9)	(1.6)
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	274.2	221.9
Unrealized loss, less than 12 months	(0.4)	(0.3)
Fair value, 12 months or greater	30.8	0
Unrealized loss, 12 months or greater	(0.1)	0
Total fair value, Available-for-sale investments in continuous unrealized loss position	305	221.9
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(0.5)	(0.3)
Certificates of deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	3.3
Unrealized loss, less than 12 months	0
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	3.3
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	0
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	687.9	515.9
Unrealized loss, less than 12 months	(2.3)	(1.1)
Fair value, 12 months or greater	58.9	0
Unrealized loss, 12 months or greater	(0.3)	0
Total fair value, Available-for-sale investments in continuous unrealized loss position	746.8	515.9
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(2.6)	(1.1)
Foreign government debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	9.5	24.6
Unrealized loss, less than 12 months	0	0
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	9.5	24.6
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	0	0
Government-sponsored enterprise obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	185.3	113.8
Unrealized loss, less than 12 months	(0.4)	(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	185.3	113.8
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(0.4)	(0.1)
US government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	259.3	189
Unrealized loss, less than 12 months	(0.4)	(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	259.3	189
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	(0.4)	(0.1)
Publicly-traded equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	2.1	2
Unrealized loss, less than 12 months	(0.7)	(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	2.1	2
Total unrealized loss, Available-for-sale investments in continuous unrealized loss position	$ (0.7)	$ (0.1)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Available-for-sale securities, estimated fair value	$ 1,792.9	$ 2,070.8
Trading securities:
Trading securities, estimated fair value	17.7	16.3
Fair Value Measurements (Textuals)
Restricted investments	29.7	41.3
Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	311.7	269
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	9.6	10.6
Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	17.7	20.3
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	911.4	738
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	16.5	24.6
Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	203.7	162.1
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	29.7	594.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	6.2	4
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	8.8	2
US Government Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	277.6	246
Debt Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	1,748.2	1,470.6
Fair Value, Measurements, Recurring [Member]
Liabilities measured at fair value:
Other accrued liabilities	(1.3)	(3.9)
Total liabilities measured at fair value	(1.3)	(3.9)
Total assets measured at fair value	1,871.2	2,134.7
Cash equivalents	3.4	576.6
Restricted investments	35.9	45.2
Short-term investments	527.1	332.2
Long-term investments	1,244.2	1,133.1
Prepaid expenses and other current assets	0.4	0.1
Other long-term assets	60.2	47.5
Fair Value, Measurements, Recurring [Member] | Foreign exchange contract [Member]
Derivative assets:
Derivative assets measured at fair value on a recurring basis	0.4	0.1
Liabilities measured at fair value:
Derivative liabilities:	(1.3)	(3.9)
Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	1,792.9	2,070.8
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	311.7	269
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	9.6	10.6
Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	17.7	20.3
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	911.4	738
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	16.5	24.6
Fair Value, Measurements, Recurring [Member] | Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	203.7	162.1
Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	29.7	594.2
Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	6.2	4
Trading securities:
Trading securities, estimated fair value	17.7	16.3
Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	8.8	2
Fair Value, Measurements, Recurring [Member] | US Government Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	277.6	246
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Trading securities:
Privately-held debt securities, estimated fair value	60.2	47.5
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities measured at fair value:
Other accrued liabilities	0	0
Total liabilities measured at fair value	0	0
Total assets measured at fair value	309.7	862.5
Cash equivalents	0	552.9
Restricted investments	35.9	45.2
Short-term investments	108.2	87
Long-term investments	165.6	177.4
Prepaid expenses and other current assets	0	0
Other long-term assets	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign exchange contract [Member]
Derivative assets:
Derivative assets measured at fair value on a recurring basis	0	0
Liabilities measured at fair value:
Derivative liabilities:	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	292	846.2
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	29.7	594.2
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	6.2	4
Trading securities:
Trading securities, estimated fair value	17.7	16.3
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	8.8	2
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	247.3	246
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Trading securities:
Privately-held debt securities, estimated fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities measured at fair value:
Other accrued liabilities	(1.3)	(3.9)
Total liabilities measured at fair value	(1.3)	(3.9)
Total assets measured at fair value	1,501.3	1,224.7
Cash equivalents	3.4	23.7
Restricted investments	0	0
Short-term investments	418.9	245.2
Long-term investments	1,078.6	955.7
Prepaid expenses and other current assets	0.4	0.1
Other long-term assets	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign exchange contract [Member]
Derivative assets:
Derivative assets measured at fair value on a recurring basis	0.4	0.1
Liabilities measured at fair value:
Derivative liabilities:	(1.3)	(3.9)
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	1,500.9	1,224.6
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	311.7	269
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	9.6	10.6
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	17.7	20.3
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	911.4	738
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	16.5	24.6
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	203.7	162.1
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Trading securities:
Trading securities, estimated fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	30.3	0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Trading securities:
Privately-held debt securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities measured at fair value:
Other accrued liabilities	0	0
Total liabilities measured at fair value	0	0
Total assets measured at fair value	60.2	47.5
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	60.2	47.5
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign exchange contract [Member]
Derivative assets:
Derivative assets measured at fair value on a recurring basis	0	0
Liabilities measured at fair value:
Derivative liabilities:	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Available-for-sale Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Trading securities:
Trading securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Securities [Member]
Available-for-sale securities:
Available-for-sale securities, estimated fair value	0	0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Debt Securities [Member]
Trading securities:
Privately-held debt securities, estimated fair value	60.2	$ 47.5
Fair Value Measurements (Textuals)
Purchases of privately-held investments	$ 5.3

Fair Value Measurements, Assets

Fair Value Measurements, Assets and Liabilities Measured On A Nonrecurring Basis (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other than temporary impairment of privately held equity investments						$ 1.1	$ 2.8
Impairment of goodwill	$ (850)	$ 0	$ 0	$ 0	$ 0	(850)	0
Security [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of goodwill	(850)					(850)
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value promissory note					132.9
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	1,395.2				1,946.7	1,395.2
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Liability measured at non-recurring basis	$ 0				$ 0	$ 0	0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cost Method Investment, Privately Held Companies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Privately-held investments measured on nonrecurring basis							2
Other than temporary impairment of privately held equity investments							$ 2.8

Derivative Instruments (Details

Derivative Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	$ 188.6	$ 238.7
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	116.8	160.7
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivative	$ 71.8	$ 78

Derivative Instruments, Cash Fl

Derivative Instruments, Cash Flow Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivatives, Fair Value [Line Items]
Maximum cash flow hedge derivative term	1 year
Foreign exchange contract [Member] | Cash flow hedging [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments recognized in AOCI	$ (6.3)	$ (3.4)	$ (1)
Foreign exchange contract [Member] | Cash flow hedging [Member] | Operating expenses [Member]
Derivatives, Fair Value [Line Items]
Gain (loss) on derivative instruments reclassified out of AOCI	$ (9.6)	$ 3.4	$ 0.7

Derivative Instruments, Non-Des

Derivative Instruments, Non-Designated Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Foreign exchange contract [Member] | Other (expense) income, net [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on non-designated derivatives	$ (0.6)	$ (2.4)	$ 0.9

Goodwill and Purchased Intang59

Goodwill and Purchased Intangible Assets (Details) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)Reportable_Segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Goodwill [Roll Forward]
Goodwill, beginning of period				$ 4,057.7	$ 2,981.5	$ 4,057.7
Additions due to business combination						13.6
Impairment	$ (850)	$ 0	$ 0	$ 0	0	(850)	$ 0
Divestiture						(239.8)
Other					(0.2)
Goodwill, end of period	$ 2,981.5				$ 2,981.3	$ 2,981.5	$ 4,057.7
Number of reporting units | Reportable_Segment					3

Goodwill and Purchased Intang60

Goodwill and Purchased Intangible Assets, Finite Lived Intangible Assets by Class (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Purchased Intangible Assets [Line Items]
Net	$ 33.9
Total purchased intangible assets, gross	646.9	$ 646.9
Total purchased intangible assets, accumulated amortization	(560.3)	(531.8)
Accumulated intangible asset impairment and other charges	(52.7)	(52.7)
Total purchased intangible assets, net	33.9	62.4
Amortization of intangible assets	28.5	36.3	$ 31.9
Acceleration of the end of life of certain intangible assets, finite-lived	5.6
Intangible assets no longer utilized		20
Impairment of intangible assets			0
Cost of revenues [Member]
Purchased Intangible Assets [Line Items]
Amortization of intangible assets	24.6	30.9	27.3
Cost of revenues [Member] | Intangible Asset Write-Down [Member] | Restructuring Plan 2014 [Member]
Purchased Intangible Assets [Line Items]
Impairment of intangible assets		19.3
Selling and marketing [Member]
Purchased Intangible Assets [Line Items]
Amortization of intangible assets	2.8	4.2	3.4
General and administrative [Member]
Purchased Intangible Assets [Line Items]
Amortization of intangible assets	1.1	1.2	1.2
Operating expenses [Member]
Purchased Intangible Assets [Line Items]
Amortization of intangible assets	3.9	5.4	$ 4.6
Restructuring and Other Charges [Member] | Intangible Asset Write-Down [Member] | Restructuring Plan 2014 [Member]
Purchased Intangible Assets [Line Items]
Impairment of intangible assets		0.7
Technologies and patents [Member]
Purchased Intangible Assets [Line Items]
Gross	567.7	567.7
Accumulated amortization	(491.8)	(466.1)
Impairment and other charges	(49.9)	(49.9)
Net	26	51.7
Customer Contracts, Support Agreements, and Related Relationships [Member]
Purchased Intangible Assets [Line Items]
Gross	78.1	78.1
Accumulated amortization	(67.8)	(65.2)
Impairment and other charges	(2.8)	(2.8)
Net	7.5	10.1
Other [Member]
Purchased Intangible Assets [Line Items]
Gross	1.1	1.1
Accumulated amortization	(0.7)	(0.5)
Impairment and other charges	0	0
Net	$ 0.4	$ 0.6

Goodwill and Purchased Intang61

Goodwill and Purchased Intangible Assets, Estimated Future Amortization Expense Intangible Assets (Details) $ in Millions	Dec. 31, 2015USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,016	$ 11.6
2,017	7
2,018	5.1
2,019	4.9
2,020	4.8
Thereafter	0.5
Net	$ 33.9

Other Financial Information, In

Other Financial Information, Inventories (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014
Schedule of Inventory [Line Items]
Production materials		$ 61.9	$ 38.3
Finished goods		13.1	24.2
Total inventories, net		75	62.5
Restructuring charges, inventory write-down		$ (4.1)
Inventory Write-down [Member] | Restructuring Plan 2014 [Member]
Schedule of Inventory [Line Items]
Restructuring charges, inventory write-down	$ 11.5		$ 15.5

Other Financial Information, Pr

Other Financial Information, Property and Equipment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property and Equipment [Line Items]
Property and equipment, gross	$ 1,976.2	$ 1,730.2
Construction-in-process, gross	158.2	70.3
Accumulated depreciation	(955.2)	(825.9)
Property and equipment, net	1,021	904.3
Depreciation expense	141.5	141.9	$ 148.2
Construction in Progress [Member]
Property and Equipment [Line Items]
Property and equipment, net	45.6
Computers and equipment [Member]
Property and Equipment [Line Items]
Property and equipment, gross	915.1	806.1
Software [Member]
Property and Equipment [Line Items]
Property and equipment, gross	169.1	161.2
Leasehold Improvements [Member]
Property and Equipment [Line Items]
Property and equipment, gross	203.4	179.5
Furniture and fixtures [Member]
Property and Equipment [Line Items]
Property and equipment, gross	43.2	33.7
Building and Building Improvements [Member]
Property and Equipment [Line Items]
Property and equipment, gross	246.1	238.4
Land and land improvements [Member]
Property and Equipment [Line Items]
Property and equipment, gross	$ 241.1	$ 241

Other Financial Information, Ot

Other Financial Information, Other Long-Term Assets (Details) - USD ($) $ in Millions	12 Months Ended		18 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Apr. 01, 2017	Oct. 01, 2014
Other Financial Information [Abstract]
Privately-held investments	$ 102.4	$ 89.9
Licensed software	7.1	8.6
Federal income tax receivable	28.9	20
Customer financing receivable	0	16.9
Inventory	8.4	8
Prepaid costs, deposits, and other	110.5	75.1
Other long-term assets	390.2	343.5
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest income	6.3	1.6
Junos Pulse [Member]
Other Financial Information [Abstract]
Promissory note in connection with the sale of Junos Pulse	$ 132.9	$ 125		$ 125
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration				230.7
Cash consideration				105.7
Working capital adjustment				$ 19.3
Scenario, Forecast [Member] | Junos Pulse [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Minimum payment due on or prior to April 1, 2017			$ 75

Other Financial Information, Wa

Other Financial Information, Warranties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Warranty Reserve [Roll Forward]
Beginning balance	$ 28.7	$ 28
Provisions made during the period, net	27.9	28.6
Actual costs incurred during the period	(28.2)	(27.9)
Ending balance	$ 28.4	$ 28.7

Other Financial Information, De

Other Financial Information, Deferred Revenue (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Deferred Revenue [Abstract]
Deferred revenue, net	$ 1,168.1	$ 1,075.7
Deferred Revenue Reported as [Abstract]
Deferred revenue, current	822.9	780.8
Deferred revenue, long-term	345.2	294.9
Deferred product revenue [Member]
Deferred Revenue [Abstract]
Undelivered product commitments and other product deferrals	210.1	180.3
Distributor inventory and other sell-through items	81.8	103.7
Deferred gross product revenue	291.9	284
Deferred cost of product revenue	(51.6)	(58.4)
Deferred revenue, net	240.3	225.6
Deferred service revenue [Member]
Deferred Revenue [Abstract]
Deferred revenue, net	$ 927.8	$ 850.1

Other Financial Information, 67

Other Financial Information, Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 01, 2014
Other Financial Information [Abstract]
Interest income									$ 21.8	$ 10	$ 8.7
Interest expense									(83.3)	(66.9)	(58.4)
Gain on investments									6.8	167.9	11.3
Gain on sale of Junos Pulse									0	19.6	0
Other									(5.1)	6.7	(2)
Other (expense) income, net	$ (18.5)	$ (8.4)	$ (17.1)	$ (15.8)	$ 7.4	$ (6.8)	$ 178.6	$ 154.2	(59.8)	333.4	(40.4)
Interest expense, long-term debt									79.8	57.5	45.2
Capitalized interest									2.2	2.7	1.9
Cost-method investments, realized gains (loss)	7.3								6.8		7.1
Publicly-traded equity and privately-held investments, net realized gain								$ 163		163
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on legal settlement						$ 0.8	$ 195.3		0	196.1	$ 0
Junos Pulse [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration												$ 230.7
Cash consideration												105.7
Working capital adjustment												19.3
Promissory note in connection with the sale of Junos Pulse	$ 132.9				$ 125				$ 132.9	125		$ 125
Palo Alto Networks [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net gain on legal settlement										$ 196.1

Restructuring and Other Charg68

Restructuring and Other Charges - Included in Cost of Revenues and Restructuring and Other Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ (4.1)	$ 208.5	$ 47.5
Cost of Sales [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(3.5)	41.5	8.4
Operating expenses [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(0.6)	167	39.1
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	0.4	52.6	22.9
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	(1)	14.4	10
Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	0	2.3	14.6
Asset impairments and write-down [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges	$ (3.5)	$ 139.2	$ 0

Restructuring and Other Charg69

Restructuring and Other Charges (Details) ft² in Millions, $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2014USD ($)right	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)ft²right	Dec. 31, 2013USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					$ (4.1)	$ 208.5	$ 47.5
Restructuring charges					(4.1)
Area subject to Restructuring Activities | ft²						0.4
Area subject to Sublease | ft²						0.1
Duration of sublease						2 years
Renewal Rights | right	1					1
Duration of renewal period						6 months
Deferred rent liability adjustment						$ 9.8
Impairment of intangible assets							0
Restructuring reserve	$ 17				2.8	17
Cost of revenues [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					(3.5)	41.5	8.4
Restructuring and other charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					(0.6)	167	39.1
Restructuring Plan 2013 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring cost incurred to date	28.9					28.9
Restructuring Plan 2013 [Member] | Cost of revenues [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring cost incurred to date	3.3					3.3
Restructuring Plan 2013 [Member] | Restructuring and other charges [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring cost incurred to date	25.6					25.6
Asset impairments and write-down [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					(3.5)	139.2	0
Asset impairments and write-down [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	20.6	$ 2.9	$ 8.9	$ 84.7		12.3
Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					0.4	52.6	22.9
Restructuring charges					0.4
Restructuring reserve	9.4				0	9.4
Severance [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	6.9	7.1	9.9	28		52
Severance [Member] | Restructuring Plan 2013 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring cost incurred to date							0.6
Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					(1)	14.4	10
Restructuring charges					(1)
Restructuring reserve	7.4				2.8	7.4
Facilities [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1.6	$ 25	37.6			14.2
Amount paid to Landlord						12.3
Transaction Fees						5.3
Impairment charges related to licensed software [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges						85.4
Contract termination and other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges					0	2.3	$ 14.6
Restructuring charges					(3.5)
Restructuring reserve	$ 0.2				$ 0	0.2
Contract termination and other [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			1.5	0.8		2.3
Inventory Write-down [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			11.5			15.5
Intangible Asset Write-Down [Member] | Restructuring Plan 2014 [Member] | Cost of revenues [Member]
Restructuring Cost and Reserve [Line Items]
Impairment of intangible assets						19.3
Acceleration of Certain End of Life Products [Member] | Restructuring Plan 2014 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 2.3	$ 8.4		$ 6.7

Restructuring and Other Charg70

Restructuring and Other Charges - Restructuring Reserve (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Restructuring Reserve [Roll Forward]
December 31, 2014	$ 17
Restructuring charges	(4.1)
Cash Payments	(10.5)
Non-cash Settlements and Other	0.4
December 31, 2015	2.8
Employee Severance [Member]
Restructuring Reserve [Roll Forward]
December 31, 2014	9.4
Restructuring charges	0.4
Cash Payments	(8.2)
Non-cash Settlements and Other	(1.6)
December 31, 2015	0
Facility Closing [Member]
Restructuring Reserve [Roll Forward]
December 31, 2014	7.4
Restructuring charges	(1)
Cash Payments	(2.3)
Non-cash Settlements and Other	(1.3)
December 31, 2015	2.8
Contract Termination [Member]
Restructuring Reserve [Roll Forward]
December 31, 2014	0.2
Restructuring charges	(3.5)
Cash Payments	0
Non-cash Settlements and Other	3.3
December 31, 2015	$ 0

Debt and Financing - Short and

Debt and Financing - Short and Long Term Debt (Details) - USD ($)	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Mar. 31, 2011
Debt Instrument [Line Items]
Debt, gross	$ 1,950,000,000
Unaccreted Discount	(1,300,000)
Total debt	1,948,700,000
Short-term debt	299,900,000		$ 0
Long-term debt	1,648,800,000		$ 1,349,000,000
Fixed Rate Note Due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300,000,000				$ 300,000,000
Stated interest rate	3.10%				3.10%
Effective interest rate	3.25%
Fixed rate note due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300,000,000	$ 300,000,000
Stated interest rate	3.30%	3.30%
Effective interest rate	3.47%
Fixed Rate Note Due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300,000,000				$ 300,000,000
Stated interest rate	4.60%				4.60%
Effective interest rate	4.69%
Fixed Rate Note Due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350,000,000			$ 350,000,000
Stated interest rate	4.50%			4.50%
Effective interest rate	4.63%
Fixed Rate Note Due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300,000,000	$ 300,000,000
Stated interest rate	4.35%	4.35%
Effective interest rate	4.47%
Fixed Rate Note Due 2041 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 400,000,000				$ 400,000,000
Stated interest rate	5.95%				5.95%
Effective interest rate	6.03%

Debt and Financing (Details)

Debt and Financing (Details) - USD ($)	Jun. 27, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2011
Debt Instrument [Line Items]
Repurchase price percentage related to change in control		101.00%
Financing Arrangements [Abstract]
Sale of receivables		$ 72,500,000	$ 440,300,000	$ 898,400,000
Proceeds from sale and collection of receivables		99,300,000	602,100,000	$ 843,900,000
Receivables from sale of receivables		$ 1,200,000	28,000,000
Maximum term for guarantees relating to third-party financing arrangements		3 years
Cash received from financing provider that has not been recognized as revenue		$ 1,400,000	$ 45,300,000
Financing guarantee with recourse [Member]
Financing Arrangements [Abstract]
Guarantor obligations, current carrying value		$ 9,900,000
Minimum [Member]
Financing Arrangements [Abstract]
Number of days due from receivable		30 days
Maximum [Member]
Financing Arrangements [Abstract]
Number of days due from receivable		90 days
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 500,000,000
Additional borrowing capacity	$ 200,000,000
Revolving Credit Facility [Member] | Federal Funds Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Revolving Credit Facility [Member] | ICE Benchmark Administration Settlement Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.00%
Revolving Credit Facility [Member] | Minimum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.00%
Revolving Credit Facility [Member] | Minimum [Member] | Eurodollar [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.90%
Revolving Credit Facility [Member] | Maximum [Member] | Base Rate [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	0.50%
Revolving Credit Facility [Member] | Maximum [Member] | Eurodollar [Member]
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
Fixed rate note due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Redemption Period		1 month
Long-term debt		$ 300,000,000			$ 300,000,000
Stated interest rate		3.30%			3.30%
Fixed Rate Note Due 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption, Redemption Period		3 months
Long-term debt		$ 300,000,000			$ 300,000,000
Stated interest rate		4.35%			4.35%
Fixed Rate Note Due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt		$ 350,000,000				$ 350,000,000
Stated interest rate		4.50%				4.50%
Fixed Rate Note Due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt		$ 300,000,000					$ 300,000,000
Stated interest rate		3.10%					3.10%
Fixed Rate Note Due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt		$ 300,000,000					$ 300,000,000
Stated interest rate		4.60%					4.60%
Fixed Rate Note Due 2041 [Member]
Debt Instrument [Line Items]
Long-term debt		$ 400,000,000					$ 400,000,000
Stated interest rate		5.95%					5.95%
Other Fixed Rate Notes [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption Price, Percentage		100.00%
One Month Prior to Maturity [Member] | Fixed rate note due 2020 [Member] | Treasury Rate [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption, Discount Rate, Basis Spread on Variable Rate		0.30%
One Month Prior to Maturity [Member] | Fixed Rate Note Due 2025 [Member] | Treasury Rate [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption, Discount Rate, Basis Spread on Variable Rate		0.375%
One Month Prior to Maturity [Member] | Fixed Rate Notes Due 2020 And 2025 [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption Price, Percentage		100.00%
Any Time on or After May 15, 2020 [Member] | Fixed rate note due 2020 [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption Price, Percentage		100.00%
Any Time on or After March 15, 2025 [Member] | Fixed rate note due 2020 [Member]
Financing Arrangements [Abstract]
Debt Instrument, Redemption Price, Percentage		100.00%

Equity, Stock Repurchase Activi

Equity, Stock Repurchase Activities (Details) $ / shares in Units, shares in Millions	Oct. 22, 2015$ / shares	Jul. 23, 2015$ / shares	Apr. 23, 2015$ / shares	Jan. 27, 2015$ / shares	Oct. 23, 2014$ / shares	Jul. 22, 2014$ / shares	Dec. 31, 2015USD ($)$ / shares	Sep. 30, 2015$ / shares	Jun. 30, 2015$ / shares	Mar. 31, 2015$ / shares	Dec. 31, 2014USD ($)$ / shares	Sep. 30, 2014$ / shares	Jun. 30, 2014$ / shares	Mar. 31, 2014$ / shares	Dec. 31, 2015USD ($)institutionDividend$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	Jul. 31, 2015USD ($)	Oct. 31, 2014USD ($)	Feb. 28, 2014USD ($)
Number of quarterly cash dividends declared | Dividend															4
Cash dividends declared per share of common stock (in dollars per share) | $ / shares	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0	$ 0	$ 0.40	$ 0.20	$ 0
Dividends paid															$ 156,300,000	$ 86,000,000	$ 0
Stock repurchase program, authorized amount																				$ 2,100,000,000
Repurchases under stock repurchase programs, shares repurchased | shares															45.4	46.8	28.9
Repurchases under stock repurchase programs, average price (in dollar per share) | $ / shares															$ 25.16	$ 22.42	$ 19.76
Repurchases under stock repurchase programs, amount repurchased															$ 1,142,500,000	$ 1,050,000,000	$ 570,600,000
Repurchases under accelerated share repurchase programs, shares repurchased | shares																49.3
Repurchases under accelerated share repurchase programs, average price per share (in dollar per share) | $ / shares																$ 24.35
Repurchases under stock repurchase programs, amount repurchased											$ 1,200,000,000					$ 1,200,000,000
Repurchases for tax withholding, shares repurchased | shares															0.4	0.6	0.4
Repurchases for tax withholding, average price per share (in dollar per share) | $ / shares															$ 26.70	$ 19.69	$ 20.23
Repurchases for tax withholding, amount repurchased															$ 11,100,000	$ 12,500,000	$ 7,200,000
Number of accelerated share repurchase programs | institution															2
Number of participating financial institutions in accelerated share repurchase programs | institution															2
Stock Repurchase Program 2014 [Member]
Stock repurchase program, authorized amount							$ 3,900,000,000								$ 3,900,000,000					$ 1,200,000,000
Additional amount authorized under Stock Repurchase Plan																		$ 500,000,000	$ 1,300,000,000
Stock repurchase program, remaining authorized repurchase amount							$ 532,500,000								$ 532,500,000

Equity, Accumulated Other Compr

Equity, Accumulated Other Comprehensive Income, Net of Tax (Details) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)Dividend	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Number of quarterly cash dividends declared | Dividend									4
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Beginning Balance				$ (13.8)				$ 64.6	$ (13.8)	$ 64.6
Other comprehensive gain (loss) before reclassifications									(14.5)	30.4
Amount reclassified from accumulated other comprehensive income									9.1	(108.8)
Other comprehensive gain (loss), net									(5.4)	(78.4)	$ 59.9
Ending Balance	$ (19.2)				$ (13.8)				(19.2)	(13.8)	64.6
Other expense	(18.5)	$ (8.4)	$ (17.1)	(15.8)	7.4	$ (6.8)	$ 178.6	154.2	(59.8)	333.4	(40.4)
Research and development expense	247.2	247	251.6	248.7	233.5	253.2	255.5	264	994.5	1,006.2	1,043.2
Selling and marketing expense	255.9	235.3	232.4	220.2	243	249.2	258	273.4	943.8	1,023.6	1,075.9
General and administrative expense	60.3	57.1	56.3	55.2	40.6	55	60.6	74.9	228.9	231.1	217.3
Cost of revenues	477.2	$ 451.2	$ 440.7	410.1	426.5	$ 411.1	$ 481.3	450	1,779.2	1,768.9	1,727.7
Unrealized Gains (Losses) on Available-for- Sale Securities [Member]
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Beginning Balance				8.4				66.2	8.4	66.2
Other comprehensive gain (loss) before reclassifications									9.1	48.7
Amount reclassified from accumulated other comprehensive income									0.5	(106.5)
Other comprehensive gain (loss), net									8.6	(57.8)
Ending Balance	17				8.4				17	8.4	66.2
Other expense									0.5	104.3
Research and development expense										1.4
Selling and marketing expense										0.3
General and administrative expense										0.7
Cost of revenues										0.1
Unrealized Gains (Losses) on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Beginning Balance				(4.2)				2.2	(4.2)	2.2
Other comprehensive gain (loss) before reclassifications									(6.7)	(4.1)
Amount reclassified from accumulated other comprehensive income									(9.6)	(2.3)
Other comprehensive gain (loss), net									2.9	(6.4)
Ending Balance	(1.3)				(4.2)				(1.3)	(4.2)	2.2
Research and development expense									0.2
Selling and marketing expense									6
General and administrative expense									0.5
Cost of revenues									2.9
Foreign Currency Translation Adjustments [Member]
Accumulated Other Comprehensive Income, Net of Tax [Roll Forward]
Beginning Balance				$ (18)				$ (3.8)	(18)	(3.8)
Other comprehensive gain (loss) before reclassifications									(16.9)	(14.2)
Amount reclassified from accumulated other comprehensive income									0	0
Other comprehensive gain (loss), net									(16.9)	(14.2)
Ending Balance	$ (34.9)				$ (18)				$ (34.9)	$ (18)	$ (3.8)

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	May. 19, 2015
Share-Based Compensation Plans
Common shares outstanding from equtiy awards through acquisition	1,700,000
Common stock - shares issued	384,000,000	416,200,000
Stock Option Activities
Beginning Balance, Number of Shares	9,900,000	23,100,000	34,100,000
Options Canceled, Number of Shares	(100,000)	(600,000)	(1,300,000)
Options Exercised, Number of Shares	(3,500,000)	(5,400,000)	(5,600,000)
Options Expired, Number of Shares	(2,700,000)	(7,200,000)	(4,100,000)
Ending Balance, Number of Shares	3,600,000	9,900,000	23,100,000	34,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning Balance, Weighted Average Exercise Price (in USD per share)	$ 24.87	$ 25.15	$ 24.13
Options Canceled, Weighted Average Exercise Price (in USD per share)	23.65	30.15	29.56
Options Exercised, Weighted Average Exercise Price (in USD per share)	19.78	19.76	15.58
Options Expired, Weighted Average Exercise Price (in USD per share)	27.99	29.11	28.35
Ending Balance, Weighted Average Exercise Price (in USD per share)	$ 27.52	$ 24.87	$ 25.15	$ 24.13
Weighted Average Remaining Contractual Term at Period End	2 years 1 month 6 days	2 years	2 years 4 months 24 days	3 years 1 month 6 days
Aggregate Intrinsic Value at Period End	$ 16,600,000	$ 24,700,000	$ 44,600,000	$ 52,500,000
Vested or Expected-to-Vest Options, Number of Shares at Period End	3,600,000
Vested or Expected-to-Vest Options, Weighted Average Exercise Price at Period End (in USD per share)	$ 27.58
Vested and Expected-to-Vest Options, Weighted Average Remaining Contractual Term at Period End	2 years 1 month 6 days
Vested or Expected-to-Vest Options, Aggregate Intrinsic Value at Period End	$ 16,300,000
Exercisable Options, Number of Shares at Period End	3,400,000
Exercisable Options, Weighted Average Exercise Price at Period End (in USD per share)	$ 28.82
Exercisable Options, Weighted Average Remaining Contractual Term at Period End	1 year 9 months 18 days
Exercisable Options, Aggregate Intrinsic Value at Period End	$ 12,100,000
Share Price (in USD per share)	$ 27.60
Intrinsic value of options exercised in period	$ 27,500,000	33,400,000	29,400,000
Total Fair Value of Options Vested	$ 7,000,000	$ 20,800,000	$ 45,200,000
Mykonos, Contrail and WANDL [Member]
Share-Based Compensation Plans
Options Assumed, Number of Shares		1,500,000
Stock Compensation Plan [Member]
Share-Based Compensation Plans
Number of shares of common stock reserved for future issuance for equity incentive plans	66,500,000
Stock Options [Member] | Prior to 2006 [Member] | Prior to 2006 [Member]
Share-Based Compensation Plans
Maximum Term for Options	10 years
Equity Incentive Plan 2015 [Member]
Share-Based Compensation Plans
Number of shares in authorized	38,000,000				38,000,000
Number of Shares Available for Future Issuance	36,700,000
Equity Incentive Plan 2015, 2006, and 1996 [Member]
Share-Based Compensation Plans
Shares outstanding under 2006 plan	20,500,000
Equity Incentive Plan 1996 and 2006 [Member]
Share-Based Compensation Plans
Maximum Additional Shares Expire Unexercised, Under 1996 and 2000 Plan	29,000,000				29,000,000
Number of Shares Available for Future Issuance	0
Equity Incentive Plan 2006 [Member]
Share-Based Compensation Plans
Number of Shares Available for Future Issuance		47,800,000
Stock Option Activities
Options Canceled, Number of Shares	(100,000)
Options Expired, Number of Shares	(2,700,000)
Equity Incentive Plan 2006 [Member] | Stock Options [Member] | From 2006 [Member]
Share-Based Compensation Plans
Maximum Term for Options	7 years
Employee Stock Purchase Plan 2008 [Member]
Share-Based Compensation Plans
Number of Shares Available for Future Issuance	7,600,000
Maximum Term for Options	1 year
Discount on share purchase price for purchases made under ESPP	15.00%
Periodic Payroll Deduction - Percentage of Base Salary	10.00%
Maximum Purchase of Common Stock, Shares	6,000
Number of shares of common stock reserved for future issuance for equity incentive plans	26,000,000
Period for share purchases under ESPP	12 months
Maximum Purchase of Common Stock, Value	$ 25,000
Common stock - shares issued	18,400,000
Employee Stock Purchase Plan 2008 Additional Authorization [Member]
Share-Based Compensation Plans
Number of shares of common stock reserved for future issuance for equity incentive plans	7,000,000

Employee Benefit Plans, Options

Employee Benefit Plans, Options Outstanding Exercise Price Range (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding (in number of shares)	3.6
Weighted Average Remaining Contractual Life (in years)	2 years 1 month 6 days
Weighted Average Exercise (in USD per share)	$ 27.52	$ 24.87	$ 25.15	$ 24.13
Number Exercisable (in number of shares)	3.4
Weighted Average Exercise Price (in USD per share)	$ 28.82
$0.03 - $14.68
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	0.03
Exercise Price Range, Upper Range Limit	$ 14.68
Number Outstanding (in number of shares)	0.4
Weighted Average Remaining Contractual Life (in years)	5 years 3 months 18 days
Weighted Average Exercise (in USD per share)	$ 3.38
Number Exercisable (in number of shares)	0.3
Weighted Average Exercise Price (in USD per share)	$ 4.94
$15.09 - $18.45
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	15.09
Exercise Price Range, Upper Range Limit	$ 18.45
Number Outstanding (in number of shares)	0.4
Weighted Average Remaining Contractual Life (in years)	8 months 12 days
Weighted Average Exercise (in USD per share)	$ 15.58
Number Exercisable (in number of shares)	0.3
Weighted Average Exercise Price (in USD per share)	$ 15.47
$18.49 - $26.10
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	18.49
Exercise Price Range, Upper Range Limit	$ 26.10
Number Outstanding (in number of shares)	0.4
Weighted Average Remaining Contractual Life (in years)	2 years 3 months 18 days
Weighted Average Exercise (in USD per share)	$ 24.11
Number Exercisable (in number of shares)	0.3
Weighted Average Exercise Price (in USD per share)	$ 24.19
$26.39 - $27.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	26.39
Exercise Price Range, Upper Range Limit	$ 27.44
Number Outstanding (in number of shares)	0.5
Weighted Average Remaining Contractual Life (in years)	1 year
Weighted Average Exercise (in USD per share)	$ 26.97
Number Exercisable (in number of shares)	0.5
Weighted Average Exercise Price (in USD per share)	$ 26.97
$27.62 - $29.33
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	27.62
Exercise Price Range, Upper Range Limit	$ 29.33
Number Outstanding (in number of shares)	0.1
Weighted Average Remaining Contractual Life (in years)	2 years
Weighted Average Exercise (in USD per share)	$ 28.88
Number Exercisable (in number of shares)	0.1
Weighted Average Exercise Price (in USD per share)	$ 28.88
$29.89 - $29.89
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	29.89
Exercise Price Range, Upper Range Limit	$ 29.89
Number Outstanding (in number of shares)	0.5
Weighted Average Remaining Contractual Life (in years)	1 year 2 months 12 days
Weighted Average Exercise (in USD per share)	$ 29.89
Number Exercisable (in number of shares)	0.5
Weighted Average Exercise Price (in USD per share)	$ 29.89
$30.01 - $36.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	30.01
Exercise Price Range, Upper Range Limit	$ 36.49
Number Outstanding (in number of shares)	0.4
Weighted Average Remaining Contractual Life (in years)	1 year 10 months 24 days
Weighted Average Exercise (in USD per share)	$ 32.76
Number Exercisable (in number of shares)	0.4
Weighted Average Exercise Price (in USD per share)	$ 32.76
$38.93 - $38.93
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	38.93
Exercise Price Range, Upper Range Limit	$ 38.93
Number Outstanding (in number of shares)	0.1
Weighted Average Remaining Contractual Life (in years)	2 years 4 months 24 days
Weighted Average Exercise (in USD per share)	$ 38.93
Number Exercisable (in number of shares)	0.1
Weighted Average Exercise Price (in USD per share)	$ 38.93
$40.26 - $40.26
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	40.26
Exercise Price Range, Upper Range Limit	$ 40.26
Number Outstanding (in number of shares)	0.5
Weighted Average Remaining Contractual Life (in years)	2 years 2 months 12 days
Weighted Average Exercise (in USD per share)	$ 40.26
Number Exercisable (in number of shares)	0.6
Weighted Average Exercise Price (in USD per share)	$ 40.26
$44.00 - $44.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range, Lower Range Limit	44
Exercise Price Range, Upper Range Limit	$ 44
Number Outstanding (in number of shares)	0.3
Weighted Average Remaining Contractual Life (in years)	2 years 1 month 6 days
Weighted Average Exercise (in USD per share)	$ 44
Number Exercisable (in number of shares)	0.3
Weighted Average Exercise Price (in USD per share)	$ 44

Employee Benefit Plans, Share B

Employee Benefit Plans, Share Based Compensation, Equity Instruments Other Than Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Feb. 20, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Vested and Expected-to-Vest Options, Weighted Average Remaining Contractual Term at Period End	2 years 1 month 6 days
Fair value of RSUs, RSAs and PSAs	$ 202.7	$ 238.5	$ 221.5
Intended quarterly dividend (in USD per share)					$ 0.1
Dividends paid	$ 156.3	$ 86	$ 0
Restricted Stock Units (RSUs) [Member]
Restricted Stock Units And Performance Share Awards Activities
Awards Granted, Number of Shares	8,900,000	10,000,000	10,300,000
Awards Assumed, Number of Shares		400,000
Awards Vested, Number of Shares	(7,200,000)	(7,300,000)	(6,100,000)
Awards Canceled, Number of Shares	(2,300,000)	(4,000,000)	(3,400,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Awards Granted, Weighted Average Grant-Date Fair Value (in USD per share)	$ 23.41	$ 22.52	$ 20.32
Awards Assumed, Weighted Average Grant-Date Fair Value (in USD per share)		22.66
Awards Vested, Weighted Average Grant-Date Fair Value (in USD per share)	22.58	22.98	26.15
Awards Canceled, Weighted Average Grant-Date Fair Value (in USD per share)	$ 22.18	$ 21.63	$ 22.99
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	4 years
Performance Shares (PSAs) [Member]
Restricted Stock Units And Performance Share Awards Activities
Awards Granted, Number of Shares	1,000,000	1,400,000	2,200,000
Awards Assumed, Number of Shares		200,000
Awards Vested, Number of Shares	(300,000)	(1,100,000)	(1,100,000)
Awards Canceled, Number of Shares	(1,000,000)	(3,200,000)	(1,700,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Awards Granted, Weighted Average Grant-Date Fair Value (in USD per share)	$ 23.76	$ 24.25	$ 21.27
Awards Assumed, Weighted Average Grant-Date Fair Value (in USD per share)		22.66
Awards Vested, Weighted Average Grant-Date Fair Value (in USD per share)	22.52	36.19	28.52
Awards Canceled, Weighted Average Grant-Date Fair Value (in USD per share)	$ 22.27	$ 30.43	$ 29.10
Aggregate Number Of Shares Subject to PSAs Granted	700,000	700,000	1,100,000
Minimum shares to be Issued on achievement of performance goals in respect of PSAs	0	0	0
Maximum shares to be issued on achievement of performance goals in respect of PSAs	1,000,000	1,400,000	2,200,000
Performance Shares (PSAs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	2 years
Performance Shares (PSAs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
RSUs, RSAs, and PSAs [Member]
Restricted Stock Units And Performance Share Awards Activities
Beginning Balance, Number of Shares	21,300,000	25,400,000	26,800,000
Ending Balance, Number of Shares	18,600,000	21,300,000	25,400,000	26,800,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Beginning Balance, Weighted Average Grant-Date Fair Value (in USD per share)	$ 22.05	$ 23.44	$ 27.76
Ending Balance, Weighted Average Grant-Date Fair Value (in USD per share)	$ 22.71	$ 22.05	$ 23.44	$ 27.76
Weighted Average Remaining Contractual Term (In Years)	1 year 1 month 6 days	1 year 1 month 6 days	1 year 1 month 6 days	1 year 8 months 12 days
RSUs and PSAs, Aggregate Intrinsic Value at Period End	$ 514.1	$ 475	$ 573.5	$ 565
Vested and Expected-to-Vest RSUs and PSAs, Number of Shares at Period End	15,300,000
Vested and Expected-to-Vest RSUs and PSAs, Grant Date Fair Value (in USD per share)	$ 22.59
Vested and Expected-to-Vest Options, Weighted Average Remaining Contractual Term at Period End	1 year
Vested and Expected-to-Vest RSUs and PSAs, Aggregate Intrinsic Value	$ 421.3
RSA [Member]
Restricted Stock Units And Performance Share Awards Activities
Awards Assumed, Number of Shares		900,000
Awards Vested, Number of Shares	(1,800,000)	(1,400,000)	(1,600,000)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Awards Assumed, Weighted Average Grant-Date Fair Value (in USD per share)		$ 22.66
Awards Vested, Weighted Average Grant-Date Fair Value (in USD per share)	$ 20.13	$ 19.59	$ 19.59

Employee Benefit Plans, Shares

Employee Benefit Plans, Shares Available For Grant (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 19, 2015
Shares Available For Grant
Options Canceled, Number of Shares	100,000	600,000	1,300,000
Options Expired, Number of Shares	2,700,000	7,200,000	4,100,000
Common Stock for Each Share Subject to RSUs and PSAs	2.1
Restricted Stock Units and Performance Share Awards [Member]
Shares Available For Grant
Fair Market Value on Date of Grant For RSUS And PSAS Issued at Discount, Maximum Percentage	100.00%
Equity Incentive Plan 2006 [Member]
Shares Available For Grant
Beginning Balance, Number of Shares	47,800,000
Awards Granted, Number of Shares	(20,700,000)
Awards Canceled, Number of Shares	7,000,000
Options Canceled, Number of Shares	100,000
Options Expired, Number of Shares	2,700,000
Shares discontinued, Number of Shares	(38,200,000)
Ending Balance, Number of Shares		47,800,000
Equity Incentive Plan 2015 [Member]
Shares Available For Grant
Shares Authorized Under the 2015 Plan, Number of Shares	38,000,000			38,000,000
Ending Balance, Number of Shares	36,700,000
Equity Incentive Plan 1996 and 2006 [Member]
Shares Available For Grant
Ending Balance, Number of Shares	0
Maximum Additional Shares Expire Unexercised, Under 1996 and 2000 Plan	29,000,000			29,000,000

Employee Benefit Plans, Assumpt

Employee Benefit Plans, Assumptions and Resulting Estimates of Fair Value (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Purchase Plan [Member]
Estimates of Fair Value
Volatility	29.00%	30.00%	36.00%
Risk-free interest rate	0.10%	0.10%	0.10%
Expected life (years)	6 months	6 months	6 months
Dividend yield	1.70%		0.00%
Weighted-average fair value per share	$ 5.63	$ 5.72	$ 5.54
Market-based RSUs [Member]
Estimates of Fair Value
Volatility	34.00%	36.00%
Risk-free interest rate	1.40%	1.60%
Dividend yield	1.80%
Weighted-average fair value per share	$ 14.97	$ 16.89
Minimum [Member] | Stock Options [Member]
Estimates of Fair Value
Dividend yield		0.00%
Minimum [Member] | Market-based RSUs [Member]
Estimates of Fair Value
Dividend yield		0.00%
Maximum [Member] | Stock Options [Member]
Estimates of Fair Value
Dividend yield		1.80%
Maximum [Member] | Market-based RSUs [Member]
Estimates of Fair Value
Dividend yield		2.00%
Employee Stock Purchase Plan 2008 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period (in months)	6 months
Common shares purchased through ESPP	2.7	2.9	3.3
Average exercise price of shares purchased through ESPP (in dollar per share)	$ 19.25	$ 19.30	$ 16.53

Employee Benefit Plans, Share80

Employee Benefit Plans, Share Based Compensation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 217.3	$ 240	$ 244.6
Stock Options [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	6.6	14.9	31.5
Unrecognized Compensation Cost	$ 2.1
Weighted Average Period that Unrecognized Compensation Cost Will be Recognized (in years)	7 months 6 days
RSUs, RSAs, and PSAs [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 197.3	209.7	196.8
Employee Stock Purchase Plan [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	13.4	15.4	16.3
Restricted Stock Units and Performance Share Awards [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Unrecognized Compensation Cost	$ 211.2
Weighted Average Period that Unrecognized Compensation Cost Will be Recognized (in years)	1 year 8 months 12 days
Cost of Revenues, Product [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 5.6	5	4.7
Cost of Revenues, Service [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	13.8	14.2	15.4
Research and Development Expense [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	125.4	134.5	127.6
Selling and Marketing Expense [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	45.6	60.2	70.9
General and Administrative Expense [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-Based Compensation Expense	$ 26.9	$ 26.1	$ 26

Employee Benefit Plans, 401(k)

Employee Benefit Plans, 401(k) plan and Deferred Compensation Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Benefit Textuals [Abstract]
Employee Contribution Matched in Percent	30.00%
Matching Contributions to Plan	$ 19.6	$ 20.2	$ 20.7
NQDC [Member]
Employee Benefit Textuals [Abstract]
Deferred Compensation Liability	$ 17.7	$ 16.3

Segments (Details)

Segments (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Revenues [Abstract]
Total net revenues	$ 1,319.6	$ 1,248.6	$ 1,222.2	$ 1,067.4	$ 1,101.6	$ 1,125.9	$ 1,229.5	$ 1,170.1	$ 4,857.8	$ 4,627.1	$ 4,669.1
Routing [Member]
Net Revenues [Abstract]
Total net revenues									2,359.2	2,223.9	2,318
Switching [Member]
Net Revenues [Abstract]
Total net revenues									768.3	721.2	638
Security [Member]
Net Revenues [Abstract]
Total net revenues									435.6	463.6	563.9
Total product [Member]
Net Revenues [Abstract]
Total net revenues									3,563.1	3,408.7	3,519.9
Total service [Member]
Net Revenues [Abstract]
Total net revenues									$ 1,294.7	$ 1,218.4	$ 1,149.2

Segments, Geographical (Details

Segments, Geographical (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Revenues by Geographic Region [Line Items]
Total net revenues	$ 1,319.6	$ 1,248.6	$ 1,222.2	$ 1,067.4	$ 1,101.6	$ 1,125.9	$ 1,229.5	$ 1,170.1	$ 4,857.8	$ 4,627.1	$ 4,669.1
Property and equipment, net and purchased intangible assets, net	1,054.9				966.7				1,054.9	966.7
United States [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									2,568.6	2,410.6	2,381.5
Property and equipment, net and purchased intangible assets, net	925.5				871.7				925.5	871.7
Other Americas [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									223.6	219.7	232
Americas [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									2,792.2	2,630.3	2,613.5
EMEA [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									1,320.3	1,263.3	1,256.9
Asia Pacific [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues									745.3	733.5	$ 798.7
International [Member]
Net Revenues by Geographic Region [Line Items]
Property and equipment, net and purchased intangible assets, net	$ 129.4				$ 95				$ 129.4	$ 95

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Components of income before provision for income taxes and noncontrolling interest
Domestic									$ 456.3	$ (509.7)	$ 248.7
Foreign									395.9	423.4	276.8
Income (loss) before income taxes	$ 260.6	$ 249.6	$ 226	$ 116	$ (694.4)	$ 165.6	$ 294.5	$ 148	852.2	(86.3)	525.5
Current provision (benefit):
Federal									181.4	180.1	(12.9)
States									15.9	15.2	(5)
Foreign									43.3	33.7	32.5
Total current provision (benefit)									240.6	229	14.6
Deferred provision (benefit):
Federal									(16.7)	17.3	51.2
States									(0.4)	1.2	(2.7)
Foreign									(5)	0.5	22.6
Total deferred provision (benefit)									(22.1)	19	71.1
Income tax benefits attributable to employee stock plan activity									0	0	0
Total provision for income taxes	62.8	51.9	68	35.8	75.2	62	73.4	37.4	218.5	248	85.7
Income tax reconciliation
Expected provision at 35% rate									298.3	(30.2)	184
State taxes (benefit), net of federal benefit									8.9	9.5	(3.6)
Foreign income at different tax rates									(68.9)	(90.2)	(37.7)
R&D tax credits									(12.7)	(17.1)	(32.5)
Share-based compensation									13.2	25.3	25.6
Non-deductible goodwill impairment									0	297.5	0
Gain on sale of Junos Pulse									0	75.6	0
Release of valuation allowance									0	(22.8)	0
Settlement with tax authorities									0	0	(28.3)
Domestic production activities									(15.1)	(6.8)	(26.3)
Non-deductible compensation									3.7	3.2	1.5
Cost sharing adjustment									(13.2)	0	0
Other									4.3	4	3
Total provision for income taxes	$ 62.8	51.9	$ 68	$ 35.8	$ 75.2	$ 62	$ 73.4	$ 37.4	$ 218.5	$ 248	85.7
Tax benefit related to cost sharing agreement		$ 70.3
Net income tax benefit related to items unique during current year											64.2
Income tax benefit for a multi-year claim related to the U.S. production activities deduction											19.7
U.S. federal R&D tax credit resulting from the American Taxpayer Relief Act of 2012											$ 16.2

Income Taxes, Deferred Taxes (D

Income Taxes, Deferred Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carry-forwards	$ 1	$ 1.3
Foreign tax credit carry-forwards	75.4	69.7
Research and other credit carry-forwards	128.7	122.5
Deferred revenue	109.3	104.9
Stock-based compensation	49.1	55.8
Cost sharing adjustment	70.1	0
Reserves and accruals not currently deductible	173.9	129.8
Other	19.2	19.8
Total deferred tax assets	626.7	503.8
Valuation allowance	(146.2)	(144.5)
Deferred tax assets, net of valuation allowance	480.5	359.3
Deferred tax liabilities:
Property and equipment basis differences	(44.1)	(35.6)
Purchased intangibles	(3.1)	(16.7)
Unremitted foreign earnings	(365.4)	(260.6)
Deferred compensation and other	(12)	(5.1)
Other	0	0
Total deferred tax liabilities	(424.6)	(318)
Net deferred tax assets	55.9	41.3
Valuation allowance	146.2	144.5
Increase (decrease) in DTA valuation allowance	1.7	$ (11.2)
Cumulative undistributed earnings of certain foreign subsidiaries	2,200
California [Member]
Deferred tax liabilities:
Net operating loss carry-forwards	49.5
Tax credit carry-forwards	237.1
Tax credit carry-forward to be credited to APIC when realized	19.5
California Deferred Tax Assets [Member]
Deferred tax assets:
Valuation allowance	(128.1)
Deferred tax liabilities:
Valuation allowance	128.1
Net operating loss carry-forwards	48
Massachusetts Deferred Tax Assets [Member]
Deferred tax assets:
Valuation allowance	(9.7)
Deferred tax liabilities:
Valuation allowance	9.7
Capital Loss Carryforward [Member]
Deferred tax assets:
Valuation allowance	(8.4)
Deferred tax liabilities:
Valuation allowance	$ 8.4

Income Taxes, Income Tax Contin

Income Taxes, Income Tax Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2009
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 199.2	$ 137.6	$ 136.1
Current Year [Abstract]
Additions	18.1	62.5	15.8
Prior Years [Abstract]
Additions	5.3	0.6	22.6
Reductions	(2.9)	0	(2.2)
Settlements	0	0	(31.1)
Lapses in statutes of limitations	(3.6)	(1.5)	(3.6)
Balance at end of year	216.1	199.2	137.6
Unrecognized tax benefits that would impact effective tax rate	181.8
Tax expense recognized for net interest and penalties in the Consolidated Statements of Operations	2.5	2.8	0.6
Settlement including interest with the IRS related to intercompany R&D cost sharing arrangement			19.6
Maximum [Member]
Prior Years [Abstract]
Decrease in unrecognized tax benefits is reasonably possible	18.6
India Tax Authority [Member]
Prior Years [Abstract]
Penalties and interest accrued related to investigation of 2004 to 2008 tax return by India tax authorities				$ 4.6
Other Long Term Liabilities [Member]
Prior Years [Abstract]
Interest and penalties accrued related to unrecognized tax benefits	$ 24.1	$ 22.3	$ 18.4

Net Income per Share (Details)

Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income (loss)	$ 197.8	$ 197.7	$ 158	$ 80.2	$ (769.6)	$ 103.6	$ 221.1	$ 110.6	$ 633.7	$ (334.3)	$ 439.8
Denominator:
Weighted-average shares used to compute basic net income (loss) per share									390.6	457.4	501.8
Dilutive effect of employee stock awards									8.8	0	8.5
Weighted-average shares used to compute diluted net income (loss) per share									399.4	457.4	510.3
Net income (loss) per share attributable to Juniper Networks common stockholders:
Basic (in dollars per share)	$ 0.52	$ 0.52	$ 0.41	$ 0.20	$ (1.81)	$ 0.23	$ 0.47	$ 0.23	$ 1.62	$ (0.73)	$ 0.88
Diluted (in dollars per share)	$ 0.51	$ 0.51	$ 0.40	$ 0.19	$ (1.81)	$ 0.23	$ 0.46	$ 0.22	$ 1.59	$ (0.73)	$ 0.86
Net Income (Loss) per Share Textuals
Anti-dilutive shares excluded from computation of diluted earnings per share									3.4	20.8	13.2

Commitments and Contingencies88

Commitments and Contingencies (Details) ft² in Thousands	Jul. 10, 2015USD ($)ft²	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Mar. 31, 2015USD ($)	Mar. 31, 2014USD ($)	Mar. 31, 2011USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016		$ 35,700,000
2,017		25,600,000
2,018		18,600,000
2,019		10,300,000
2,020		7,800,000
Thereafter		15,700,000
Total	$ 118,100,000	113,700,000
Rent expense		43,200,000	$ 46,000,000	$ 52,800,000
Lease extension term, total	20 years
Lease extension term increments	10 years
Square Feet of Leased Unit | ft²	63
Tenant Allowance	$ 6,000,000
Property and equipment, net		1,021,000,000	904,300,000
Purchase commitments		591,200,000
Accrual for estimated carrying charges or obsolete materials charges		18,000,000
Short-term debt		299,900,000	0
Senior notes		1,648,800,000	1,349,000,000
Indemnity-related and service-related escrows		36,200,000
Campus build-out commitments		3,500,000
Non-cancelable agreements		33,400,000
Long-term income tax payable		187,300,000	$ 177,500,000
Minimum [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Lease extension term increments	5 years
Maximum [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Lease extension term increments	10 years
Fixed Rate Note Due 2016 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 300,000,000					$ 300,000,000
Stated interest rate		3.10%					3.10%
Fixed Rate Note Due 2021 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 300,000,000					$ 300,000,000
Stated interest rate		4.60%					4.60%
Fixed Rate Notes Due 2021 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 300,000,000
Fixed rate note due 2020 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 300,000,000			$ 300,000,000
Stated interest rate		3.30%			3.30%
Fixed Rate Note Due 2024 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 350,000,000				$ 350,000,000
Stated interest rate		4.50%				4.50%
Fixed Rate Note Due 2025 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 300,000,000			$ 300,000,000
Stated interest rate		4.35%			4.35%
Fixed Rate Note Due 2041 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 400,000,000					$ 400,000,000
Stated interest rate		5.95%					5.95%
Fixed Rate Notes Due 2041 [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Long-term debt		$ 400,000,000
Construction in Progress [Member]
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Property and equipment, net		$ 45,600,000

Commitments and Contingencies,

Commitments and Contingencies, Guarantees (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Financing guarantees, bank guarantees, and standby letters of credit [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$ 15.8	$ 26.2
Financing guarantee with recourse [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	9.9
Other Current Liabilities [Member] | Indemnification Agreement [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$ 15

Selected Quarterly Financial 90

Selected Quarterly Financial Data (Unaudited) (Details) - USD ($)	Oct. 22, 2015	Jul. 23, 2015	Apr. 23, 2015	Jan. 27, 2015	Oct. 23, 2014	Jul. 22, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net revenues:
Product							$ 973,900,000	$ 925,400,000	$ 899,700,000	$ 764,100,000	$ 794,000,000	$ 809,500,000	$ 929,200,000	$ 876,000,000	$ 3,563,100,000	$ 3,408,700,000	$ 3,519,900,000
Service							345,700,000	323,200,000	322,500,000	303,300,000	307,600,000	316,400,000	300,300,000	294,100,000	1,294,700,000	1,218,400,000	1,149,200,000
Total net revenues							1,319,600,000	1,248,600,000	1,222,200,000	1,067,400,000	1,101,600,000	1,125,900,000	1,229,500,000	1,170,100,000	4,857,800,000	4,627,100,000	4,669,100,000
Cost of revenues:
Product							346,500,000	322,600,000	311,700,000	288,800,000	310,900,000	290,000,000	359,300,000	326,600,000	1,269,600,000	1,286,800,000	1,276,600,000
Service							130,700,000	128,600,000	129,000,000	121,300,000	115,600,000	121,100,000	122,000,000	123,400,000	509,600,000	482,100,000	451,100,000
Total cost of revenues							477,200,000	451,200,000	440,700,000	410,100,000	426,500,000	411,100,000	481,300,000	450,000,000	1,779,200,000	1,768,900,000	1,727,700,000
Gross margin							842,400,000	797,400,000	781,500,000	657,300,000	675,100,000	714,800,000	748,200,000	720,100,000	3,078,600,000	2,858,200,000	2,941,400,000
Operating expenses:
Research and development							247,200,000	247,000,000	251,600,000	248,700,000	233,500,000	253,200,000	255,500,000	264,000,000	994,500,000	1,006,200,000	1,043,200,000
Sales and marketing							255,900,000	235,300,000	232,400,000	220,200,000	243,000,000	249,200,000	258,000,000	273,400,000	943,800,000	1,023,600,000	1,075,900,000
General and administrative							60,300,000	57,100,000	56,300,000	55,200,000	40,600,000	55,000,000	60,600,000	74,900,000	228,900,000	231,100,000	217,300,000
Restructuring and other (benefits) charges							(100,000)	0	(1,900,000)	1,400,000	9,800,000	(15,000,000)	58,200,000	114,000,000	(600,000)	167,000,000	39,100,000
Impairment of goodwill											850,000,000	0	0	0	0	850,000,000	0
Total operating expenses							563,300,000	539,400,000	538,400,000	525,500,000	1,376,900,000	542,400,000	632,300,000	726,300,000	2,166,600,000	3,277,900,000	2,375,500,000
Operating income (loss)							279,100,000	258,000,000	243,100,000	131,800,000	(701,800,000)	172,400,000	115,900,000	(6,200,000)	912,000,000	(419,700,000)	565,900,000
Other (expense) income, net							(18,500,000)	(8,400,000)	(17,100,000)	(15,800,000)	7,400,000	(6,800,000)	178,600,000	154,200,000	(59,800,000)	333,400,000	(40,400,000)
Income (loss) before income taxes							260,600,000	249,600,000	226,000,000	116,000,000	(694,400,000)	165,600,000	294,500,000	148,000,000	852,200,000	(86,300,000)	525,500,000
Income tax provision							62,800,000	51,900,000	68,000,000	35,800,000	75,200,000	62,000,000	73,400,000	37,400,000	218,500,000	248,000,000	85,700,000
Net income (loss)							$ 197,800,000	$ 197,700,000	$ 158,000,000	$ 80,200,000	$ (769,600,000)	$ 103,600,000	$ 221,100,000	$ 110,600,000	$ 633,700,000	$ (334,300,000)	$ 439,800,000
Net income (loss) per share:
Basic (in dollars per share)							$ 0.52	$ 0.52	$ 0.41	$ 0.20	$ (1.81)	$ 0.23	$ 0.47	$ 0.23	$ 1.62	$ (0.73)	$ 0.88
Diluted (in dollars per share)							0.51	0.51	0.40	0.19	(1.81)	0.23	0.46	0.22	1.59	(0.73)	0.86
Cash dividends declared per share of common stock (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0	$ 0	$ 0.40	$ 0.20	$ 0
Interest expense, long-term debt															$ 79,800,000	$ 57,500,000	$ 45,200,000
Cost sharing adjustment															(13,200,000)	0	0
Cost-method investments, realized gains (loss)							$ 7,300,000								6,800,000		7,100,000
Restructuring charges															(4,100,000)
Publicly-traded equity and privately-held investments, net realized gain														$ 163,000,000		163,000,000
Net gain on legal settlement												$ 800,000	$ 195,300,000		0	196,100,000	0
Gain (loss) on disposition of business											$ 19,600,000				0	19,600,000	0
Security [Member]
Net revenues:
Total net revenues															435,600,000	463,600,000	$ 563,900,000
Operating expenses:
Impairment of goodwill											850,000,000					850,000,000
Asset Write-Down [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges											20,600,000	2,900,000	8,900,000	84,700,000		12,300,000
Employee Severance [Member]
Net income (loss) per share:
Restructuring charges															400,000
Employee Severance [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges											6,900,000	7,100,000	9,900,000	28,000,000		52,000,000
Contract Termination [Member]
Net income (loss) per share:
Restructuring charges															(3,500,000)
Contract Termination [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges													1,500,000	800,000		2,300,000
Acceleration of Certain End of Life Products [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges													2,300,000	$ 8,400,000		6,700,000
Facility Closing [Member]
Net income (loss) per share:
Restructuring charges															(1,000,000)
Facility Closing [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges											$ 1,600,000	$ 25,000,000	37,600,000			14,200,000
Inventory Write-down [Member] | Restructuring Plan 2014 [Member]
Net income (loss) per share:
Restructuring charges													$ 11,500,000			$ 15,500,000
Fixed rate note due 2020 [Member]
Net income (loss) per share:
Long-term debt							$ 300,000,000			$ 300,000,000					$ 300,000,000
Stated interest rate							3.30%			3.30%					3.30%
Fixed Rate Note Due 2025 [Member]
Net income (loss) per share:
Long-term debt							$ 300,000,000			$ 300,000,000					$ 300,000,000
Stated interest rate							4.35%			4.35%					4.35%
Fixed Rate Notes Due 2020 And 2025 [Member]
Net income (loss) per share:
Interest expense, long-term debt															$ 19,100,000

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Jan. 27, 2016	Oct. 22, 2015	Jul. 23, 2015	Apr. 23, 2015	Jan. 27, 2015	Oct. 23, 2014	Jul. 22, 2014	Jan. 31, 2016	Feb. 19, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Cash dividends declared per share of common stock (in dollars per share)		$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10			$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0.10	$ 0	$ 0	$ 0.40	$ 0.20	$ 0
Repurchases under stock repurchase programs, average price (in dollar per share)																		$ 25.16	$ 22.42	$ 19.76
Stock Repurchase Program 2014 [Member]
Subsequent Event [Line Items]
Stock repurchase program, remaining authorized repurchase amount										$ 532.5								$ 532.5
Subsequent Event [Member] | Stock Repurchase Program 2014 [Member]
Subsequent Event [Line Items]
Common stock repurchased									3.1
Common stock repurchased, value									$ 75
Repurchases under stock repurchase programs, average price (in dollar per share)									$ 23.89
Stock repurchase program, remaining authorized repurchase amount									$ 457.5
Subsequent Event [Member] | First Quarter of 2015 [Member]
Subsequent Event [Line Items]
Cash dividends declared per share of common stock (in dollars per share)	$ 0.10
Subsequent Event [Member] | BTI Systems, Inc [Member]
Subsequent Event [Line Items]
Consideration transferred								$ 65

Schedule II- Valuation and Qu92

Schedule II- Valuation and Qualifying Account (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of year	$ 4.7	$ 5.4	$ 9.5
Charged to (Reversed from) Costs and Expenses	6.5	(0.7)	(3.8)
Write-offs, Net of Recoveries	(1.9)	0	(0.3)
Balance at the end of year	9.3	4.7	5.4
Sales Return Reserve [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at the beginning of year	50.2	49	52.7
Charged as a Reduction in Revenues	65.4	53.2	35
Charged to Other Accounts	92.6	80.9	61.5
Used	(137)	(132.9)	(100.2)
Balance at the end of year	$ 71.2	$ 50.2	$ 49