Juniper Networks (JNPR) 10-Q 10 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 07, 2014
Document and Entity Information [Abstract]	'	'
Entity Registrant Name	'JUNIPER NETWORKS INC	'
Entity Central Index Key	'0001043604	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-14	'
Amendment Flag	'false	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
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	'	432,568,783

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net revenues:	'	'	'	'
Product	$809.50	$900.80	$2,614.70	$2,546.40
Service	316.4	284.8	910.8	849.1
Total net revenues	1,125.90	1,185.60	3,525.50	3,395.50
Cost of revenues:	'	'	'	'
Product	290	325.5	975.9	925
Service	121.1	113.6	366.5	332.7
Total cost of revenues	411.1	439.1	1,342.40	1,257.70
Gross margin	714.8	746.5	2,183.10	2,137.80
Operating expenses:	'	'	'	'
Research and development	253.2	264.6	772.7	784.5
Sales and marketing	249.2	269.5	780.6	792.7
General and administrative	55	61.4	190.5	169.1
Restructuring and other (credit) charges	-15	6	157.2	21
Total operating expenses	542.4	601.5	1,901	1,767.30
Operating income	172.4	145	282.1	370.5
Other (expense) income, net	-6.8	-7.5	326	-30.2
Income before income taxes	165.6	137.5	608.1	340.3
Income tax provision	62	38.4	172.8	52.3
Net income	$103.60	$99.10	$435.30	$288
Net income per share:	'	'	'	'
Basic, in dollars per share	$0.23	$0.20	$0.93	$0.57
Diluted, in dollars per share	$0.23	$0.19	$0.91	$0.56
Shares used in computing net income per share:	'	'	'	'
Basic (in shares)	448.4	501.5	468.1	503
Diluted (in shares)	454.8	508.6	477	510.7
Cash dividends declared per common stock	$0.10	$0	$0.10	$0

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net income	$103.60	$99.10	$435.30	$288
Available-for-sale securities:	'	'	'	'
Unrealized (losses) gains on available-for-sale securities, net of tax benefit (provision) of $2.0 and ($26.2) during the three and nine months ended September 30, 2014, respectively, and ($36.4) and ($40.4) for the corresponding periods of fiscal 2013, respectively	-4.4	65.2	44	70.8
Reclassification adjustment for realized net (gains) on available-for-sale securities included in net income, net of tax provision of $0.1 and $60.5 during the three and nine months ended September 30, 2014, respectively, and $0.1 and $0.3 for the corresponding periods of fiscal 2013, respectively	-0.2	-0.3	-104	-0.8
Unrealized (losses) gains on available-for-sale securities during the period, net of taxes	-4.6	64.9	-60	70
Cash flow hedges:	'	'	'	'
Unrealized (losses) gains on cash flow hedges, net of tax (provision) benefit of zero and ($1.3) during the three and nine months ended September 30, 2014, respectively, and $1.1 and $2.4 for the corresponding periods of fiscal 2013, respectively	-2.8	0.7	0.4	-1.8
Reclassification adjustment for realized net (gains) losses on cash flow hedges included in net income, net of tax provision (benefit) of $0.5 and $0.8 during the three and nine months ended September 30, 2014, respectively, and ($0.8) and ($0.3) for the corresponding periods of fiscal 2013, respectively	-1	0.6	-4.2	-0.9
Unrealized (losses) gains on cash flow hedges during the period, net of taxes	-3.8	1.3	-3.8	-2.7
Change in foreign currency translation adjustments	-7.7	4.1	-3.8	-5.4
Other comprehensive (loss) income, net of tax	-16.1	70.3	-67.6	61.9
Comprehensive income	$87.50	$169.40	$367.70	$349.90

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income Parentheticals (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Statement of Comprehensive Income [Abstract]	'	'	'	'
Tax (provision) benefit on change in unrealized gains on available-for-sale securities	$2	($36.40)	($26.20)	($40.40)
Tax (provision) benefit on reclassification adjustment for realized net gains on available-for-sale securities included in net income	0.1	0.1	60.5	0.3
Tax (provision) benefit on change in unrealized gains (losses) on cash flow hedges	0	1.1	-1.3	2.4
Tax (provision) benefit on reclassification adjustment for realized gains included in net income	$0.50	($0.80)	$0.80	($0.30)

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$1,615.90	$2,284
Short-term investments	299.5	561.9
Accounts receivable, net of allowances	617	578.3
Deferred tax assets, net	157.5	79.8
Prepaid expenses and other current assets	206.5	199.9
Assets held for sale	166.9	0
Total current assets	3,063.30	3,703.90
Property and equipment, net	888.8	882.3
Long-term investments	1,405.60	1,251.90
Restricted cash and investments	45.9	89.5
Purchased intangible assets, net	90.8	106.9
Goodwill	3,911.70	4,057.70
Other long-term assets	162.9	233.8
Total assets	9,569	10,326
Current liabilities:	'	'
Accounts payable	242.2	200.4
Accrued compensation	193.3	273.9
Deferred revenue	728.4	705.8
Other accrued liabilities	244.6	261.3
Liabilities held for sale	40.5	0
Total current liabilities	1,449	1,441.40
Long-term debt	1,348.90	999.3
Long-term deferred revenue	345.6	363.5
Long-term income taxes payable	154.2	114.4
Other long-term liabilities	80.9	105.2
Total liabilities	3,378.60	3,023.80
Commitments and contingencies (Note 17)	'	'
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; 438.1 shares and 495.2 shares issued and outstanding as of September 30, 2014 and December 31, 2013, respectively	0	0
Additional paid-in capital	9,157.10	9,868.90
Accumulated other comprehensive (loss) income	-3	64.6
Accumulated deficit	-2,963.70	-2,631.30
Total stockholders' equity	6,190.40	7,302.20
Total liabilities and stockholders' equity	$9,569	$10,326

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets Parentheticals (Unaudited) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Convertible preferred stock - par value	$0.00	$0.00
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	$0.00	$0.00
Common stock - shares authorized	1,000,000,000	1,000,000,000
Common stock - issued	438,100,000	495,200,000
Common stock - outstanding	438,100,000	495,200,000

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Cash flows from operating activities:	'	'
Net income	$435.30	$288
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Share-based compensation expense	185.4	180.7
Depreciation, amortization, and accretion	141.9	135.2
Restructuring and other (credit) charges	179.4	28.6
Deferred income taxes	-85.4	40.4
Gain on investments, net	-165.1	-7.8
Gain on legal settlement, net	-121.1	0
Excess tax benefits from share-based compensation	-8.8	-1.5
Loss on disposal of fixed assets	1.9	1.2
Changes in operating assets and liabilities, net of effects from acquisitions:	'	'
Accounts receivable, net	-33.2	-111
Prepaid expenses and other assets	-29.4	-67
Accounts payable	47.4	-1.1
Accrued compensation	-78.3	-88.6
Income taxes payable	86.1	-26.1
Other accrued liabilities	-124.5	-16.8
Deferred revenue	40.9	97.7
Net cash provided by operating activities	472.5	451.9
Cash flows from investing activities:	'	'
Purchases of property and equipment	-140.9	-183
Purchases of available-for-sale investments	-1,970.50	-1,351.60
Proceeds from sales of available-for-sale investments	1,918.70	860.4
Proceeds from maturities of available-for-sale investments	339	287.6
Purchases of trading investments	-3.5	-3.1
Proceeds from sales of privately-held investments	2.5	8.4
Purchases of privately-held investments	-12.3	-20.4
Payments for business acquisitions, net of cash and cash equivalents acquired	-27.1	-10
Purchase of licensed software	0	-10
Changes in restricted cash	45	0
Net cash provided by (used in) investing activities	150.9	-421.7
Cash flows from financing activities:	'	'
Proceeds from issuance of common stock	157.6	123.7
Purchases and retirement of common stock	-1,761	-332.1
Issuance of long-term debt, net	346.5	0
Payment for capital lease obligation	-0.4	-1.4
Customer financing arrangements	0.8	41.8
Excess tax benefits from share-based compensation	8.8	1.5
Payment of cash dividends	-43.8	0
Net cash used in financing activities	-1,291.50	-166.5
Net decrease in cash and cash equivalents	-668.1	-136.3
Cash and cash equivalents at beginning of period	2,284	2,407.80
Cash and cash equivalents at end of period	$1,615.90	$2,271.50

Basis_of_Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis of Presentation	'
	Basis of Presentation
	Basis of Presentation
	The unaudited Condensed Consolidated Financial Statements of Juniper Networks, Inc. (the "Company" or "Juniper") have been prepared in accordance with United States ("U.S.") generally accepted accounting principles (“U.S. GAAP”) for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The Condensed Consolidated Balance Sheet as of December 31, 2013, is derived from the audited Consolidated Financial Statements for the year ended December 31, 2013. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three and nine months ended September 30, 2014, are not necessarily indicative of the results that may be expected for the year ending December 31, 2014, or any future period. The information included in this Quarterly Report on Form 10-Q ("Report") should be read in conjunction with “Management's Discussion and Analysis of Financial Condition and Results of Operations,” “Risk Factors,” “Quantitative and Qualitative Disclosures About Market Risk,” and the Consolidated Financial Statements and footnotes thereto included in the Company's Annual Report on Form 10-K for the year ended December 31, 2013. Certain amounts in the prior year Condensed Consolidated Financial Statements contained in this Report have been reclassified to conform to the current year presentation.
	The preparation of the financial statements and related disclosures in accordance with U.S. GAAP requires the Company to make judgments, assumptions, and estimates that affect the amounts reported in the Condensed Consolidated Financial Statements and the accompanying notes. Actual results could differ materially from those estimates under different assumptions or conditions.
	In the first quarter of 2014, the Company announced an integrated operating plan ("IOP") to refocus the Company's strategy, optimize its structure, and improve operational efficiencies. In connection with the IOP, the Company realigned its organization into a One-Juniper structure which includes consolidating the Company's R&D and go-to-market functions to reduce complexity, increase clarity of responsibilities, and improve efficiency. As a result of these changes, the Company's consolidated business is considered to be one reportable segment. Future organizational changes, if any, could impact how the chief operating decision maker ("CODM") allocates resources and assesses performance. In fiscal 2013, the Company operated under two reportable segments: Platform Systems Division ("PSD") and Software Solutions Division ("SSD"). This change did not impact previously reported consolidated results of operations. See Note 14, Segments, for further discussion of the Company's segment reorganization.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies	'
	Summary of Significant Accounting Policies
	There have been no material changes to the Company's significant accounting policies compared to the accounting policies described in Note 2, Significant Accounting Policies, in Notes to Consolidated Financial Statements in Item 8 of Part II of the Annual Report on Form 10-K for the year ended December 31, 2013.
	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15 (Subtopic 205-40) - Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern ("ASU 2014-15") which provides guidance about management's responsibility to evaluate whether or not there is substantial doubt about the Company's ability to continue as a going concern and to provide related footnote disclosure. ASU 2014-15 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Early application is permitted. The adoption of this standard is not expected to have an 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 is not expected to 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. ASU 2014-09 is effective for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted. Accordingly, the ASU will be effective for the Company beginning fiscal year 2017. The Company is currently evaluating the impact of the adoption on its Consolidated Financial Statements.
	In April 2014, the FASB issued ASU No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-08") which raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. ASU 2014-08 is effective for annual periods beginning on or after December 15, 2014. Early adoption is permitted but only for disposals that have not been reported in financial statements previously issued. The Company has determined that this pronouncement would not have a material impact on the Company's financial position or results of operations.

Business_Combination

Business Combination	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Business Combination	'
	Business Combination
	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.
	The aggregate consideration of $28.7 million was allocated as follows: intangible assets of $17.8 million, recognized goodwill of $13.6 million, and net liabilities of $2.7 million. The goodwill recognized for the acquisition of WANDL was primarily attributable to expected synergies and is not deductible for U.S. federal income tax purposes.
	Additionally, under the terms of the purchase agreement, the Company assumed share-based awards for employees with a fair value of $34.9 million, which were granted in contemplation of future services and will be 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 nine months ended September 30, 2014 (in millions, except years):
		Weighted	Amount
		Average
		Estimated
		Useful
		Life
		(In Years)
	Existing technology	7	$	10.7
	Customer relationships	7	6
	Trade name	4	0.6
	Backlog	1	0.2
	Non-compete agreements	2	0.3
	Total	7	$	17.8
	The Company's Condensed Consolidated Financial Statements include the operating results of this business combination from the date of acquisition. Pro forma results of operations for this acquisition have not been presented as the financial impact to the Company's consolidated results of operations is not material.

Assets_Held_for_Sale

Assets Held for Sale	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Assets Held for Sale	'
	Assets Held for Sale
	On July 22, 2014, the Company entered into a definitive agreement to sell its Junos® Pulse product portfolio to an affiliate of Siris Capital, a private equity firm, for approximately $250.0 million, subject to certain working capital adjustments. The sale was completed on October 1, 2014 and the Company received total consideration of $228.1 million, of which $103.1 million was in cash, net of a $21.9 million working capital adjustment, and $125.0 million was in the form of an 18-month non-contingent interest bearing promissory note issued to the Company. The related assets and liabilities sold have been presented as held for sale in the Condensed Consolidated Balance Sheet as of September 30, 2014. The Company's sale of the Junos Pulse product portfolio is driven by product rationalization in connection with the Company's IOP.
	The following table presents the carrying value of the major components of assets and liabilities of Junos Pulse held for sale as of September 30, 2014 (in millions):
		As of
		September 30, 2014
	Assets:
	Goodwill(1)	$	159.8
	Intangible assets	6
	Other assets	1.1
	Total assets held for sale	$	166.9
	Liabilities:
	Deferred revenue	$	38.3
	Other liabilities	2.2
	Total liabilities related to assets held for sale	$	40.5

Cash_Equivalents_and_Investmen

Cash Equivalents and Investments	9 Months Ended
	Sep. 30, 2014
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 September 30, 2014 and December 31, 2013 (in millions):
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	As of September 30, 2014
	Fixed income securities:
	Asset-backed securities	$	310.3	$	—		$	(0.3	)	$	310
	Certificates of deposit	12.4		—			—			12.4
	Commercial paper	12.9		—			—			12.9
	Corporate debt securities	869.8		0.8			(0.8		)	869.8
	Foreign government debt securities	28.4		—			—			28.4
	Government-sponsored enterprise obligations	200.3		0.1			(0.2		)	200.2
	U.S. government securities	269.9		0.1			—			270
	Total fixed income securities	1,704.00		1			(1.3		)	1,703.70
	Money market funds	692		—			—			692
	Mutual funds	3.8		0.1			—			3.9
	Publicly-traded equity securities	2.4		—			(0.3		)	2.1
	Total available-for-sale securities	2,402.20		1.1			(1.6		)	2,401.70
	Trading securities in mutual funds(1)	16.7		—			—			16.7
	Total	$	2,418.90	$	1.1		$	(1.6	)	$	2,418.40
	Reported as:
	Cash equivalents	$	668.2	$	—		$	—		$	668.2
	Restricted investments	45.1		—			—			45.1
	Short-term investments	299.5		0.3			(0.3		)	299.5
	Long-term investments	1,406.10		0.8			(1.3		)	1,405.60
	Total	$	2,418.90	$	1.1		$	(1.6	)	$	2,418.40
	________________________________
	(1)	Balance includes the Company's non-qualified deferred compensation plan assets.
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	As of December 31, 2013
	Fixed income securities:
	Asset-backed securities	$	249.9	$	0.1		$	(0.1	)	$	249.9
	Certificates of deposit	27.6		—			—			27.6
	Commercial paper	6.9		—			—			6.9
	Corporate debt securities	813.6		2			(0.3		)	815.3
	Foreign government debt securities	10.7		—			—			10.7
	Government-sponsored enterprise obligations	306.2		0.1			(0.1		)	306.2
	U.S. government securities	303.3		0.1			(0.1		)	303.3
	Total fixed income securities	1,718.20		2.3			(0.6		)	1,719.90
	Money market funds	1,043.70		—			—			1,043.70
	Mutual funds	3.9		0.1			—			4
	Publicly-traded equity securities	12		104.5			(1.9		)	114.6
	Total available-for-sale securities	2,777.80		106.9			(2.5		)	2,882.20
	Trading securities in mutual funds(1)	15.4		—			—			15.4
	Total	$	2,793.20	$	106.9		$	(2.5	)	$	2,897.60
	Reported as:
	Cash equivalents	$	996.2	$	—		$	—		$	996.2
	Restricted investments	87.5		0.1			—			87.6
	Short-term investments	459		104.9			(2.0		)	561.9
	Long-term investments	1,250.50		1.9			(0.5		)	1,251.90
	Total	$	2,793.20	$	106.9		$	(2.5	)	$	2,897.60
	________________________________
	(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 September 30, 2014 (in millions):
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	Due in less than one year	$	297.9	$	0.2		$	—		$	298.1
	Due between one and five years	1,406.10		0.8			(1.3		)	1,405.60
	Total	$	1,704.00	$	1		$	(1.3	)	$	1,703.70
	The Company had 325 and 178 investments in an unrealized loss position as of September 30, 2014 and December 31, 2013, 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 September 30, 2014, the Company anticipates that it will recover the entire amortized cost basis of such available-for-sale debt securities and has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the three and nine months ended September 30, 2014 and September 30, 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 three and nine months ended September 30, 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 and $2.7 million, respectively that were recorded within other (expense) income, net, in the Condensed Consolidated Statements of Operations. There were no such charges during the three and nine months ended September 30, 2013.
During the nine months ended September 30, 2014, gross realized gains from available-for-sale securities were $166.3 million and gross realized losses were not material, excluding the impairment charge noted above. During the three months ended September 30, 2014, and during the three and nine months ended September 30, 2013, there were no material gross realized gains or losses from available-for-sale securities and there were no material gross realized gains or losses from trading securities during the three and nine months ended September 30, 2014 and September 30, 2013.
The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of September 30, 2014 and December 31, 2013 (in millions):
	Less than 12 Months					12 Months or Greater					Total
	Fair		Unrealized			Fair			Unrealized		Fair		Unrealized
	Value		Loss			Value			Loss		Value		Loss
As of September 30, 2014
Fixed income securities:
Asset-backed securities	$	237.2	$	(0.3	)	$	—		$	—	$	237.2	$	(0.3	)
Corporate debt securities	472.8		(0.8		)	—			—		472.8		(0.8		)
Foreign government debt securities(1)	15.9		—			—			—		15.9		—
Government-sponsored enterprise obligations	104.2		(0.2		)	—			—		104.2		(0.2		)
U.S. government securities(1)	21.7		—			—			—		21.7		—
Total fixed income securities	851.8		(1.3		)	—			—		851.8		(1.3		)
Publicly-traded equity securities	2.1		(0.3		)	—			—		2.1		(0.3		)
Total available-for-sale securities	$	853.9	$	(1.6	)	$	—		$	—	$	853.9	$	(1.6	)
________________________________
(1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of September 30, 2014.
	Less than 12 Months					12 Months or Greater					Total
	Fair		Unrealized			Fair			Unrealized		Fair		Unrealized
	Value		Loss			Value			Loss		Value		Loss
As of December 31, 2013
Fixed income securities:
Asset-backed securities(1)	$	153	$	(0.1	)	$	0.6		$	—	$	153.6	$	(0.1	)
Corporate debt securities(1)	156.1		(0.3		)	9.7			—		165.8		(0.3		)
Foreign government debt securities(2)	10		—			—			—		10		—
Government-sponsored enterprise obligations	123.1		(0.1		)	—			—		123.1		(0.1		)
U.S. government securities	119.7		(0.1		)	—			—		119.7		(0.1		)
Total fixed income securities	561.9		(0.6		)	10.3			—		572.2		(0.6		)
Publicly-traded equity securities	6.8		(1.9		)	—			—		6.8		(1.9		)
Total available-for-sale securities	$	568.7	$	(2.5	)	$	10.3		$	—	$	579	$	(2.5	)
________________________________
(1)	Balances 12 months or greater include investments that were in an immaterial unrealized loss position as of December 31, 2013.
(2)	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2013.
Restricted Cash and Investments
The Company classifies certain cash and investments as restricted cash and investments on its Condensed 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 September 30, 2014 and December 31, 2013, the carrying values of the Company's privately-held investments of $79.3 million and $57.2 million, respectively, were included in other long-term assets in the Condensed Consolidated Balance Sheets. As of September 30, 2014, the carrying value of the privately-held debt securities was $42.3 million. For the nine months ended September 30, 2014, the Company recorded $10.0 million in other comprehensive income for unrealized gains associated with its privately-held debt securities. During the three months ended September 30, 2014, and during the three and nine months ended September 30, 2013, there were no unrealized gains associated with its privately-held debt securities.
The Company reviews its investments to identify and evaluate investments that have an indication of possible impairment. The Company adjusts the carrying value of 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 three and nine months ended September 30, 2014, the Company determined that certain privately-held investments were other than temporarily impaired, resulting in impairment charges of $1.1 million that were recorded within other (expense) income, net in the Condensed Consolidated Statements of Operations. For the three and nine months ended September 30, 2013, the Company recorded impairment charges for certain privately-held investments of $2.1 million and $2.5 million, respectively, within other (expense) income, net in the Condensed Consolidated Statements of Operations.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2014
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 Condensed Consolidated Balance Sheets (in millions):
		Fair Value Measurements at September 30, 2014 Using:
		Quoted Prices in		Significant Other			Significant Other
		Active Markets For		Observable			Unobservable
		Identical Assets		Remaining Inputs			Remaining Inputs
		(Level 1)		(Level 2)			(Level 3)		Total
	Assets measured at fair value:
	Available-for-sale securities:
	Asset-backed securities	$	—	$	310		$	—	$	310
	Certificates of deposit	—		12.4			—		12.4
	Commercial paper	—		12.9			—		12.9
	Corporate debt securities	—		869.8			—		869.8
	Foreign government debt securities	—		28.4			—		28.4
	Government-sponsored enterprise obligations	—		200.2			—		200.2
	Money market funds(1)	692		—			—		692
	Mutual funds(2)	3.9		—			—		3.9
	Publicly-traded equity securities	2.1		—			—		2.1
	U.S. government securities	243		27			—		270
	Total available-for-sale securities	941		1,460.70			—		2,401.70
	Trading securities in mutual funds(3)	16.7		—			—		16.7
	Privately-held debt securities	—		—			42.3		42.3
	Derivative assets:
	Foreign exchange contracts	—		1.2			—		1.2
	Total assets measured at fair value	$	957.7	$	1,461.90		$	42.3	$	2,461.90
	Liabilities measured at fair value:
	Derivative liabilities:
	Foreign exchange contracts	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total liabilities measured at fair value	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total assets measured at fair value, reported as:
	Cash equivalents	$	650.8	$	17.4		$	—	$	668.2
	Restricted investments	45.1		—			—		45.1
	Short-term investments	98.4		201.1			—		299.5
	Long-term investments	163.4		1,242.20			—		1,405.60
	Prepaid expenses and other current assets	—		1.2			—		1.2
	Other long-term assets	—		—			42.3		42.3
	Total assets measured at fair value	$	957.7	$	1,461.90		$	42.3	$	2,461.90
	Total liabilities measured at fair value, reported as:
	Other accrued liabilities	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total liabilities measured at fair value	$	—	$	(1.8	)	$	—	$	(1.8	)
	________________________________
	(1)	Balance includes $41.3 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 restricted investments measured at fair market value related to the Company's India Gratuity Trust.
	(3)	Balance relates to investments measured at fair value related to the Company's non-qualified deferred compensation plan assets.
		Fair Value Measurements at December 31, 2013 Using:
		Quoted Prices in		Significant Other			Significant Other
		Active Markets For		Observable			Unobservable
		Identical Assets		Remaining Inputs			Remaining Inputs
		(Level 1)		(Level 2)			(Level 3)		Total
	Assets measured at fair value:
	Available-for-sale securities:
	Asset-backed securities	$	—	$	249.9		$	—	$	249.9
	Certificates of deposit	—		27.6			—		27.6
	Commercial paper	—		6.9			—		6.9
	Corporate debt securities	—		815.3			—		815.3
	Foreign government debt securities	—		10.7			—		10.7
	Government-sponsored enterprise obligations	—		306.2			—		306.2
	Money market funds(1)	1,043.70		—			—		1,043.70
	Mutual funds(2)	4		—			—		4
	Publicly-traded equity securities	114.6		—			—		114.6
	U.S. government securities	197.2		106.1			—		303.3
	Total available-for-sale securities	1,359.50		1,522.70			—		2,882.20
Trading securities in mutual funds(3)	15.4		—			—		15.4
Privately-held debt securities	—		—			28.1		28.1
Derivative assets:
Foreign exchange contracts	—		3			—		3
Total assets measured at fair value	$	1,374.90	$	1,525.70		$	28.1	$	2,928.70
Liabilities measured at fair value:
Derivative liabilities:
Foreign exchange contracts	$	—	$	(0.7	)	$	—	$	(0.7	)
Total liabilities measured at fair value	$	—	$	(0.7	)	$	—	$	(0.7	)
Total assets measured at fair value, reported as:
Cash equivalents	$	965.1	$	31.1		$	—	$	996.2
Restricted investments	87.6		—			—		87.6
Short-term investments	246.5		315.4			—		561.9
Long-term investments	75.7		1,176.20			—		1,251.90
Prepaid expenses and other current assets	—		3			—		3
Other long-term assets	—		—			28.1		28.1
Total assets measured at fair value	$	1,374.90	$	1,525.70		$	28.1	$	2,928.70
Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—	$	(0.7	)	$	—	$	(0.7	)
Total liabilities measured at fair value	$	—	$	(0.7	)	$	—	$	(0.7	)
________________________________
(1)	Balance includes $83.6 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 restricted investments measured at fair market value related to the Company's India Gratuity Trust.
(3)	Balance relates to 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 three and nine months ended September 30, 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 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 three and nine months ended September 30, 2014, there were purchases of $0.2 million and $4.6 million respectively, related to our 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, 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 identified 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 September 30, 2014, the Company had no significant assets 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, representing the difference between the net book value and the fair value, are recorded to other (expense) income, net in the Condensed Consolidated Statements of Operations.
As of September 30, 2014 and December 31, 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 September 30, 2014 and December 31, 2013, the estimated fair value of the Company's long-term debt in the Condensed Consolidated Balance Sheets was approximately $1,432.7 million and $1,023.5 million, respectively, based on observable market inputs (Level 2).

Derivative_Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2014
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
		September 30,		December 31,
		2014		2013
	Cash flow hedges	$	144.4	$	137.6
	Non-designated derivatives	94.7		144.4
	Total	$	239.1	$	282
	Cash Flow Hedges
	The Company uses foreign currency forward or option contracts to hedge certain forecasted foreign currency transactions relating to cost of services and operating expenses. The derivatives are intended to hedge the U.S. Dollar equivalent of the Company's planned cost of services and operating expenses denominated in certain 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. 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 cost 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, in its Condensed 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.
	See Note 6, Fair Value Measurements, for the fair values of the Company's derivative instruments in the Condensed Consolidated Balance Sheets.
	During the three and nine months ended September 30, 2014, the Company recognized a loss of $2.8 million and a gain of $1.7 million, respectively, in accumulated other comprehensive (loss) income for the effective portion of its derivative instruments and reclassified a gain of $1.5 million and $5.0 million, respectively, from other comprehensive income to operating expense in the Condensed Consolidated Statements of Operations. During the three and nine months ended September 30, 2013, the Company recognized a loss of $0.4 million and $4.2 million, respectively, in accumulated other comprehensive loss for the effective portion of its derivative instruments and reclassified a loss of $1.4 million and a gain of $0.6 million, respectively, from other comprehensive (loss) income to operating expense in the Condensed Consolidated Statements of Operations.
	The ineffective portion of the Company's derivative instruments recognized in its Condensed Consolidated Statements of Operations was not material during the three and nine months ended September 30, 2014 and September 30, 2013.
	Non-Designated Derivatives
	The Company also uses foreign currency forward contracts to mitigate variability in gains and losses generated from the remeasurement of certain monetary assets and liabilities denominated in foreign currencies. These derivatives were not designated for special hedge accounting treatment. These derivatives are carried at fair value with changes recorded in other (expense) income, net, in the Condensed Consolidated Statements of Operations. Changes in the fair value of these derivatives are largely offset by remeasurement of the underlying assets and liabilities. Cash flows from such derivatives are classified as operating activities. The derivatives have maturities within two months.
	During the three and nine months ended September 30, 2014, the Company recognized net losses of $0.3 million and $3.3 million, respectively, on non-designated derivative instruments within other expense, net, in its Condensed Consolidated Statements of Operations. During the three and nine months ended September 30, 2013, the Company recognized net gain of $0.9 million and $1.0 million, respectively, on non-designated derivative instruments within other (expense) income, net, in its Condensed Consolidated Statements of Operations.
	Offsetting of Derivatives
	The Company presents its derivative assets and derivative liabilities on a gross basis in the Condensed 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 September 30, 2014 and December 31, 2013, 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_Intangi

Goodwill and Purchased Intangible Assets	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Purchased Intangible Assets	'
	Goodwill and Purchased Intangible Assets
	Goodwill
	The following table presents goodwill activity during the nine months ended September 30, 2014 (in millions):
	Balance as of December 31, 2013	$	4,057.70
	Additions due to business combination	13.6
	Goodwill reclassified to assets held for sale	(159.8		)
	Tax reserve adjustment	0.2
	Balance as of September 30, 2014	$	3,911.70
	The additions to goodwill were based on the purchase price allocation of the acquisition completed during the first quarter of 2014. There were no impairments to goodwill during the three and nine months ended September 30, 2014 and September 30, 2013.
	Purchased Intangible Assets
	The Company’s purchased intangible assets were as follows (in millions):
		Gross			Accumulated			Impairments and			Net
					Amortization			Other Charges (1)
	As of September 30, 2014
	Intangible assets with finite lives:
	Technologies and patents	$	592		$	(477.8	)	$	(35.7	)	$	78.5
	Customer contracts, support agreements, and	80.3			(65.8		)	(3.0		)	11.5
	related relationships
	Other	19.9			(19.1		)	—			0.8
	Total purchased intangible assets	$	692.2		$	(562.7	)	$	(38.7	)	$	90.8
	As of December 31, 2013
	Intangible assets with finite lives:
	Technologies and patents	$	581.4		$	(453.4	)	$	(30.5	)	$	97.5
	Customer contracts, support agreements, and	74.3			(62.7		)	(2.2		)	9.4
	related relationships
	Total purchased intangible assets	$	655.7		$	(516.1	)	$	(32.7	)	$	106.9
	________________________________
	(1) Balance includes $6.0 million of unamortized intangible assets related to Junos Pulse that have been reclassified to assets held for sale.
	Intangible assets to be disposed of as a result of the Junos Pulse product portfolio disposition were included in assets held for sale within the Condensed Consolidated Balance Sheets as of September 30, 2014 and accordingly, amortization of the assets was stopped as of the date they were deemed to be held for sale.
	The following table presents the amortization of intangible assets included in the Condensed Consolidated Statements of Operations (in millions):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Cost of revenues	$	7.1		$	6.5		$	23.7		$	19.3
	Operating expenses:
	Sales and marketing	1.1			0.8			3.2			2.6
	General and administrative	0.3			0.3			0.9			0.9
	Total operating expenses	1.4			1.1			4.1			3.5
	Total	$	8.5		$	7.6		$	27.8		$	22.8
	There were no impairment charges related to purchased intangible assets during the three and nine months ended September 30, 2014 and September 30, 2013.
	As of September 30, 2014, the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions):
	Years Ending December 31,	Amount
	Remainder of 2014	$	8.5
	2015	32.1
	2016	20.8
	2017	13
	2018	6.1
	Thereafter	10.3
	Total	$	90.8

Other_Financial_Information

Other Financial Information	9 Months Ended
	Sep. 30, 2014
Other Financial Information [Abstract]	'
Other Financial Information	'
	Other Financial Information
	Inventories
	The Company purchases and holds inventory to help ensure adequate component supplies over the life of the underlying products. The majority of the Company's inventory is production components. Inventories are reported both within prepaid expenses and other current assets and other long-term assets in the Condensed Consolidated Balance Sheets. Total inventories consisted of the following (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Production materials	$	35.6		$	51.3
	Finished goods	15			1.4
	Inventories	$	50.6		$	52.7
	The Company recorded charges in cost of revenues of $15.5 million for the nine months ended September 30, 2014, related to the acceleration of the end-of-life of certain products in connection with the 2014 Restructuring Plan discussed in Note 10, Restructuring and Other Charges, and no similar charges for the three months ended September 30, 2014.
	Other Long-Term Assets
	Other long-term assets consisted of the following (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Privately-held investments	$	79.3		$	57.2
	Licensed software	9.4			90.4
	Federal income tax receivable	20			20
	Financed customer receivable	18.2			19.9
	Inventory	6.8			15.2
	Prepaid costs, deposits, and other	29.2			31.1
	Other long-term assets	$	162.9		$	233.8
	In connection with the 2014 Restructuring Plan discussed in Note 10, Restructuring and Other Charges, the Company reviewed its product portfolio and determined to cease development of the application delivery controller software technology licensed in July 2012. As a result, the Company recognized a charge of $84.7 million recorded within operating expenses in the Condensed Consolidated Statements of Operations during the nine months ended September 30, 2014. There were no revenues associated with this technology.
	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 Condensed Consolidated Balance Sheets. Changes in the Company’s warranty reserve during the nine months ended September 30, 2014 were as follows (in millions):
	Balance as of December 31, 2013	$	28
	Provisions made during the period	21.9
	Actual costs incurred during the period	(21.3		)
	Warranty reclassified to liabilities held for sale	(0.5		)
	Balance as of September 30, 2014	$	28.1
	Deferred Revenue
	Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Deferred product revenue:
	Undelivered product commitments and other product deferrals	$	166.5		$	184.9
	Distributor inventory and other sell-through items	113			118.7
	Deferred gross product revenue	279.5			303.6
	Deferred cost of product revenue	(57.0		)	(58.6		)
	Deferred product revenue, net	222.5			245
	Deferred service revenue	851.5			824.3
	Total	$	1,074.00		$	1,069.30
	Reported as:
	Current	$	728.4		$	705.8
	Long-term	345.6			363.5
	Total	$	1,074.00		$	1,069.30
	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. 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):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Interest income	$	2.7		$	2.3		$	6.9		$	6.1
	Interest expense	(16.9		)	(14.2		)	(50.2		)	(43.4		)
	Net gain on legal settlement	0.8			—			196.1			—
	(Loss) gain on investments	(1.9		)	4			165.1			7.8
	Other	8.5			0.4			8.1			(0.7		)
	Other (expense) income, net	$	(6.8	)	$	(7.5	)	$	326		$	(30.2	)
	Interest income primarily includes interest earned on the Company’s cash, cash equivalents, and investments. Interest expense primarily includes interest, net of capitalized interest expense, from long-term debt and customer financing arrangements. Other typically consists of foreign exchange gains and losses and other non-operational income and expense items.
	During the nine months ended September 30, 2014, the Company entered into a settlement agreement with Palo Alto Networks ("PAN") resolving 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. Under the terms of the settlement, PAN made a one-time payment to the Company of $75.0 million in cash and issued PAN common stock and warrants to the Company. The fair value of the PAN common stock and warrants at the date of receipt was included in the net realized gain. All such PAN securities were sold in the third quarter of 2014, and the Company recorded an additional $0.8 million gain during the three months ended September 30, 2014.
	Other (expense) income, net, during the nine months ended September 30, 2014, was also comprised of a gain of $163.0 million, related to the sale of investments which were converted from privately-held investments to publicly-traded equity upon IPO and subsequently sold.
	During the three and nine months ended September 30, 2013, net gain on investments was primarily comprised of a gain of $3.6 million and $4.9 million, respectively, related to the Company's privately-held investments.

Restructuring_and_Other_Charge

Restructuring and Other Charges	9 Months Ended
	Sep. 30, 2014
Restructuring Charges [Abstract]	'
Restructuring and Other Charges	'
	Restructuring and Other Charges
	The following table presents restructuring and other charges included in cost of revenues and restructuring and other (credit) charges in the Condensed Consolidated Statements of Operations (in millions):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Severance	$	7.1		$	3.8		$	45.6		$	9
	Facilities	(25.0		)	(0.8		)	12.8			9.5
	Contract terminations	—			1.8			2.3			2.8
	Total restructuring charges	(17.9		)	4.8			60.7			21.3
	Asset impairment and write-downs	2.9			7.3			118.7			7.3
	Total restructuring and other (credit) charges	$	(15.0	)	$	12.1		$	179.4		$	28.6
	Reported as:
	Cost of revenues	$	—		$	6.1		$	22.2		$	7.6
	Restructuring and other (credit) charges	(15.0		)	6			157.2			21
	Total	$	(15.0	)	$	12.1		$	179.4		$	28.6
	Restructuring and other (credit) charges noted above are based on the Company's 2014 Restructuring Plan and Other Restructuring Plans that were committed to by management. Any changes in the estimates of executing the approved plans are reflected in the Company's results of operations.
	2014 Restructuring Plan
	In connection with IOP announced 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 consists of workforce reductions, facility consolidations and closures, asset write-downs, contract terminations and other charges.
	During the three months ended September 30, 2014, the Company recorded $7.1 million of severance costs, a benefit of $25.0 million of facility consolidation and closures, and $2.9 million of asset write-downs, that were recorded to restructuring and other (credit) charges in the Condensed Consolidated Statements of Operations.
	During the three months ended September 30, 2014, the Company with the consent of its landlord and the administrative agent to its lienholder, assigned certain of its real property leases, totaling approximately 0.4 million square feet, some of which the Company has already ceased the use of in the second quarter, 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 a 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 (credit) charges in the Condensed Consolidated Statements of Operations. As a result of the lease assignments, the Company recorded a benefit of approximately $25.0 million, which included a reversal of previously recorded restructuring liability and additional charges relating to facility consolidation activities, in the third quarter of 2014.
	During the nine months ended September 30, 2014, the Company recorded $45.0 million of severance costs, $12.6 million of facility consolidation and closures costs, $84.7 million of impairment charges related to licensed software, $11.8 million of asset write-downs, and $2.3 million of charges related to contract terminations, which were recorded to restructuring and other (credit) charges in the Condensed Consolidated Statements of Operations. The Company also recorded inventory write-downs of $15.5 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 Condensed Consolidated Statements of Operations during the nine months ended September 30, 2014.
	In connection with the 2014 Restructuring Plan, the Company expects to record aggregate future charges of approximately $7.0 million to $9.0 million allocated to the following restructuring activities: $4.0 million to $5.0 million for severance, $2.0 million to $3.0 million for facility consolidations or closures, and up to $1.0 million for contract terminations and other charges.
	Other Restructuring Plans
	Restructuring plans initiated by the Company in fiscal 2013, 2012, and 2011 have been substantially completed as of September 30, 2014. The Company does not expect to record significant future charges under these restructuring plans.
	Restructuring Liability
	Restructuring liabilities are reported within other accrued liabilities and other long-term liabilities in the Condensed Consolidated Balance Sheets. The following table provides a summary of changes in the restructuring liability related to the Company's plans during the nine months ended September 30, 2014 (in millions):
		December 31,			Charges			Cash			Non-cash			September 30,
		2013						Payments			Settlements and			2014
											Other
	Severance	$	5.6		$	45.6		$	(40.9	)	$	(1.0	)	$	9.3
	Facilities	5.1			12.8			(17.5		)	8.9			9.3
	Contract terminations and other	7.1			2.3			(8.3		)	(0.9		)	0.2
	Total	$	17.8		$	60.7		$	(66.7	)	$	7		$	18.8
	As of September 30, 2014, the Company's restructuring liability was $18.8 million, of which $9.5 million is related to severance and other charges expected to be settled by January 2015. The remaining $9.3 million related to facility closures is expected to be paid through March 2018.

LongTerm_Debt_and_Financing

Long-Term Debt and Financing	9 Months Ended
	Sep. 30, 2014
Debt Instruments [Abstract]	'
Long-Term Debt and Financing	'
	Long-Term Debt and Financing
	Long-Term Debt
	The following table summarizes the Company's long-term debt (in millions, except percentages):
		As of September 30, 2014
		Amount			Effective Interest
					Rates
	Senior notes:
	3.10% fixed-rate notes, due 2016 ("2016 Notes")	$	300		3.25	%
	4.60% fixed-rate notes, due 2021 ("2021 Notes")	300			4.69	%
	4.50% fixed-rate notes, due 2024 ("2024 Notes")	350			4.63	%
	5.95% fixed-rate notes, due 2041 ("2041 Notes")	400			6.03	%
	Total senior notes	1,350.00
	Unaccreted discount	(1.1		)
	Total	$	1,348.90
	In February 2014, the Company issued $350.0 million aggregate principal amount of 4.50% senior notes due 2024. The 2024 Notes are senior unsecured obligations and rank equally with all of the Company's other existing and future senior unsecured indebtedness. Interest on the 2024 Notes is payable in cash semiannually. The Company may redeem the 2024 Notes, at any time in whole or from time to time in part, subject to a make-whole premium, and in the event of a change in control, the holders of the 2024 Notes may require the Company to repurchase for cash all or part of the 2024 Notes at a purchase price equal to 101% of the aggregate principal amount, plus accrued and unpaid interest, if any. The indenture that governs the 2024 Notes also contains various covenants, including limitations on the Company's ability to incur liens or enter into sale-leaseback transactions over certain dollar thresholds.
	The effective interest rates for the 2016 Notes, 2021 Notes, 2024 Notes, and 2041 Notes (collectively the “Notes”) include the interest on the Notes, accretion of the discount, and amortization of issuance costs. As of September 30, 2014, the Company was in compliance with all of its covenants in the indentures governing the Company's 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 September 30, 2014, 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. The factored accounts receivable are isolated from the Company and put beyond the reach of the Company's creditors, even in the event of bankruptcy. The Company does not maintain effective control over the transferred assets through obligations or rights to redeem, transfer, or repurchase the receivables after they have been transferred.
	Pursuant to the financing arrangements for the sale of receivables, the Company sold net receivables of $92.8 million and $241.4 million during the three months ended September 30, 2014 and September 30, 2013, respectively, and $429.2 million and $607.1 million during the nine months ended September 30, 2014 and September 30, 2013, respectively.
	The Company received cash proceeds from the financing provider of $128.9 million and $210.8 million during the three months ended September 30, 2014 and September 30, 2013, respectively, and $473.3 million and $579.2 million during the nine months ended September 30, 2014 and September 30, 2013, respectively. As of September 30, 2014 and December 31, 2013, the amounts owed to the Company by the financing provider were $146.2 million and $189.8 million, respectively, and were recorded in accounts receivable on the Condensed 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 four years. The Company is liable for the aggregate unpaid payments to the third-party financing company in the event of customer default. As of September 30, 2014, 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 $22.1 million as of September 30, 2014.
	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 September 30, 2014 and December 31, 2013, the estimated cash received from the financing provider not recognized as revenue was $59.5 million and $62.3 million, respectively.

Equity

Equity	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Equity	'
	Equity
	Cash Dividends on Shares of Common Stock
	On July 22, 2014, the Company declared a quarterly cash dividend of $0.10 per share of common stock, or $43.8 million in the aggregate, to stockholders of record on September 2, 2014 which was paid on September 23, 2014. 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 September 30, 2014.
	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 through the end of the first quarter of 2015, including $1.2 billion to be used pursuant to an accelerated share repurchase program ("2014 Stock Repurchase Program"). The $2.1 billion authorization replaced the $1.0 billion stock repurchase authorization approved by the Board in July 2013 ("2013 Stock Repurchase Program").
	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. During the three months ended March 31, 2014, the Company made an up-front payment of $1.2 billion pursuant to the ASR and received and retired an initial 33.3 million shares ("Initial Shares") of the Company’s common stock for an aggregate price of $900.0 million based on the market value of the Company’s common stock on the date of the transaction. The payment for the Initial Shares was accounted for as a reduction to stockholders' equity in the Condensed Consolidated Balance Sheets. On July 23, 2014, the ASR was completed and an additional 16.0 million shares for the remaining $300.0 million was received from the financial institutions for a total of 49.3 million shares of the Company's common stock, which resulted in a volume weighted average repurchase price, less an agreed upon discount, of $24.35 per share. The 16.0 million shares received were retired during the three months ended September 30, 2014. Retired shares return to authorized but unissued shares of common stock.
	Subsequent to the completion of the ASR, the Company repurchased and retired approximately 23.5 million shares of its common stock under the 2014 Stock Repurchase Program at an average price of $23.44 per share for an aggregate purchase price of $550.0 million during the three months ended September 30, 2014. During the three and nine months ended September 30, 2013, the Company repurchased and retired approximately 4.4 million and 17.0 million shares of its common stock, respectively, at an average price of $20.92 and $19.32 per share, respectively, for an aggregate purchase price of $92.9 million and $328.4 million, respectively.
	As of September 30, 2014, there was $350.0 million of authorized funds remaining under the 2014 Stock Repurchase Program. In October 2014, the Board authorized a $1.3 billion increase to the 2014 Stock Repurchase Program. The Company has announced its intention to repurchase an additional $1.5 billion of its common stock before the end of the second quarter of 2015, as part of its three year capital return 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. Repurchases associated with tax withholdings were not significant during the three and nine months ended September 30, 2014 and September 30, 2013.
	Future stock repurchases under the Company’s stock repurchase program will be subject to a review of the circumstances at that time and will be made from time to time in private transactions or open market purchases as permitted by securities laws and other legal requirements.
	See Note 18, Subsequent Events, for discussion of the Company's stock repurchase activity subsequent to September 30, 2014.
	Accumulated Other Comprehensive Income, Net of Tax
	The components of accumulated other comprehensive income, net of related taxes, during the nine months ended September 30, 2014 were as follows (in millions):
		Unrealized			Unrealized			Foreign			Total
		Gains (Losses)			Gains (Losses)			Currency
		on Available-for-			on Cash Flow			Translation
		Sale Securities(1)			Hedges(2)			Adjustments
	Balance as of December 31, 2013	$	66.2		$	2.2		$	(3.8	)	$	64.6
	Other comprehensive gain before reclassifications	44			0.4			(3.8		)	40.6
	Amount reclassified from accumulated other	(104.0		)	(4.2		)	—			(108.2		)
	comprehensive income
	Net other comprehensive loss	(60.0		)	(3.8		)	(3.8		)	(67.6		)
	Balance as of September 30, 2014	$	6.2		$	(1.6	)	$	(7.6	)	$	(3.0	)
	________________________________
	(1)	The reclassifications out of accumulated other comprehensive income during the nine months ended September 30, 2014 for realized gains on available-for-sale securities of $104.0 million are included in other (expense) income, net, in the Condensed Consolidated Statements of Operations.
	(2)	The reclassifications out of accumulated other comprehensive income during the nine months ended September 30, 2014 for realized gains on cash flow hedges are included within cost of revenues of $0.4 million, research and development of $1.3 million, sales and marketing of $1.6 million, and general and administrative of $0.9 million for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.

Employee_Benefit_Plans

Employee Benefit Plans	9 Months Ended
	Sep. 30, 2014
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 2006 Equity Incentive Plan (the “2006 Plan”), the 2000 Nonstatutory Stock Option Plan (the “2000 Plan”), the Amended and Restated 1996 Stock Plan (the “1996 Plan”), various equity incentive plans assumed through acquisitions, and the 2008 Employee Stock Purchase Plan (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 2006 Plan was adopted and approved by the Company’s stockholders in May 2006. To date, the Company's stockholders have approved a share reserve of 149.5 million shares of common stock plus the addition of any shares subject to options under the 2000 Plan and the 1996 Plan that were outstanding as of May 18, 2006, and that subsequently expire unexercised, up to a maximum of an additional 75.0 million shares. As of September 30, 2014, an aggregate of 30.3 million shares were subject to currently outstanding equity awards under the 2006 Plan, the 2000 Plan, and the 1996 Plan. As of September 30, 2014, 45.3 million shares were available for future issuance under the 2006 Plan and no shares were available for future issuance under either the 2000 Plan or the 1996 Plan.
	The ESPP was adopted and approved by the Company's stockholders in May 2008. To date, the Company's stockholders have approved a share reserve of 19.0 million shares of the Company's common stock for issuance under this plan. 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 September 30, 2014, approximately 15.7 million shares have been issued and 3.3 million shares remain available for future issuance under the ESPP.
	In connection with certain past acquisitions, the Company assumed stock options, RSUs, RSAs and PSAs under the assumed stock plans of the acquired companies and exchanged the assumed awards for the Company's stock options, RSUs, RSAs and PSAs, respectively. No new stock options, RSUs, RSAs and PSAs can be granted under these plans. As of September 30, 2014, stock options, RSUs, RSAs and PSAs representing approximately 4.7 million shares of common stock were outstanding under all awards assumed through the Company's acquisitions.
	Stock Option Activities
	The following table summarizes the Company’s stock option activity and related information as of and for the nine months ended September 30, 2014 (in millions, except for per share amounts and years):
		Outstanding Options
		Number of Shares			Weighted Average				Weighted Average		Aggregate
					Exercise Price				Remaining		Intrinsic
					per Share				Contractual Term		Value
									(In Years)
	Balance as of December 31, 2013	23.1			$	25.15
	Canceled	(0.6	)		30.34
	Exercised	(5.2	)		19.95
	Expired	(5.8	)		28.68
	Balance as of September 30, 2014	11.5			$	25.46			2.1		$	25.7
	As of September 30, 2014:
	Vested and expected-to-vest options	11.4			$	25.6			2.1		$	24.3
	Exercisable options	10.5			$	26.4			1.8		$	15.7
	The aggregate intrinsic value represents the difference between the Company’s closing stock price on the last trading day of the period, which was $22.15 per share as of September 30, 2014, 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 exercise and the exercise price of each option, was $3.4 million and $32.0 million for the three and nine months ended September 30, 2014, respectively.
	Restricted Stock Unit, Restricted Stock Award, and Performance Share Award Activities
	The following table summarizes the Company’s RSU, RSA, and PSA activity and related information as of and for the nine months ended September 30, 2014 (in millions, except per share amounts and years):
		Outstanding RSUs, RSAs, and PSAs
		Number of Shares			Weighted Average				Weighted Average		Aggregate
					Grant-Date Fair				Remaining		Intrinsic
					Value per Share				Contractual Term		Value
									(In Years)
	Balance as of December 31, 2013	25.4			$	23.44
	RSUs granted (1)(4)	8.8			22.98
	RSUs assumed (2)	0.4			22.66
	RSAs assumed (2)	0.9			22.66
	PSAs granted (3)(4)	0.8			25.59
	PSAs assumed (2)	0.2			22.66
	RSUs vested	(6.0	)		23.4
	RSAs vested	(1.1	)		19.59
	PSAs vested	(1.0	)		36.77
	RSUs canceled	(2.2	)		21.81
	PSAs canceled	(2.7	)		31.29
	Balance as of September 30, 2014	23.5			22.11				1.3		$	520.8
	________________________________
	(1)	Includes service-based and market-based RSUs granted under the 2006 Plan according to its terms.
	(2)	RSUs, RSAs, and PSAs assumed in connection with the acquisition of WANDL.
	(3)	The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to these PSAs that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.4 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 0.8 million shares.
	(4)	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. On July 22, 2014, the Company declared a cash dividend of $0.10 per share of common stock, or $43.8 million in the aggregate, to stockholders of record on September 2, 2014, which was paid on September 23, 2014.
	Employee Stock Purchase Plan
	The ESPP is implemented in a series of offering periods, each currently six months in duration, or such other period as determined by the Board. Employees purchased 1.4 million and 2.9 million shares of common stock through the ESPP at an average exercise price of $20.01 and $19.30 per share for the three and nine months ended September 30, 2014, respectively, and 1.5 million and 3.3 million shares at an average per share price of $18.42 and $16.53 for the three and nine months ended September 30, 2013, respectively.
	Valuation Assumptions
	There were no market-based RSU grants during the three months ended September 30, 2014 or the three and nine months ended September 30, 2013. The weighted-average assumptions used and the resulting estimates of fair value for ESPP and market-based RSUs during the three and nine months ended September 30, 2014 and September 30, 2013 were as follows:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	ESPP (1):
	Volatility	27%		35%		30%		36%
	Risk-free interest rate	0.10%		0.10%		0.10%		0.10%
	Expected life (years)	0.5		0.5		0.5		0.5
	Dividend yield	1.80%		—		1.00%		—
	Weighted-average fair value per share	$5.13		$5.47		$5.72		$5.54
	Market-based RSUs (2):
	Volatility	—		—		36%		—
	Risk-free interest rate	—		—		1.60%		—
	Dividend yield	—		—		0% - 1.5%		—
	Weighted-average fair value per share	—		—		$18.28		—
________________________________
(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 a Monte Carlo valuation methodology. 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 Condensed Consolidated Statements of Operations (in millions):
	Three Months Ended September 30,								Nine Months Ended September 30,
	2014				2013				2014			2013
Cost of revenues - Product	$	1.3			$	1.4			$	3.9		$	3.5
Cost of revenues - Service	3.6				3.4				10.7			11.5
Research and development	37.1				36.6				100.8			93.2
Sales and marketing	15.9				20.4				44.9			53
General and administrative	7.4				7.5				25.1			19.5
Total	$	65.3			$	69.3			$	185.4		$	180.7
The following table summarizes share-based compensation expense by award type (in millions):
	Three Months Ended September 30,								Nine Months Ended September 30,
	2014				2013				2014			2013
Stock options	$	3.2			$	7.7			$	12		$	24.9
RSUs, RSAs, and PSAs	58.2				57.7				161.9			144
ESPP	3.9				3.9				11.5			11.8
Total	$	65.3			$	69.3			$	185.4		$	180.7
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 September 30, 2014 (in millions, except years):
	Unrecognized				Weighted Average
	Compensation Cost				Period
					(In Years)
Stock options	$	15.9			1.5
RSUs, RSAs, and PSAs	$	302.8			1.9

Segments

Segments	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segments	'
	Segments
	In connection with the IOP, the Company realigned its organization into a One-Juniper structure which includes consolidating the Company's R&D and go-to-market functions to reduce complexity, increase clarity of responsibilities, and improve efficiency. As a result of these changes, the consolidated business is considered to be one reportable segment and operating segment, consistent with how the Company’s CODM views the business, allocates resources, and assesses the performance of the Company. Future organizational changes, if any, could impact how the CODM allocates resources and assesses performance.
	The Company continues to sell its high-performance network products and service offerings across routing, switching, and security to service provider and enterprise markets.
	The following table presents net revenues by product and service (in millions):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Routing	$	533.2	$	609	$	1,700.80	$	1,700.20
	Switching	155		147.6		546.8		439.3
	Security	121.3		144.2		367.1		406.9
	Total product	809.5		900.8		2,614.70		2,546.40
	Total service	316.4		284.8		910.8		849.1
	Total	$	1,125.90	$	1,185.60	$	3,525.50	$	3,395.50
	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):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Americas:
	United States	$	621.3	$	604.6	$	1,905.70	$	1,761.80
	Other	57		56.7		165.1		166.7
	Total Americas	678.3		661.3		2,070.80		1,928.50
	Europe, Middle East, and Africa	290.5		306.5		911		898
	Asia Pacific	157.1		217.8		543.7		569
	Total	$	1,125.90	$	1,185.60	$	3,525.50	$	3,395.50
	No customer accounted for 10% or more of the Company's net revenues during the three and nine months ended September 30, 2014 and September 30, 2013, respectively.
	The following table presents geographic information for property and equipment, net (in millions):
		As of
		September 30,		December 31,
		2014		2013
	United States	$	806.6	$	801.3
	International	82.2		81
	Property and equipment, net	$	888.8	$	882.3
	The Company tracks assets by physical location. The majority of the Company’s assets, excluding cash and cash equivalents and investments, as of September 30, 2014 and December 31, 2013, were attributable to U.S. operations.

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes
	The Company's effective tax rate for the three and nine months ended September 30, 2014 of 37.4% and 28.4%, respectively, differs from the federal statutory rate of 35% and the effective tax rate for the same periods in 2013 primarily due to the impact of the discrete items referenced below, offset by the benefit from the Section 199 deduction for U.S. production activities and earnings in foreign jurisdictions, which are subject to lower tax rates. The effective rate for the period does not reflect the benefit of the federal R&D credit, which expired on December 31, 2013.
	The effective tax rate for the three and nine months ended September 30, 2013 of 27.9% and 15.4%, respectively, differs from the federal statutory rate of 35% primarily due to the benefit from the Section 199 deduction for U.S. production activities, earnings in foreign jurisdiction, which are subject to lower tax rates, the impact of the recognition of tax benefits related to a tax settlement with the Internal Revenue Service (“IRS”) and the reinstatement of the U.S. federal research and development (“R&D”) tax credit on January 2, 2013.
	The effective tax rates for the three and nine months ended September 30, 2014 and September 30, 2013 include the tax expense (benefit) of the following discrete items (in millions):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014		2013			2014			2013
	Tax on equity investments(1)	$	0.7	$	3		$	36.3		$	3.4
	Restructuring	$	9.2	$	(4.4	)	$	(46.7	)	$	(7.9	)
	Legal settlement	$	—	$	—		$	44.7		$	(3.8	)
	Section 199 deduction	$	—	$	0.6		$	—		$	(19.7	)
	Tax settlement with Internal Revenue Service	$	—	$	—		$	—		$	(27.8	)
	("IRS")
	Reinstatement of the U.S. federal R&D tax	$	—	$	(1.0	)	$	—		$	(16.2	)
	credit
	________________________________
	(1) During the nine months ended September 30, 2014, tax on equity investments of $36.3 million is net of a valuation allowance release of $24.7 million.
	As of September 30, 2014, the total amount of gross unrecognized tax benefits was $175.6 million, of which $164.7 million, if recognized, would affect the Company's effective tax rate. The increase in the gross unrecognized tax benefit balance for the nine months ended September 30, 2014 primarily relates to the impact on foreign income of positions taken during the current year.
	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 $2.6 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.
	The Company is currently under examination by the IRS for the 2007 through 2009 tax years. The Company is also subject to separate ongoing examinations by the India tax authorities for the 2004 tax year, 2004 through 2008 tax years, and the 2008 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 September 30, 2014.
	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 our 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	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Net Income Per Share	'
	Net Income Per Share
	The Company computed basic and diluted net income per share as follows (in millions, except per share amounts):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Numerator:
	Net income	$	103.6	$	99.1	$	435.3	$	288
	Denominator:
	Weighted-average shares used to compute	448.4		501.5		468.1		503
	basic net income per share
	Dilutive effect of employee stock awards	6.4		7.1		8.9		7.7
	Weighted-average shares used to compute	454.8		508.6		477		510.7
	diluted net income per share
	Net income per share:
	Basic	$	0.23	$	0.2	$	0.93	$	0.57
	Diluted	$	0.23	$	0.19	$	0.91	$	0.56
	Anti-dilutive:
	Potential anti-dilutive shares	10.2		21.8		10.8		22.3
	Basic net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding for the period. Diluted net income per share is computed using net income available to common stockholders and the weighted-average number of common shares outstanding plus potentially dilutive common shares outstanding during the period. Dilutive potential common shares consist of common shares issuable upon exercise of stock options, issuances of ESPP, and vesting of RSUs, RSAs, and PSAs. The Company includes the common shares underlying PSAs in the calculation of diluted net income per share 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 income per share because their effect would be anti-dilutive.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies
	Commitments
	Operating Leases
	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. Future minimum payments under the non-cancelable operating leases totaled $138.5 million as of September 30, 2014. Rent expense was $10.8 million and $36.5 million for the three and nine months ended September 30, 2014, respectively, and $12.6 million and $39.9 million for the three and nine months ended September 30, 2013, respectively.
	Purchase Commitments with Contract Manufacturers and Suppliers
	In order to reduce manufacturing lead times and help 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 $485.6 million as of September 30, 2014.
	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 September 30, 2014, the Company accrued $16.3 million based on its estimate of such charges.
	Long-Term Debt and Interest Payment on Long-Term Debt
	As of September 30, 2014, the Company held long-term debt consisting of senior notes with a carrying value of $1,348.9 million. 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 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%, 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 11, Long-Term Debt and Financing, for further discussion of the Company's long-term debt.
	Other Contractual Obligations
	As of September 30, 2014, other contractual obligations primarily consisted of $45.9 million in indemnity-related and service related escrows, as required in connection with certain asset purchases and acquisitions completed by the Company between 2005 and 2014, campus build-out obligations of $4.0 million, and $27.2 million of agreements that are firm, non-cancelable and specify terms, including: fixed or minimum quantities to be purchased; fixed, minimum or variable price provisions; and the approximate timing of payment.
	Tax Liabilities
	As of September 30, 2014, the Company had $154.2 million included in long-term income taxes payable in the Condensed 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 infringe the intellectual property rights of a third-party. 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 September 30, 2014 and December 31, 2013, the Company had $28.3 million and $40.1 million, respectively, in financing arrangements, bank guarantees, and standby letters of credit related to these financial guarantees, of which $22.1 million in financing guarantees was recorded in other accrued liabilities and other long-term liabilities in the Condensed Consolidated Balance Sheets as of September 30, 2014. See Note 11, Long-Term Debt and Financing, for further discussion of the Company's third-party customer financing arrangements that contain guarantee provisions.
	Legal Proceedings
	The Company is involved in disputes, litigation, and other legal actions, including, but not limited to, the matters described below. The Company is aggressively defending its current litigation matters. 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. Unless otherwise noted below, during the period presented, we have not recorded any accrual for loss contingencies associated with such legal proceedings; determined that an unfavorable outcome is probable or reasonably possible; or determined that the amount or range of any possible loss is reasonably estimable.
	Investigations
	The U.S. Securities and Exchange Commission and the U.S. Department of Justice are conducting investigations into possible violations by the Company of the U.S. Foreign Corrupt Practices Act. The Company is cooperating with these agencies regarding these matters. The Company is unable to predict the duration, scope or outcome of these investigations.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	Sale of Junos Pulse Net Assets
	The sale of the Junos Pulse product portfolio was completed on October 1, 2014, and the Company received a total consideration of $228.1 million, of which $103.1 million was in cash, net of a $21.9 million working capital adjustment, and $125.0 million was in the form of an 18-month non-contingent interest bearing promissory note issued to the Company. The net gain from this sale will be recorded in the fourth quarter of 2014 in the Consolidated Statements of Operations.
	Capital Allocation Program
	As part of the Company's commitment to drive stockholder value, in October 2014, the Company's Board authorized a $1.3 billion increase to the Company's previously authorized capital return program of $3.0 billion. This brings the Company's total capital return commitment to shareholders, for the period from February 2014 through 2016, including dividends, to $4.1 billion. In October 2014, the Company announced its intention to repurchase an additional $1.5 billion of its common stock before the end of the second quarter of 2015, as part of its three year capital return program.
	Dividend Declaration
	On October 23, 2014, the Company announced that it had declared a cash dividend of $0.10 per share of common stock payable on December 23, 2014 to stockholders of record as of the close of business on December 2, 2014.
	Stock Repurchase Activities
	Subsequent to September 30, 2014, through the filing of this Report, the Company repurchased 8.1 million shares of its common stock, for an aggregate of $170.0 million at an average purchase price of $21.01 per share, under the 2014 Stock Repurchase Program. Repurchases of 6.7 million shares were settled prior to the filing of this Report and the remaining shares will be settled after the filing date. Following the October 2014 increase to the 2014 Stock Repurchase Program, the Company has an aggregate of $1.5 billion in authorized repurchase 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 laws and other legal requirements. This program may be discontinued at any time.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Accounting Policies [Abstract]	'
Recent accounting pronouncements	'
	Recent Accounting Pronouncements
	In August 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-15 (Subtopic 205-40) - Presentation of Financial Statements—Going Concern: Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern ("ASU 2014-15") which provides guidance about management's responsibility to evaluate whether or not there is substantial doubt about the Company's ability to continue as a going concern and to provide related footnote disclosure. ASU 2014-15 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2016. Early application is permitted. The adoption of this standard is not expected to have an 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 is not expected to 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. ASU 2014-09 is effective for annual and interim periods beginning after December 15, 2016. Early adoption is not permitted. Accordingly, the ASU will be effective for the Company beginning fiscal year 2017. The Company is currently evaluating the impact of the adoption on its Consolidated Financial Statements.
	In April 2014, the FASB issued ASU No. 2014-08, Presentation of Financial Statements (Topic 205) and Property, Plant, and Equipment (Topic 360): Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity ("ASU 2014-08") which raises the threshold for a disposal to qualify as a discontinued operation and requires new disclosures of both discontinued operations and certain other disposals that do not meet the definition of a discontinued operation. ASU 2014-08 is effective for annual periods beginning on or after December 15, 2014. Early adoption is permitted but only for disposals that have not been reported in financial statements previously issued. The Company has determined that this pronouncement would not have a material impact on the Company's financial position or results of operations.

Business_Combination_Tables

Business Combination (Tables)	9 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
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 nine months ended September 30, 2014 (in millions, except years):
		Weighted	Amount
		Average
		Estimated
		Useful
		Life
		(In Years)
	Existing technology	7	$	10.7
	Customer relationships	7	6
	Trade name	4	0.6
	Backlog	1	0.2
	Non-compete agreements	2	0.3
	Total	7	$	17.8

Assets_Held_for_Sale_Tables

Assets Held for Sale (Tables)	9 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Carrying value of assets and liabilities held for sale [Table Text Block]	'
	The following table presents the carrying value of the major components of assets and liabilities of Junos Pulse held for sale as of September 30, 2014 (in millions):
		As of
		September 30, 2014
	Assets:
	Goodwill(1)	$	159.8
	Intangible assets	6
	Other assets	1.1
	Total assets held for sale	$	166.9
	Liabilities:
	Deferred revenue	$	38.3
	Other liabilities	2.2
	Total liabilities related to assets held for sale	$	40.5
	________________________________
	(1) Allocated goodwill is subject to final valuation to be performed in the fourth quarter of 2014.

Cash_Equivalents_and_Investmen1

Cash Equivalents and Investments (Tables)	9 Months Ended
	Sep. 30, 2014
Cash Equivalents and Investments [Abstract]	'
Unrealized gains and losses and fair value of available-for-sale and trading securities	'
	The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of September 30, 2014 and December 31, 2013 (in millions):
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	As of September 30, 2014
	Fixed income securities:
	Asset-backed securities	$	310.3	$	—		$	(0.3	)	$	310
	Certificates of deposit	12.4		—			—			12.4
	Commercial paper	12.9		—			—			12.9
	Corporate debt securities	869.8		0.8			(0.8		)	869.8
	Foreign government debt securities	28.4		—			—			28.4
	Government-sponsored enterprise obligations	200.3		0.1			(0.2		)	200.2
	U.S. government securities	269.9		0.1			—			270
	Total fixed income securities	1,704.00		1			(1.3		)	1,703.70
	Money market funds	692		—			—			692
	Mutual funds	3.8		0.1			—			3.9
	Publicly-traded equity securities	2.4		—			(0.3		)	2.1
	Total available-for-sale securities	2,402.20		1.1			(1.6		)	2,401.70
	Trading securities in mutual funds(1)	16.7		—			—			16.7
	Total	$	2,418.90	$	1.1		$	(1.6	)	$	2,418.40
	Reported as:
	Cash equivalents	$	668.2	$	—		$	—		$	668.2
	Restricted investments	45.1		—			—			45.1
	Short-term investments	299.5		0.3			(0.3		)	299.5
	Long-term investments	1,406.10		0.8			(1.3		)	1,405.60
	Total	$	2,418.90	$	1.1		$	(1.6	)	$	2,418.40
	________________________________
	(1)	Balance includes the Company's non-qualified deferred compensation plan assets.
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	As of December 31, 2013
	Fixed income securities:
	Asset-backed securities	$	249.9	$	0.1		$	(0.1	)	$	249.9
	Certificates of deposit	27.6		—			—			27.6
	Commercial paper	6.9		—			—			6.9
	Corporate debt securities	813.6		2			(0.3		)	815.3
	Foreign government debt securities	10.7		—			—			10.7
	Government-sponsored enterprise obligations	306.2		0.1			(0.1		)	306.2
	U.S. government securities	303.3		0.1			(0.1		)	303.3
	Total fixed income securities	1,718.20		2.3			(0.6		)	1,719.90
	Money market funds	1,043.70		—			—			1,043.70
	Mutual funds	3.9		0.1			—			4
	Publicly-traded equity securities	12		104.5			(1.9		)	114.6
	Total available-for-sale securities	2,777.80		106.9			(2.5		)	2,882.20
	Trading securities in mutual funds(1)	15.4		—			—			15.4
	Total	$	2,793.20	$	106.9		$	(2.5	)	$	2,897.60
	Reported as:
	Cash equivalents	$	996.2	$	—		$	—		$	996.2
	Restricted investments	87.5		0.1			—			87.6
	Short-term investments	459		104.9			(2.0		)	561.9
	Long-term investments	1,250.50		1.9			(0.5		)	1,251.90
	Total	$	2,793.20	$	106.9		$	(2.5	)	$	2,897.60
	________________________________
	(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 September 30, 2014 (in millions):
		Amortized		Gross Unrealized			Gross Unrealized			Estimated Fair
		Cost		Gains			Losses			Value
	Due in less than one year	$	297.9	$	0.2		$	—		$	298.1
	Due between one and five years	1,406.10		0.8			(1.3		)	1,405.60
	Total	$	1,704.00	$	1		$	(1.3	)	$	1,703.70
Available-for-sale securities in unrealized loss position	'
	The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of September 30, 2014 and December 31, 2013 (in millions):
		Less than 12 Months					12 Months or Greater					Total
		Fair		Unrealized			Fair			Unrealized		Fair		Unrealized
		Value		Loss			Value			Loss		Value		Loss
	As of September 30, 2014
	Fixed income securities:
	Asset-backed securities	$	237.2	$	(0.3	)	$	—		$	—	$	237.2	$	(0.3	)
	Corporate debt securities	472.8		(0.8		)	—			—		472.8		(0.8		)
	Foreign government debt securities(1)	15.9		—			—			—		15.9		—
	Government-sponsored enterprise obligations	104.2		(0.2		)	—			—		104.2		(0.2		)
	U.S. government securities(1)	21.7		—			—			—		21.7		—
	Total fixed income securities	851.8		(1.3		)	—			—		851.8		(1.3		)
	Publicly-traded equity securities	2.1		(0.3		)	—			—		2.1		(0.3		)
	Total available-for-sale securities	$	853.9	$	(1.6	)	$	—		$	—	$	853.9	$	(1.6	)
	________________________________
	(1) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of September 30, 2014.
		Less than 12 Months					12 Months or Greater					Total
		Fair		Unrealized			Fair			Unrealized		Fair		Unrealized
		Value		Loss			Value			Loss		Value		Loss
	As of December 31, 2013
	Fixed income securities:
	Asset-backed securities(1)	$	153	$	(0.1	)	$	0.6		$	—	$	153.6	$	(0.1	)
	Corporate debt securities(1)	156.1		(0.3		)	9.7			—		165.8		(0.3		)
	Foreign government debt securities(2)	10		—			—			—		10		—
	Government-sponsored enterprise obligations	123.1		(0.1		)	—			—		123.1		(0.1		)
	U.S. government securities	119.7		(0.1		)	—			—		119.7		(0.1		)
	Total fixed income securities	561.9		(0.6		)	10.3			—		572.2		(0.6		)
	Publicly-traded equity securities	6.8		(1.9		)	—			—		6.8		(1.9		)
	Total available-for-sale securities	$	568.7	$	(2.5	)	$	10.3		$	—	$	579	$	(2.5	)
	________________________________
	(1)	Balances 12 months or greater include investments that were in an immaterial unrealized loss position as of December 31, 2013.
	(2)	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2013.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Assets 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 Condensed Consolidated Balance Sheets (in millions):
		Fair Value Measurements at September 30, 2014 Using:
		Quoted Prices in		Significant Other			Significant Other
		Active Markets For		Observable			Unobservable
		Identical Assets		Remaining Inputs			Remaining Inputs
		(Level 1)		(Level 2)			(Level 3)		Total
	Assets measured at fair value:
	Available-for-sale securities:
	Asset-backed securities	$	—	$	310		$	—	$	310
	Certificates of deposit	—		12.4			—		12.4
	Commercial paper	—		12.9			—		12.9
	Corporate debt securities	—		869.8			—		869.8
	Foreign government debt securities	—		28.4			—		28.4
	Government-sponsored enterprise obligations	—		200.2			—		200.2
	Money market funds(1)	692		—			—		692
	Mutual funds(2)	3.9		—			—		3.9
	Publicly-traded equity securities	2.1		—			—		2.1
	U.S. government securities	243		27			—		270
	Total available-for-sale securities	941		1,460.70			—		2,401.70
	Trading securities in mutual funds(3)	16.7		—			—		16.7
	Privately-held debt securities	—		—			42.3		42.3
	Derivative assets:
	Foreign exchange contracts	—		1.2			—		1.2
	Total assets measured at fair value	$	957.7	$	1,461.90		$	42.3	$	2,461.90
	Liabilities measured at fair value:
	Derivative liabilities:
	Foreign exchange contracts	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total liabilities measured at fair value	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total assets measured at fair value, reported as:
	Cash equivalents	$	650.8	$	17.4		$	—	$	668.2
	Restricted investments	45.1		—			—		45.1
	Short-term investments	98.4		201.1			—		299.5
	Long-term investments	163.4		1,242.20			—		1,405.60
	Prepaid expenses and other current assets	—		1.2			—		1.2
	Other long-term assets	—		—			42.3		42.3
	Total assets measured at fair value	$	957.7	$	1,461.90		$	42.3	$	2,461.90
	Total liabilities measured at fair value, reported as:
	Other accrued liabilities	$	—	$	(1.8	)	$	—	$	(1.8	)
	Total liabilities measured at fair value	$	—	$	(1.8	)	$	—	$	(1.8	)
	________________________________
	(1)	Balance includes $41.3 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 restricted investments measured at fair market value related to the Company's India Gratuity Trust.
	(3)	Balance relates to investments measured at fair value related to the Company's non-qualified deferred compensation plan assets.
		Fair Value Measurements at December 31, 2013 Using:
		Quoted Prices in		Significant Other			Significant Other
		Active Markets For		Observable			Unobservable
		Identical Assets		Remaining Inputs			Remaining Inputs
		(Level 1)		(Level 2)			(Level 3)		Total
	Assets measured at fair value:
	Available-for-sale securities:
	Asset-backed securities	$	—	$	249.9		$	—	$	249.9
	Certificates of deposit	—		27.6			—		27.6
	Commercial paper	—		6.9			—		6.9
	Corporate debt securities	—		815.3			—		815.3
	Foreign government debt securities	—		10.7			—		10.7
	Government-sponsored enterprise obligations	—		306.2			—		306.2
	Money market funds(1)	1,043.70		—			—		1,043.70
	Mutual funds(2)	4		—			—		4
	Publicly-traded equity securities	114.6		—			—		114.6
	U.S. government securities	197.2		106.1			—		303.3
	Total available-for-sale securities	1,359.50		1,522.70			—		2,882.20
	Trading securities in mutual funds(3)	15.4		—			—		15.4
	Privately-held debt securities	—		—			28.1		28.1
Derivative assets:
Foreign exchange contracts	—		3			—		3
Total assets measured at fair value	$	1,374.90	$	1,525.70		$	28.1	$	2,928.70
Liabilities measured at fair value:
Derivative liabilities:
Foreign exchange contracts	$	—	$	(0.7	)	$	—	$	(0.7	)
Total liabilities measured at fair value	$	—	$	(0.7	)	$	—	$	(0.7	)
Total assets measured at fair value, reported as:
Cash equivalents	$	965.1	$	31.1		$	—	$	996.2
Restricted investments	87.6		—			—		87.6
Short-term investments	246.5		315.4			—		561.9
Long-term investments	75.7		1,176.20			—		1,251.90
Prepaid expenses and other current assets	—		3			—		3
Other long-term assets	—		—			28.1		28.1
Total assets measured at fair value	$	1,374.90	$	1,525.70		$	28.1	$	2,928.70
Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—	$	(0.7	)	$	—	$	(0.7	)
Total liabilities measured at fair value	$	—	$	(0.7	)	$	—	$	(0.7	)
________________________________
(1)	Balance includes $83.6 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 restricted investments measured at fair market value related to the Company's India Gratuity Trust.
(3)	Balance relates to investments measured at fair value related to the Company's non-qualified deferred compensation plan assets.

Derivative_Instruments_Tables

Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]	'
Derivative instruments	'
	The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions):
		As of
		September 30,		December 31,
		2014		2013
	Cash flow hedges	$	144.4	$	137.6
	Non-designated derivatives	94.7		144.4
	Total	$	239.1	$	282

Goodwill_and_Purchased_Intangi1

Goodwill and Purchased Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill	'
	The following table presents goodwill activity during the nine months ended September 30, 2014 (in millions):
	Balance as of December 31, 2013	$	4,057.70
	Additions due to business combination	13.6
	Goodwill reclassified to assets held for sale	(159.8		)
	Tax reserve adjustment	0.2
	Balance as of September 30, 2014	$	3,911.70
Finite-lived intangible assets by major class	'
	The Company’s purchased intangible assets were as follows (in millions):
		Gross			Accumulated			Impairments and			Net
					Amortization			Other Charges (1)
	As of September 30, 2014
	Intangible assets with finite lives:
	Technologies and patents	$	592		$	(477.8	)	$	(35.7	)	$	78.5
	Customer contracts, support agreements, and	80.3			(65.8		)	(3.0		)	11.5
	related relationships
	Other	19.9			(19.1		)	—			0.8
	Total purchased intangible assets	$	692.2		$	(562.7	)	$	(38.7	)	$	90.8
	As of December 31, 2013
	Intangible assets with finite lives:
	Technologies and patents	$	581.4		$	(453.4	)	$	(30.5	)	$	97.5
	Customer contracts, support agreements, and	74.3			(62.7		)	(2.2		)	9.4
	related relationships
	Total purchased intangible assets	$	655.7		$	(516.1	)	$	(32.7	)	$	106.9
	________________________________
	(1) Balance includes $6.0 million of unamortized intangible assets related to Junos Pulse that have been reclassified to assets held for sale.
Amortization of intangible assets included in the Condensed Consolidated Statements of Operations	'
	The following table presents the amortization of intangible assets included in the Condensed Consolidated Statements of Operations (in millions):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Cost of revenues	$	7.1		$	6.5		$	23.7		$	19.3
	Operating expenses:
	Sales and marketing	1.1			0.8			3.2			2.6
	General and administrative	0.3			0.3			0.9			0.9
	Total operating expenses	1.4			1.1			4.1			3.5
	Total	$	8.5		$	7.6		$	27.8		$	22.8
Estimated future amortization expense of purchased intangible assets with finite lives	'
	As of September 30, 2014, the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions):
	Years Ending December 31,	Amount
	Remainder of 2014	$	8.5
	2015	32.1
	2016	20.8
	2017	13
	2018	6.1
	Thereafter	10.3
	Total	$	90.8

Other_Financial_Information_Ta

Other Financial Information (Tables)	9 Months Ended
	Sep. 30, 2014
Other Financial Information [Abstract]	'
Inventories	'
	Total inventories consisted of the following (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Production materials	$	35.6		$	51.3
	Finished goods	15			1.4
	Inventories	$	50.6		$	52.7
Other long-term assets	'
	Other long-term assets consisted of the following (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Privately-held investments	$	79.3		$	57.2
	Licensed software	9.4			90.4
	Federal income tax receivable	20			20
	Financed customer receivable	18.2			19.9
	Inventory	6.8			15.2
	Prepaid costs, deposits, and other	29.2			31.1
	Other long-term assets	$	162.9		$	233.8
Warranties	'
	Changes in the Company’s warranty reserve during the nine months ended September 30, 2014 were as follows (in millions):
	Balance as of December 31, 2013	$	28
	Provisions made during the period	21.9
	Actual costs incurred during the period	(21.3		)
	Warranty reclassified to liabilities held for sale	(0.5		)
	Balance as of September 30, 2014	$	28.1
Deferred revenue	'
	Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):
		As of
		September 30,			December 31,
		2014			2013
	Deferred product revenue:
	Undelivered product commitments and other product deferrals	$	166.5		$	184.9
	Distributor inventory and other sell-through items	113			118.7
	Deferred gross product revenue	279.5			303.6
	Deferred cost of product revenue	(57.0		)	(58.6		)
	Deferred product revenue, net	222.5			245
	Deferred service revenue	851.5			824.3
	Total	$	1,074.00		$	1,069.30
	Reported as:
	Current	$	728.4		$	705.8
	Long-term	345.6			363.5
	Total	$	1,074.00		$	1,069.30
Other income (expense), net	'
	Other (expense) income, net, consisted of the following (in millions):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Interest income	$	2.7		$	2.3		$	6.9		$	6.1
	Interest expense	(16.9		)	(14.2		)	(50.2		)	(43.4		)
	Net gain on legal settlement	0.8			—			196.1			—
	(Loss) gain on investments	(1.9		)	4			165.1			7.8
	Other	8.5			0.4			8.1			(0.7		)
	Other (expense) income, net	$	(6.8	)	$	(7.5	)	$	326		$	(30.2	)

Restructuring_and_Other_Charge1

Restructuring and Other Charges (Tables)	9 Months Ended
	Sep. 30, 2014
Restructuring Charges [Abstract]	'
Summary of restructuring and other charges	'
	The following table presents restructuring and other charges included in cost of revenues and restructuring and other (credit) charges in the Condensed Consolidated Statements of Operations (in millions):
		Three Months Ended September 30,						Nine Months Ended September 30,
		2014			2013			2014			2013
	Severance	$	7.1		$	3.8		$	45.6		$	9
	Facilities	(25.0		)	(0.8		)	12.8			9.5
	Contract terminations	—			1.8			2.3			2.8
	Total restructuring charges	(17.9		)	4.8			60.7			21.3
	Asset impairment and write-downs	2.9			7.3			118.7			7.3
	Total restructuring and other (credit) charges	$	(15.0	)	$	12.1		$	179.4		$	28.6
	Reported as:
	Cost of revenues	$	—		$	6.1		$	22.2		$	7.6
	Restructuring and other (credit) charges	(15.0		)	6			157.2			21
	Total	$	(15.0	)	$	12.1		$	179.4		$	28.6
Changes in restructuring liability	'
	The following table provides a summary of changes in the restructuring liability related to the Company's plans during the nine months ended September 30, 2014 (in millions):
		December 31,			Charges			Cash			Non-cash			September 30,
		2013						Payments			Settlements and			2014
											Other
	Severance	$	5.6		$	45.6		$	(40.9	)	$	(1.0	)	$	9.3
	Facilities	5.1			12.8			(17.5		)	8.9			9.3
	Contract terminations and other	7.1			2.3			(8.3		)	(0.9		)	0.2
	Total	$	17.8		$	60.7		$	(66.7	)	$	7		$	18.8

LongTerm_Debt_and_Financing_Ta

Long-Term Debt and Financing (Tables)	9 Months Ended
	Sep. 30, 2014
Debt Instruments [Abstract]	'
Long-term debt	'
	The following table summarizes the Company's long-term debt (in millions, except percentages):
		As of September 30, 2014
		Amount			Effective Interest
					Rates
	Senior notes:
	3.10% fixed-rate notes, due 2016 ("2016 Notes")	$	300		3.25	%
	4.60% fixed-rate notes, due 2021 ("2021 Notes")	300			4.69	%
	4.50% fixed-rate notes, due 2024 ("2024 Notes")	350			4.63	%
	5.95% fixed-rate notes, due 2041 ("2041 Notes")	400			6.03	%
	Total senior notes	1,350.00
	Unaccreted discount	(1.1		)
	Total	$	1,348.90

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Components of accumulated other comprehensive income, net of taxes	'
	The components of accumulated other comprehensive income, net of related taxes, during the nine months ended September 30, 2014 were as follows (in millions):
		Unrealized			Unrealized			Foreign			Total
		Gains (Losses)			Gains (Losses)			Currency
		on Available-for-			on Cash Flow			Translation
		Sale Securities(1)			Hedges(2)			Adjustments
	Balance as of December 31, 2013	$	66.2		$	2.2		$	(3.8	)	$	64.6
	Other comprehensive gain before reclassifications	44			0.4			(3.8		)	40.6
	Amount reclassified from accumulated other	(104.0		)	(4.2		)	—			(108.2		)
	comprehensive income
	Net other comprehensive loss	(60.0		)	(3.8		)	(3.8		)	(67.6		)
	Balance as of September 30, 2014	$	6.2		$	(1.6	)	$	(7.6	)	$	(3.0	)
	________________________________
	(1)	The reclassifications out of accumulated other comprehensive income during the nine months ended September 30, 2014 for realized gains on available-for-sale securities of $104.0 million are included in other (expense) income, net, in the Condensed Consolidated Statements of Operations.
	(2)	The reclassifications out of accumulated other comprehensive income during the nine months ended September 30, 2014 for realized gains on cash flow hedges are included within cost of revenues of $0.4 million, research and development of $1.3 million, sales and marketing of $1.6 million, and general and administrative of $0.9 million for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	9 Months Ended
	Sep. 30, 2014
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 nine months ended September 30, 2014 (in millions, except for per share amounts and years):
		Outstanding Options
		Number of Shares			Weighted Average				Weighted Average		Aggregate
					Exercise Price				Remaining		Intrinsic
					per Share				Contractual Term		Value
									(In Years)
	Balance as of December 31, 2013	23.1			$	25.15
	Canceled	(0.6	)		30.34
	Exercised	(5.2	)		19.95
	Expired	(5.8	)		28.68
	Balance as of September 30, 2014	11.5			$	25.46			2.1		$	25.7
	As of September 30, 2014:
	Vested and expected-to-vest options	11.4			$	25.6			2.1		$	24.3
	Exercisable options	10.5			$	26.4			1.8		$	15.7
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 nine months ended September 30, 2014 (in millions, except per share amounts and years):
		Outstanding RSUs, RSAs, and PSAs
		Number of Shares			Weighted Average				Weighted Average		Aggregate
					Grant-Date Fair				Remaining		Intrinsic
					Value per Share				Contractual Term		Value
									(In Years)
	Balance as of December 31, 2013	25.4			$	23.44
	RSUs granted (1)(4)	8.8			22.98
	RSUs assumed (2)	0.4			22.66
	RSAs assumed (2)	0.9			22.66
	PSAs granted (3)(4)	0.8			25.59
	PSAs assumed (2)	0.2			22.66
	RSUs vested	(6.0	)		23.4
	RSAs vested	(1.1	)		19.59
	PSAs vested	(1.0	)		36.77
	RSUs canceled	(2.2	)		21.81
	PSAs canceled	(2.7	)		31.29
	Balance as of September 30, 2014	23.5			22.11				1.3		$	520.8
	________________________________
	(1)	Includes service-based and market-based RSUs granted under the 2006 Plan according to its terms.
	(2)	RSUs, RSAs, and PSAs assumed in connection with the acquisition of WANDL.
	(3)	The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to these PSAs that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.4 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 0.8 million shares.
	(4)	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. On July 22, 2014, the Company declared a cash dividend of $0.10 per share of common stock, or $43.8 million in the aggregate, to stockholders of record on September 2, 2014, which was paid on September 23, 2014.
Estimates of weighted average fair value per share under employee purchase plan and stock option plan	'
	The weighted-average assumptions used and the resulting estimates of fair value for ESPP and market-based RSUs during the three and nine months ended September 30, 2014 and September 30, 2013 were as follows:
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	ESPP (1):
	Volatility	27%		35%		30%		36%
	Risk-free interest rate	0.10%		0.10%		0.10%		0.10%
	Expected life (years)	0.5		0.5		0.5		0.5
	Dividend yield	1.80%		—		1.00%		—
	Weighted-average fair value per share	$5.13		$5.47		$5.72		$5.54
	Market-based RSUs (2):
	Volatility	—		—		36%		—
	Risk-free interest rate	—		—		1.60%		—
	Dividend yield	—		—		0% - 1.5%		—
	Weighted-average fair value per share	—		—		$18.28		—
	________________________________
	(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 a Monte Carlo valuation methodology. 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 Condensed Consolidated Statements of Operations (in millions):
		Three Months Ended September 30,								Nine Months Ended September 30,
		2014				2013				2014			2013
	Cost of revenues - Product	$	1.3			$	1.4			$	3.9		$	3.5
	Cost of revenues - Service	3.6				3.4				10.7			11.5
	Research and development	37.1				36.6				100.8			93.2
	Sales and marketing	15.9				20.4				44.9			53
	General and administrative	7.4				7.5				25.1			19.5
	Total	$	65.3			$	69.3			$	185.4		$	180.7
Disclosure of share-based compensation arrangements by share-based payment award	'
	The following table summarizes share-based compensation expense by award type (in millions):
		Three Months Ended September 30,								Nine Months Ended September 30,
		2014				2013				2014			2013
	Stock options	$	3.2			$	7.7			$	12		$	24.9
	RSUs, RSAs, and PSAs	58.2				57.7				161.9			144
	ESPP	3.9				3.9				11.5			11.8
	Total	$	65.3			$	69.3			$	185.4		$	180.7
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 September 30, 2014 (in millions, except years):
		Unrecognized				Weighted Average
		Compensation Cost				Period
						(In Years)
	Stock options	$	15.9			1.5
	RSUs, RSAs, and PSAs	$	302.8			1.9

Segments_Tables

Segments (Tables)	9 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Financial information for each segment	'
	The following table presents net revenues by product and service (in millions):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Routing	$	533.2	$	609	$	1,700.80	$	1,700.20
	Switching	155		147.6		546.8		439.3
	Security	121.3		144.2		367.1		406.9
	Total product	809.5		900.8		2,614.70		2,546.40
	Total service	316.4		284.8		910.8		849.1
	Total	$	1,125.90	$	1,185.60	$	3,525.50	$	3,395.50
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):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Americas:
	United States	$	621.3	$	604.6	$	1,905.70	$	1,761.80
	Other	57		56.7		165.1		166.7
	Total Americas	678.3		661.3		2,070.80		1,928.50
	Europe, Middle East, and Africa	290.5		306.5		911		898
	Asia Pacific	157.1		217.8		543.7		569
	Total	$	1,125.90	$	1,185.60	$	3,525.50	$	3,395.50
Long-lived Assets by Geographic Areas	'
	The following table presents geographic information for property and equipment, net (in millions):
		As of
		September 30,		December 31,
		2014		2013
	United States	$	806.6	$	801.3
	International	82.2		81
	Property and equipment, net	$	888.8	$	882.3

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Schedule of effective income tax rate reconciliation	'
	The effective tax rates for the three and nine months ended September 30, 2014 and September 30, 2013 include the tax expense (benefit) of the following discrete items (in millions):
		Three Months Ended September 30,					Nine Months Ended September 30,
		2014		2013			2014			2013
	Tax on equity investments(1)	$	0.7	$	3		$	36.3		$	3.4
	Restructuring	$	9.2	$	(4.4	)	$	(46.7	)	$	(7.9	)
	Legal settlement	$	—	$	—		$	44.7		$	(3.8	)
	Section 199 deduction	$	—	$	0.6		$	—		$	(19.7	)
	Tax settlement with Internal Revenue Service	$	—	$	—		$	—		$	(27.8	)
	("IRS")
	Reinstatement of the U.S. federal R&D tax	$	—	$	(1.0	)	$	—		$	(16.2	)
	credit
	________________________________
	(1) During the nine months ended September 30, 2014, tax on equity investments of $36.3 million is net of a valuation allowance release of $24.7 million.

Net_Income_per_Share_Tables

Net Income per Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule of earnings per share, basic and diluted	'
	The Company computed basic and diluted net income per share as follows (in millions, except per share amounts):
		Three Months Ended September 30,				Nine Months Ended September 30,
		2014		2013		2014		2013
	Numerator:
	Net income	$	103.6	$	99.1	$	435.3	$	288
	Denominator:
	Weighted-average shares used to compute	448.4		501.5		468.1		503
	basic net income per share
	Dilutive effect of employee stock awards	6.4		7.1		8.9		7.7
	Weighted-average shares used to compute	454.8		508.6		477		510.7
	diluted net income per share
	Net income per share:
	Basic	$	0.23	$	0.2	$	0.93	$	0.57
	Diluted	$	0.23	$	0.19	$	0.91	$	0.56
	Anti-dilutive:
	Potential anti-dilutive shares	10.2		21.8		10.8		22.3

Business_Combination_Intangibl

Business Combination, Intangible Assets Acquired (Details) (WANDL, Inc, [Member], USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Jan. 07, 2014
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'7 years	'
Amount	$17.80	$17.80
Existing Technology [Member]	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'7 years	'
Amount	10.7	'
Customer Relationships [Member]	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'7 years	'
Amount	6	'
Trade Names [Member]	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'4 years	'
Amount	0.6	'
Order or Production Backlog [Member]	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'1 year	'
Amount	0.2	'
Noncompete Agreements [Member]	'	'
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill [Abstract]	'	'
Weighted Average Estimated Useful Life (In Years)	'2 years	'
Amount	$0.30	'

Business_Combination_Narrative

Business Combination, Narrative (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Jan. 07, 2014	Sep. 30, 2014
In Millions, unless otherwise specified			WANDL, Inc, [Member]	WANDL, Inc, [Member]
Business Acquisition [Line Items]	'	'	'	'
Percentage of voting interests acquired	'	'	100.00%	'
Consideration transferred	'	'	$28.70	'
Intangible assets acquired	'	'	17.8	17.8
Goodwill	3,911.70	4,057.70	13.6	'
Net liabilities assumed	'	'	2.7	'
Share-based awards assumed, fair value	'	'	$34.90	'

Assets_Held_for_Sale_Details

Assets Held for Sale (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014		Jul. 22, 2014	Oct. 01, 2014
In Millions, unless otherwise specified			Junos Pulse [Member]		Junos Pulse [Member]	Subsequent Event [Member]
						Junos Pulse [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'		'	'
Consideration	'	'	'		$250	$228.10
Cash Consideration	'	'	'		'	103.1
Working Capital Adjustment	'	'	'		'	21.9
Promissory Note	'	'	'		'	125
Goodwill	'	'	159.8	[1]	'	'
Intangible assets	'	'	6		'	'
Other Assets	'	'	1.1		'	'
Assets held for sale	166.9	0	166.9		'	'
Deferred Revenue	'	'	38.3		'	'
Other Liabilities	'	'	2.2		'	'
Liabilities Held for Sale	$40.50	$0	$40.50		'	'
[1]	Allocated goodwill is subject to final valuation to be performed in the fourth quarter of 2014.

Cash_Equivalents_and_Investmen2

Cash Equivalents and Investments - Available-For-Sale and Trading Securities (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	$2,402.20		$2,777.80
Available-for-sale securities, gross unrealized gains	1.1		106.9
Available-for-sale securities, gross unrealized losses	-1.6		-2.5
Available-for-sale securities, estimated fair value	2,401.70		2,882.20
Trading securities:	'		'
Trading securities, amortized cost	16.7	[1]	15.4	[1]
Trading securities, gross unrealized gains	0	[1]	0	[1]
Trading securities, gross unrealized losses	0	[1]	0	[1]
Trading securities, estimated fair value	16.7	[1]	15.4	[1]
Available-for-sale and Trading Securities [Abstract]	'		'
Total investments, amortized cost	2,418.90		2,793.20
Total investments, gross unrealized gains	1.1		106.9
Total investments, gross unrealized losses	-1.6		-2.5
Total investments, estimated fair value	2,418.40		2,897.60
Cash equivalents [Member]	'		'
Available-for-sale and Trading Securities [Abstract]	'		'
Total investments, amortized cost	668.2		996.2
Total investments, gross unrealized gains	0		0
Total investments, gross unrealized losses	0		0
Total investments, estimated fair value	668.2		996.2
Restricted investments [Member]	'		'
Available-for-sale and Trading Securities [Abstract]	'		'
Total investments, amortized cost	45.1		87.5
Total investments, gross unrealized gains	0		0.1
Total investments, gross unrealized losses	0		0
Total investments, estimated fair value	45.1		87.6
Short-term investments [Member]	'		'
Available-for-sale and Trading Securities [Abstract]	'		'
Total investments, amortized cost	299.5		459
Total investments, gross unrealized gains	0.3		104.9
Total investments, gross unrealized losses	-0.3		-2
Total investments, estimated fair value	299.5		561.9
Long-term investments [Member]	'		'
Available-for-sale and Trading Securities [Abstract]	'		'
Total investments, amortized cost	1,406.10		1,250.50
Total investments, gross unrealized gains	0.8		1.9
Total investments, gross unrealized losses	-1.3		-0.5
Total investments, estimated fair value	1,405.60		1,251.90
Debt Securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	1,704		1,718.20
Available-for-sale securities, gross unrealized gains	1		2.3
Available-for-sale securities, gross unrealized losses	-1.3		-0.6
Available-for-sale securities, estimated fair value	1,703.70		1,719.90
Asset-backed securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	310.3		249.9
Available-for-sale securities, gross unrealized gains	0		0.1
Available-for-sale securities, gross unrealized losses	-0.3		-0.1
Available-for-sale securities, estimated fair value	310		249.9
Certificates of deposit [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	12.4		27.6
Available-for-sale securities, gross unrealized gains	0		0
Available-for-sale securities, gross unrealized losses	0		0
Available-for-sale securities, estimated fair value	12.4		27.6
Commercial paper [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	12.9		6.9
Available-for-sale securities, gross unrealized gains	0		0
Available-for-sale securities, gross unrealized losses	0		0
Available-for-sale securities, estimated fair value	12.9		6.9
Corporate debt securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	869.8		813.6
Available-for-sale securities, gross unrealized gains	0.8		2
Available-for-sale securities, gross unrealized losses	-0.8		-0.3
Available-for-sale securities, estimated fair value	869.8		815.3
Foreign government debt securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	28.4		10.7
Available-for-sale securities, gross unrealized gains	0		0
Available-for-sale securities, gross unrealized losses	0		0
Available-for-sale securities, estimated fair value	28.4		10.7
Government-sponsored enterprise obligations [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	200.3		306.2
Available-for-sale securities, gross unrealized gains	0.1		0.1
Available-for-sale securities, gross unrealized losses	-0.2		-0.1
Available-for-sale securities, estimated fair value	200.2		306.2
US government securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	269.9		303.3
Available-for-sale securities, gross unrealized gains	0.1		0.1
Available-for-sale securities, gross unrealized losses	0		-0.1
Available-for-sale securities, estimated fair value	270		303.3
Money market funds [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	692		1,043.70
Available-for-sale securities, gross unrealized gains	0		0
Available-for-sale securities, gross unrealized losses	0		0
Available-for-sale securities, estimated fair value	692		1,043.70
Mutual funds [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	3.8		3.9
Available-for-sale securities, gross unrealized gains	0.1		0.1
Available-for-sale securities, gross unrealized losses	0		0
Available-for-sale securities, estimated fair value	3.9		4
Publicly-traded equity securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities, amortized cost	2.4		12
Available-for-sale securities, gross unrealized gains	0		104.5
Available-for-sale securities, gross unrealized losses	-0.3		-1.9
Available-for-sale securities, estimated fair value	$2.10		$114.60
[1]	Balance includes the Company's non-qualified deferred compensation plan assets.

Cash_Equivalents_and_Investmen3

Cash Equivalents and Investments - Maturities of Fixed Income Investments (Details) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Schedule of Fixed Income Securities Maturities [Abstract]	'
Amortized cost due within one year	$297.90
Gross unrealized gains due within one year	0.2
Gross unrealized losses due within one year	0
Estimated fair value due within one year	298.1
Amortized cost due between one and five years	1,406.10
Gross unrealized gains due between one and five years	0.8
Gross unrealized losses due between one and five year	-1.3
Estimated fair value due between one and five year	1,405.60
Total investments, amortized cost	1,704
Gross Unrealized Gains	1
Gross Unrealized Losses	-1.3
Total investments, estimated fair value	$1,703.70

Cash_Equivalents_and_Investmen4

Cash Equivalents and Investments - Unrealized Loss on Available-for-Sale Securities (Details) (USD $)	9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	$853.90		$568.70
Unrealized loss, less than 12 months	-1.6		-2.5
Fair value, 12 months or greater	0		10.3
Unrealized loss, 12 months or greater	0		0
Total fair value, available-for-sale investments in continuous unrealized loss position	853.9		579
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-1.6		-2.5
Debt Securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	851.8		561.9
Unrealized loss, less than 12 months	-1.3		-0.6
Fair value, 12 months or greater	0		10.3
Unrealized loss, 12 months or greater	0		0
Total fair value, available-for-sale investments in continuous unrealized loss position	851.8		572.2
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-1.3		-0.6
Asset-backed securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	237.2		153	[1]
Unrealized loss, less than 12 months	-0.3		-0.1	[1]
Fair value, 12 months or greater	0		0.6	[1]
Unrealized loss, 12 months or greater	0		0	[1]
Total fair value, available-for-sale investments in continuous unrealized loss position	237.2		153.6	[1]
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.3		-0.1	[1]
Corporate debt securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	472.8		156.1	[1]
Unrealized loss, less than 12 months	-0.8		-0.3	[1]
Fair value, 12 months or greater	0		9.7	[1]
Unrealized loss, 12 months or greater	0		0	[1]
Total fair value, available-for-sale investments in continuous unrealized loss position	472.8		165.8	[1]
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.8		-0.3	[1]
Foreign government debt securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	15.9	[2]	10	[3]
Unrealized loss, less than 12 months	0	[2]	0	[3]
Fair value, 12 months or greater	0	[2]	0	[3]
Unrealized loss, 12 months or greater	0	[2]	0	[3]
Total fair value, available-for-sale investments in continuous unrealized loss position	15.9	[2]	10	[3]
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	0	[2]	0	[3]
Government-sponsored enterprise obligations [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	104.2		123.1
Unrealized loss, less than 12 months	-0.2		-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	104.2		123.1
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.2		-0.1
US government securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	21.7	[2]	119.7
Unrealized loss, less than 12 months	0	[2]	-0.1
Fair value, 12 months or greater	0	[2]	0
Unrealized loss, 12 months or greater	0	[2]	0
Total fair value, available-for-sale investments in continuous unrealized loss position	21.7	[2]	119.7
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	0	[2]	-0.1
Publicly-traded equity securities [Member]	'		'
Schedule of Available-for-sale Securities [Line Items]	'		'
Fair value, less than 12 months	2.1		6.8
Unrealized loss, less than 12 months	-0.3		-1.9
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		6.8
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	($0.30)		($1.90)
[1]	Balances 12 months or greater include investments that were in an immaterial unrealized loss position as of DecemberB 31, 2013.
[2]	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of SeptemberB 30, 2014.
[3]	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of DecemberB 31, 2013.

Cash_Equivalents_and_Investmen5

Cash Equivalents, and Investments, Narrative (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
	Investment		Investment		Investment
Cash Equivalents and Investments [Abstract]	'	'	'	'	'
Total investments in unrealized loss position	325	'	325	'	178
Other-than-temporary impairment losses, available-for-sale securities	$1.10	$0	$2.70	$0	'
Available-for-sale securities, gross realized gains	0	0	166.3	0	'
Privately-held investments	42.3	'	42.3	'	57.2
Unrealized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments	0	0	10	0	'
Cost-method Investments, Other than Temporary Impairment	1.1	2.1	1.1	2.5	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Privately-held investments	79.3	'	79.3	'	57.2
Fair Value, Measurements, Recurring [Member] | Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]	'	'	'	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'
Cost Method Investments, Fair Value Disclosure	$42.30	'	$42.30	'	$28.10

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Available-for-sale securities:	'		'
Available-for-sale securities	$2,401.70		$2,882.20
Trading securities:	'		'
Trading securities	16.7	[1]	15.4	[1]
Fair Value Measurements (Textuals)	'		'
Restricted investments	41.3		83.6
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Total assets measured at fair value	957.7		1,374.90
Liabilities measured at fair value:	'		'
Other accrued liabilities	0		0
Total liabilities measured at fair value	0		0
Cash equivalents	650.8		965.1
Restricted investments	45.1		87.6
Short-term investments	98.4		246.5
Long-term investments	163.4		75.7
Prepaid expenses and other current assets	0		0
Other long-term assets	0		0
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Total assets measured at fair value	1,461.90		1,525.70
Liabilities measured at fair value:	'		'
Other accrued liabilities	-1.8		-0.7
Total liabilities measured at fair value	-1.8		-0.7
Cash equivalents	17.4		31.1
Restricted investments	0		0
Short-term investments	201.1		315.4
Long-term investments	1,242.20		1,176.20
Prepaid expenses and other current assets	1.2		3
Other long-term assets	0		0
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Total assets measured at fair value	42.3		28.1
Liabilities measured at fair value:	'		'
Other accrued liabilities	0		0
Total liabilities measured at fair value	0		0
Cash equivalents	0		0
Restricted investments	0		0
Short-term investments	0		0
Long-term investments	0		0
Prepaid expenses and other current assets	0		0
Other long-term assets	42.3		28.1
Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Total assets measured at fair value	2,461.90		2,928.70
Liabilities measured at fair value:	'		'
Other accrued liabilities	-1.8		-0.7
Total liabilities measured at fair value	-1.8		-0.7
Cash equivalents	668.2		996.2
Restricted investments	45.1		87.6
Short-term investments	299.5		561.9
Long-term investments	1,405.60		1,251.90
Prepaid expenses and other current assets	1.2		3
Other long-term assets	42.3		28.1
Foreign exchange contract [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Derivative assets	0		0
Liabilities measured at fair value:	'		'
Derivative liabilities	0		0
Foreign exchange contract [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Derivative assets	1.2		3
Liabilities measured at fair value:	'		'
Derivative liabilities	-1.8		-0.7
Foreign exchange contract [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Derivative assets	0		0
Liabilities measured at fair value:	'		'
Derivative liabilities	0		0
Foreign exchange contract [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Derivative assets:	'		'
Derivative assets	1.2		3
Liabilities measured at fair value:	'		'
Derivative liabilities	-1.8		-0.7
Asset-backed Securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	310		249.9
Asset-backed Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	310		249.9
Asset-backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Asset-backed Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	310		249.9
Certificates of deposit [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.4		27.6
Certificates of deposit [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Certificates of deposit [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.4		27.6
Certificates of deposit [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Certificates of deposit [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.4		27.6
Commercial paper [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.9		6.9
Commercial paper [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Commercial paper [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.9		6.9
Commercial paper [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Commercial paper [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	12.9		6.9
Corporate debt securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	869.8		815.3
Corporate debt securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Corporate debt securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	869.8		815.3
Corporate debt securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Corporate debt securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	869.8		815.3
Foreign government debt securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	28.4		10.7
Foreign government debt securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Foreign government debt securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	28.4		10.7
Foreign government debt securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Foreign government debt securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	28.4		10.7
Government-sponsored enterprise obligations [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	200.2		306.2
Government-sponsored enterprise obligations [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Government-sponsored enterprise obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	200.2		306.2
Government-sponsored enterprise obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Government-sponsored enterprise obligations [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	200.2		306.2
Money market funds [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	692		1,043.70
Money market funds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	692	[2]	1,043.70	[3]
Money market funds [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0	[2]	0	[3]
Money market funds [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0	[2]	0	[3]
Money market funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	692	[2]	1,043.70	[3]
Mutual funds [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	3.9		4
Mutual funds [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	3.9	[4]	4	[4]
Trading securities:	'		'
Trading securities	16.7	[5]	15.4	[5]
Mutual funds [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0	[4]	0	[4]
Trading securities:	'		'
Trading securities	0	[5]	0	[5]
Mutual funds [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0	[4]	0	[4]
Trading securities:	'		'
Trading securities	0	[5]	0	[5]
Mutual funds [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	3.9	[4]	4	[4]
Trading securities:	'		'
Trading securities	16.7	[5]	15.4	[5]
Publicly-traded equity securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	2.1		114.6
Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	2.1		114.6
Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Publicly-traded equity securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Publicly-traded equity securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	2.1		114.6
US government securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	270		303.3
US government securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	243		197.2
US government securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	27		106.1
US government securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
US government securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	270		303.3
Available-for-sale securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	941		1,359.50
Available-for-sale securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	1,460.70		1,522.70
Available-for-sale securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	0		0
Available-for-sale securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	2,401.70		2,882.20
Debt Securities [Member]	'		'
Available-for-sale securities:	'		'
Available-for-sale securities	1,703.70		1,719.90
Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Trading securities:	'		'
Privately-held securities	0		0
Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Trading securities:	'		'
Privately-held securities	0		0
Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Trading securities:	'		'
Privately-held securities	42.3		28.1
Debt Securities [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Measurements, Recurring [Member]	'		'
Trading securities:	'		'
Privately-held securities	$42.30		$28.10
[1]	Balance includes the Company's non-qualified deferred compensation plan assets.
[2]	Balance includes $41.3 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisitions related escrows.
[3]	Balance includes $83.6 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisitions related escrows.
[4]	Balance relates to restricted investments measured at fair market value related to the Company's India Gratuity Trust.
[5]	Balance relates to investments measured at fair value related to the Company's non-qualified deferred compensation plan assets.

Fair_Value_Measurements_Narrat

Fair Value Measurements - Narrative (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
	Fair Value, Inputs, Level 2 [Member]	Fair Value, Inputs, Level 2 [Member]	Debt Securities [Member]	Debt Securities [Member]	Cost Method Investment, Privately Held Companies [Member]	Cost Method Investment, Privately Held Companies [Member]
			Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]	Fair Value, Inputs, Level 3 [Member]
			Fair Value, Measurements, Recurring [Member]	Fair Value, Measurements, Recurring [Member]	Fair Value, Measurements, Nonrecurring [Member]	Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'	'	'	'	'
Purchases of Privately-Held Investments	'	'	$200,000	$4,600,000	'	'
Cost method measured at fair value	'	'	'	'	0	2,000,000
Long-term debt, fair value	$1,432,700,000	$1,023,500,000	'	'	'	'

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]	'	'
Notional amount of foreign currency derivatives	$239.10	$282
Cash flow hedges [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Notional amount of foreign currency derivatives	144.4	137.6
Non-designated derivatives [Member]	'	'
Derivatives, Fair Value [Line Items]	'	'
Notional amount of foreign currency derivatives	$94.70	$144.40

Derivative_Instruments_Cash_Fl

Derivative Instruments, Cash Flow Hedges and Offsetting of Derivatives (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivatives, Fair Value [Line Items]	'	'	'	'
Maximum length of time hedged in cash flow hedge	'	'	'1 year	'
Foreign exchange contract [Member] | Cash flow hedging [Member]	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Derivative instruments, gain (loss) recognized in other comprehensive income (loss), Effective portion	($2.80)	($0.40)	$1.70	($4.20)
Operating expense [Member] | Foreign exchange contract [Member] | Cash flow hedging [Member]	'	'	'	'
Derivatives, Fair Value [Line Items]	'	'	'	'
Derivative instruments, gain (loss) reclassified from accumulated OCI into operating expense, Effective portion	$1.50	($1.40)	$5	$0.60

Derivative_Instruments_NonDesi

Derivative Instruments, Non-Designated Hedges (Details) (Foreign exchange contract [Member], USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Maturity period of non designated hedges derivatives	'	'	'2 months	'
Other income (expense), net [Member]	'	'	'	'
Derivative Instruments, Gain (Loss) [Line Items]	'	'	'	'
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($0.30)	($0.90)	($3.30)	($1)

Goodwill_and_Purchased_Intangi2

Goodwill and Purchased Intangible Assets, Goodwill (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Goodwill [Roll Forward]	'
Balance as of December 31, 2013	$4,057.70
Additions due to business combination	13.6
Goodwill reclassified to Assets held for sale	-159.8
Tax reserve adjustment	0.2
Balance as of September 30, 2014	$3,911.70

Goodwill_and_Purchased_Intangi3

Goodwill and Purchased Intangible Assets, Purchased Intangible Assets (Details) (USD $)	Sep. 30, 2014		Dec. 31, 2013
In Millions, unless otherwise specified
Purchased Intangible Assets [Line Items]	'		'
Finite-lived intangible assets, net	$90.80		'
Total purchased intangible assets, gross	692.2		655.7
Total purchased intangible assets, accumulated amortization	-562.7		-516.1
Total purchased intangible assets, impairments and other charges	-38.7	[1]	-32.7
Total purchased intangible assets, net	90.8		106.9
Technologies and patents [Member]	'		'
Purchased Intangible Assets [Line Items]	'		'
Finite-lived intangible assets, gross	592		581.4
Finite-lived intangible assets, accumulated amortization	-477.8		-453.4
Finite-lived intangible assets, impairments and other charges	-35.7	[1]	-30.5
Finite-lived intangible assets, net	78.5		97.5
Customer contracts, support agreements, and related relationships [Member]	'		'
Purchased Intangible Assets [Line Items]	'		'
Finite-lived intangible assets, gross	80.3		74.3
Finite-lived intangible assets, accumulated amortization	-65.8		-62.7
Finite-lived intangible assets, impairments and other charges	-3	[1]	-2.2
Finite-lived intangible assets, net	11.5		9.4
Other intangible assets [Member]	'		'
Purchased Intangible Assets [Line Items]	'		'
Finite-lived intangible assets, gross	19.9		'
Finite-lived intangible assets, accumulated amortization	-19.1		'
Finite-lived intangible assets, impairments and other charges	0	[1]	'
Finite-lived intangible assets, net	$0.80		'
[1]	Balance includes $6.0 million of unamortized intangible assets related to Junos Pulse that have been reclassified to assets held for sale.

Goodwill_and_Purchased_Intangi4

Goodwill and Purchased Intangible Assets, Finite Lived Intangible Assets by Class (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Acquired Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization of intangible assets	$8.50	$7.60	$27.80	$22.80
Cost of Revenues [Member]	'	'	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization of intangible assets	7.1	6.5	23.7	19.3
Sales and Marketing Expense [Member]	'	'	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization of intangible assets	1.1	0.8	3.2	2.6
General and Administrative Expense [Member]	'	'	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization of intangible assets	0.3	0.3	0.9	0.9
Operating expense [Member]	'	'	'	'
Acquired Finite-Lived Intangible Assets [Line Items]	'	'	'	'
Amortization of intangible assets	$1.40	$1.10	$4.10	$3.50

Goodwill_and_Purchased_Intangi5

Goodwill and Purchased Intangible Assets, Estimated Future Amortization Expense Intangible Assets (Details) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'
Remainder of 2014	$8.50
2015	32.1
2016	20.8
2017	13
2018	6.1
Thereafter	10.3
Finite-lived intangible assets, net	$90.80

Other_Financial_Information_In

Other Financial Information, Inventories, Net (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Inventory, Net [Abstract]	'	'
Production materials	$35.60	$51.30
Finished goods	15	1.4
Inventories	50.6	52.7
Restructuring charges	60.7	'
Inventory Write-down [Member] | Restructuring Plan 2014 [Member]	'	'
Inventory, Net [Abstract]	'	'
Restructuring charges	$15.50	'

Other_Financial_Information_Ot

Other Financial Information, Other Long Term Assets (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Other Long-term Assets [Abstract]	'	'
Privately-held investments	$79.30	$57.20
Licensed software	9.4	90.4
Federal income tax receivable	20	20
Financed customer receivable	18.2	19.9
Inventory	6.8	15.2
Prepaid costs, deposits, and other	29.2	31.1
Other long-term assets	162.9	233.8
Restructuring charges	60.7	'
Impairment charges related to licensed software [Member] | Restructuring Plan 2014 [Member]	'	'
Other Long-term Assets [Abstract]	'	'
Restructuring charges	$84.70	'

Other_Financial_Information_Wa

Other Financial Information, Warranties (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]	'
Balance as of December 31, 2013	$28
Provisions made during the period	21.9
Actual costs incurred during the period	-21.3
Balance as of September 30, 2014	28.1
warranty reclassified to liabilities held for sale	($0.50)

Other_Financial_Information_De

Other Financial Information, Deferred Revenue (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Deferred revenue:	'	'
Total deferred revenue	$1,074	$1,069.30
Reported as:	'	'
Current	728.4	705.8
Long-term	345.6	363.5
Total deferred revenue	1,074	1,069.30
Sales Revenue, Product, Net [Member]	'	'
Deferred revenue:	'	'
Undelivered product commitments and other product deferrals	166.5	184.9
Distributor inventory and other sell-through items	113	118.7
Deferred gross product revenue	279.5	303.6
Deferred cost of product revenue	-57	-58.6
Total deferred revenue	222.5	245
Reported as:	'	'
Total deferred revenue	222.5	245
Sales Revenue, Service, Net [Member]	'	'
Deferred revenue:	'	'
Total deferred revenue	851.5	824.3
Reported as:	'	'
Total deferred revenue	$851.50	$824.30

Other_Financial_Information_Ot1

Other Financial Information, Other Income (Expense), Net (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest income	$2.70	$2.30	$6.90	$6.10
Interest expense	-16.9	-14.2	-50.2	-43.4
Net gain on legal settlement	0.8	0	196.1	0
(Loss) gain on investments	-1.9	4	165.1	7.8
Other	8.5	0.4	8.1	-0.7
Other (expense) income, net	-6.8	-7.5	326	-30.2
Publicly-traded equity and privately-held investments, net realized gain	'	'	163	'
Privately-held investments, net gain	'	3.6	'	4.9
Palo Alto Networks [Member]	'	'	'	'
One time cash payment from PAN	$75	'	'	'

Restructuring_and_Other_Charge2

Restructuring and Other Charges (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
	sqft		right
	right
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	($15)	$12.10	$179.40	$28.60
Restructuring Reserve [Roll Forward]	'	'	'	'
31-Dec-13	'	'	17.8	'
Restructuring charges	'	'	60.7	'
Cash Payments	'	'	-66.7	'
Non-cash Settlements and Other	'	'	7	'
30-Sep-14	18.8	'	18.8	'
Area subject to Restructuring Activities	400,000	'	'	'
Area subject to Sublease	100,000	'	'	'
Duration of sublease	'2 years	'	'	'
Renewal Rights	1	'	1	'
Duration of renewal period	'6 months	'	'	'
Cost of Revenues [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	0	6.1	22.2	7.6
Operating expense [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	-15	6	157.2	21
Severance [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	7.1	3.8	45.6	9
Restructuring Reserve [Roll Forward]	'	'	'	'
31-Dec-13	'	'	5.6	'
Restructuring charges	'	'	45.6	'
Cash Payments	'	'	-40.9	'
Non-cash Settlements and Other	'	'	-1	'
30-Sep-14	9.3	'	9.3	'
Facilities [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	-25	-0.8	12.8	9.5
Restructuring Reserve [Roll Forward]	'	'	'	'
31-Dec-13	'	'	5.1	'
Restructuring charges	'	'	12.8	'
Cash Payments	'	'	-17.5	'
Non-cash Settlements and Other	'	'	8.9	'
30-Sep-14	9.3	'	9.3	'
Contract terminations [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	0	1.8	2.3	2.8
Restructuring Reserve [Roll Forward]	'	'	'	'
31-Dec-13	'	'	7.1	'
Restructuring charges	'	'	2.3	'
Cash Payments	'	'	-8.3	'
Non-cash Settlements and Other	'	'	-0.9	'
30-Sep-14	0.2	'	0.2	'
Employee Severance and Contract Terminations [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
30-Sep-14	9.5	'	9.5	'
Total restructuring charges [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	-17.9	4.8	60.7	21.3
Asset impairment and write-downs [Member]	'	'	'	'
Restructuring Reserve [Line Items]	'	'	'	'
Restructuring and other (credit) charges	2.9	7.3	118.7	7.3
Restructuring Plan 2014 [Member] | Severance [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	7.1	'	45	'
Restructuring Plan 2014 [Member] | Facilities [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	-25	'	12.6	'
Amount paid to Landlord	12.3	'	'	'
Transaction Fees	5.3	'	'	'
Restructuring Plan 2014 [Member] | Contract terminations [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	'	'	2.3	'
Restructuring Plan 2014 [Member] | Asset Write-Down [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	2.9	'	11.8	'
Restructuring Plan 2014 [Member] | Impairment charges related to licensed software [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	'	'	84.7	'
Restructuring Plan 2014 [Member] | Inventory Write-down [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	'	'	15.5	'
Restructuring Plan 2014 [Member] | Acceleration of Certain End of Life Products [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Restructuring charges	'	'	6.7	'
Minimum [Member] | Restructuring Plan 2014 [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	7	'	7	'
Minimum [Member] | Restructuring Plan 2014 [Member] | Severance [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	4	'	4	'
Minimum [Member] | Restructuring Plan 2014 [Member] | Facilities [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	2	'	2	'
Maximum [Member] | Restructuring Plan 2014 [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	9	'	9	'
Maximum [Member] | Restructuring Plan 2014 [Member] | Severance [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	5	'	5	'
Maximum [Member] | Restructuring Plan 2014 [Member] | Facilities [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	3	'	3	'
Maximum [Member] | Restructuring Plan 2014 [Member] | Contract terminations [Member]	'	'	'	'
Restructuring Reserve [Roll Forward]	'	'	'	'
Aggregate future restructuring charges expected	$1	'	$1	'

LongTerm_Debt_and_Financing_De

Long-Term Debt and Financing (Details) (USD $)

3 Months Ended

9 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Feb. 28, 2014

Sep. 30, 2014

Financing guarantee with recourse [Member]

Minimum [Member]

Maximum [Member]

Fixed rate note due 2016 [Member]

Fixed rate note due 2021 [Member]

Fixed Rate Note Due 2024 [Member]

Fixed Rate Note Due 2024 [Member]

Fixed rate note due 2041 [Member]

Long-Term Debt [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term debt, gross

$1,350

'

$1,350

'

'

'

'

'

$300

$300

$350

$350

$400

Unaccreted discount

-1.1

'

-1.1

'

'

'

'

'

'

'

'

'

'

Long-term debt

1,348.90

'

1,348.90

'

999.3

'

'

'

'

'

'

'

'

Long-term debt, effective interest rate

'

'

'

'

'

'

'

'

3.25%

4.69%

4.63%

'

6.03%

Long-term debt, stated interest rate

'

'

'

'

'

'

'

'

3.10%

4.60%

4.50%

4.50%

5.95%

Repurchase Price Percentage Related to Change of Control

101.00%

'

101.00%

'

'

'

'

'

'

'

'

'

'

Financing Arrangements [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of days due from receivable

'

'

'

'

'

'

'30 days

'90 days

'

'

'

'

'

Sale of receivable

92.8

241.4

429.2

607.1

'

'

'

'

'

'

'

'

'

Proceeds from sale and collection of receivables

128.9

210.8

473.3

579.2

'

'

'

'

'

'

'

'

'

Receivables from sale of receivables

146.2

'

146.2

'

189.8

'

'

'

'

'

'

'

'

Maximum term for guarantees related to third-party financing arrangements

'

'

'

'

'

'

'

'4 years

'

'

'

'

'

Guarantor obligations, current carrying value

'

'

'

'

'

22.1

'

'

'

'

'

'

'

Cash received from financing provider that has not been recognized as revenue

$59.50

'

$59.50

'

$62.30

'

'

'

'

'

'

'

'

LongTerm_Debt_and_Financing_Re

Long-Term Debt and Financing Revolving Credit Facility (Details) (Revolving Credit Facility [Member], USD $)	0 Months Ended
	Jun. 27, 2014
Line of Credit Facility [Line Items]	'
Line of Credit Facility, Current Borrowing Capacity	500,000,000
Line of Credit Facility, Additional Borrowing Capacity	200,000,000
Base Rate [Member] | Minimum [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	0.00%
Base Rate [Member] | Maximum [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	0.50%
Eurodollar [Member] | Minimum [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	0.90%
Eurodollar [Member] | Maximum [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	1.50%
Federal Funds Rate [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	0.50%
ICE Benchmark Administration Settlement Rate [Member]	'
Line of Credit Facility [Line Items]	'
Debt Instrument, Basis Spread on Variable Rate	1.00%

Equity_Cash_Dividends_on_Share

Equity, Cash Dividends on Shares of Common Stock (Details) (USD $)	0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 23, 2014
Stockholders' Equity Note [Abstract]	'
Common Stock, Dividends, Per Share, Cash Paid	$0.10
Dividends, Common Stock, Cash	$43.80

Equity_Stock_Repurchase_Activi

Equity, Stock Repurchase Activities (Details) (USD $)

1 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Feb. 28, 2014

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2013

Sep. 30, 2013

Jul. 23, 2014

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2014

Feb. 28, 2014

Jul. 31, 2013

Oct. 23, 2014

Oct. 31, 2014

Nov. 06, 2014

Oct. 23, 2014

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2013 Stock Repurchase Program [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

institution

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

agreement

Accelerated Share Repurchases [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock repurchase program, authorized amount

$2,100,000,000

'

'

'

'

'

'

'

'

$1,200,000,000

$1,000,000,000

'

'

'

'

Number of accelerated share repurchase agreements entered into during period

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

Number of financial institutions participating in accelerated share repurchase program

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

Accelerated share repurchases, aggregate payments made during period

'

'

'

'

'

'

'

1,200,000,000

'

'

'

'

'

'

'

Stock Repurchased and Retired During Period, Shares

'

23.5

'

4.4

17

'

'

33.3

'

'

'

'

'

6.7

'

Common stock repurchased and retired under stock repurchase program, value

'

550,000,000

900,000,000

92,900,000

328,400,000

'

'

'

'

'

'

'

'

'

'

Accelerated share repurchases, remaining amount recorded in equity

'

'

'

'

'

'

300,000,000

'

'

'

'

'

'

'

'

Stock Repurchased under ASR, Shares

'

'

'

'

'

16

'

'

'

'

'

'

'

'

'

Total Stock Repurchased under ASR

'

'

'

'

'

49.3

'

'

'

'

'

'

'

'

'

Common Stock Repurchased Under ASR Average Purchase Price

'

'

'

'

'

$24.35

'

'

'

'

'

'

'

'

'

Stock Repurchased under ASR, Shares To Be Retired

'

'

'

'

'

'

16

'

'

'

'

'

'

'

'

Common stock repurchased under stock repurchase program average purchase price (in dollars per share)

'

$23.44

'

$20.92

$19.32

'

'

'

'

'

'

'

'

$21.01

'

Stock Repurchase Program, Remaining Authorized Repurchase Amount

'

'

'

'

'

'

350,000,000

'

350,000,000

'

'

'

'

1,500,000,000

'

Additional amount authorized under Stock Repurchase Plan

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1,300,000,000

Expected Return to Shareholders, Amount

3,000,000,000

'

'

'

'

'

'

'

'

'

'

'

4,100,000,000

'

'

Intent, Stock Repurchases

'

'

'

'

'

'

'

'

'

'

'

$1,500,000,000

'

'

'

Equity_Components_of_Accumulat

Equity, Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) (USD $)	3 Months Ended			9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 2013
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]	'		'	'		'
Balance as of December 31, 2013	'		'	$64.60		'
Other comprehensive gain before reclassifications	'		'	40.6		'
Amount reclassified from accumulated other comprehensive income	'		'	-108.2		'
Other comprehensive (loss) income, net of tax	-16.1		70.3	-67.6		61.9
Balance as of September 30, 2014	-3		'	-3		'
Cost of revenues	411.1		439.1	1,342.40		1,257.70
Research and development	253.2		264.6	772.7		784.5
Sales and marketing	249.2		269.5	780.6		792.7
General and administrative	55		61.4	190.5		169.1
Unrealized Gains (Losses) on Available-for- Sale Securities	'		'	'		'
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]	'		'	'		'
Balance as of December 31, 2013	'		'	66.2	[1]	'
Other comprehensive gain before reclassifications	'		'	44	[1]	'
Amount reclassified from accumulated other comprehensive income	'		'	-104	[1]	'
Other comprehensive (loss) income, net of tax	'		'	-60	[1]	'
Balance as of September 30, 2014	6.2	[1]	'	6.2	[1]	'
Unrealized Gains (Losses) on Cash Flow Hedges	'		'	'		'
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]	'		'	'		'
Balance as of December 31, 2013	'		'	2.2	[2]	'
Other comprehensive gain before reclassifications	'		'	0.4	[2]	'
Amount reclassified from accumulated other comprehensive income	'		'	-4.2	[2]	'
Other comprehensive (loss) income, net of tax	'		'	-3.8	[2]	'
Balance as of September 30, 2014	-1.6	[2]	'	-1.6	[2]	'
Cost of revenues	'		'	0.4		'
Research and development	'		'	1.3		'
Sales and marketing	'		'	1.6		'
General and administrative	'		'	0.9		'
Foreign Currency Translation Adjustments	'		'	'		'
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]	'		'	'		'
Balance as of December 31, 2013	'		'	-3.8		'
Other comprehensive gain before reclassifications	'		'	-3.8		'
Amount reclassified from accumulated other comprehensive income	'		'	0		'
Other comprehensive (loss) income, net of tax	'		'	-3.8		'
Balance as of September 30, 2014	($7.60)		'	($7.60)		'
[1]	The reclassifications out of accumulated other comprehensive income during the nine months ended SeptemberB 30, 2014 for realized gains on available-for-sale securities of $104.0 million are included in other (expense) income, net, in the Condensed Consolidated Statements of Operations.
[2]	The reclassifications out of accumulated other comprehensive income during the nine months ended SeptemberB 30, 2014 for realized gains on cash flow hedges are included within cost of revenues of $0.4 million, research and development of $1.3 million, sales and marketing of $1.6 million, and general and administrative of $0.9 million for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)	0 Months Ended	3 Months Ended	9 Months Ended
	Sep. 23, 2014	Sep. 30, 2014	Sep. 30, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Common Stock, Dividends, Per Share, Cash Paid	$0.10	'	'	'
Share-Based Compensation Plans	'	'	'	'
Common stock, shares, issued	'	438,100,000	438,100,000	495,200,000
Outstanding stock options, restricted stock units, and restricted stock awards from awards assumed	'	4,700,000	4,700,000	'
Number of Shares	'	'	'	'
Balance as of December 31, 2013 (in shares)	'	'	23,100,000	'
Canceled (in shares)	'	'	-600,000	'
Exercised (in shares)	'	'	-5,200,000	'
Expired (in shares)	'	'	-5,800,000	'
Balance as of September 30, 2014 (in shares)	'	11,500,000	11,500,000	'
Weighted Average Exercise Price per Share	'	'	'	'
Balance as of December 31, 2013 (in dollars per share)	'	'	$25.15	'
Canceled (in dollars per share)	'	'	$30.34	'
Exercised (in dollars per share)	'	'	$19.95	'
Expired (in dollars per share)	'	'	$28.68	'
Balance as of September 30, 2014 (in dollars per share)	'	$25.46	$25.46	'
Weighted average remaining contractual term at September 30, 2014	'	'	'2 years 1 month 6 days	'
Aggregate intrinsic value at September 30, 2014	'	$25,700,000	$25,700,000	'
Vested or expected-to-vest options at September 30, 2014 (in shares)	'	11,400,000	11,400,000	'
Vested or expected-to-vest options, weighted average exercise price at September 30, 2014 (in dollars per share)	'	$25.60	$25.60	'
Vested and expected-to-vest options, weighted average remaining contractual term at September 30, 2014	'	'	'2 years 1 month 6 days	'
Vested or expected-to-vest options, aggregate intrinsic value at September 30, 2014	'	24,300,000	24,300,000	'
Exercisable options at September 30, 2014 (in shares)	'	10,500,000	10,500,000	'
Exercisable options, weighted average exercise price at September 30, 2014 (in dollars per share)	'	$26.40	$26.40	'
Exercisable options, weighted average remaining contractual term at September 30, 2014	'	'	'1 year 9 months 18 days	'
Exercisable options, aggregate intrinsic value at September 30, 2014	'	15,700,000	15,700,000	'
Share price (in dollars per share)	'	$22.15	$22.15	'
Pre-tax intrinsic value of options exercised	'	3,400,000	32,000,000	'
Dividends, Common Stock, Cash	43,800,000	'	'	'
Equity incentive plan 2006	'	'	'	'
Share-Based Compensation Plans	'	'	'	'
Number of shares in authorized	'	149,500,000	149,500,000	'
Number of shares available for future issuance	'	45,300,000	45,300,000	'
Plan 1996 and 2000 [Member]	'	'	'	'
Share-Based Compensation Plans	'	'	'	'
Maximum additional shares expire unexercised, under 1996 and 2000 plan	'	75,000,000	75,000,000	'
Equity Incentive Plan 1996, 2000, and 2006 [Member]	'	'	'	'
Share-Based Compensation Plans	'	'	'	'
Number of shares outstanding	'	30,300,000	30,300,000	'
Employee stock purchase plan 2008 [Member]	'	'	'	'
Share-Based Compensation Plans	'	'	'	'
Number of shares available for future issuance	'	3,300,000	3,300,000	'
Common stock, capital shares reserved for future issuance	'	19,000,000	19,000,000	'
Share-based compensation arrangement by share-based payment award, discount from market price	'	'	15.00%	'
Periodic payroll deduction - percentage of base salary	'	10.00%	10.00%	'
Maximum purchase of common stock, shares	'	'	6,000	'
Share-based compensation arrangement by share-based payment award, offering period	'	'	'12 months	'
Maximum purchase of common stock, value	'	'	$25,000	'
Share-based compensation arrangement by share-based payment award, expiration period	'	'	'1 year	'
Common stock, shares, issued	'	15,700,000	15,700,000	'

Employee_Benefit_Plans_Share_B

Employee Benefit Plans, Share Based Compensation, Equity Instruments Other Than Options (Details) (USD $)

0 Months Ended

3 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, except Share data, unless otherwise specified

Feb. 20, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Employee stock purchase plan 2008 [Member]

Employee stock purchase plan 2008 [Member]

Employee stock purchase plan 2008 [Member]

Employee stock purchase plan 2008 [Member]

Restricted stock units (RSUs)

Performance shares (PSAs)

Restricted stock awards (RSAs)

RSUs, RSAs, and PSAs [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value

'

$3.40

$32

'

'

'

'

'

'

'

'

Number of Shares

'

'

'

'

'

'

'

'

'

'

'

Balance as of December 31, 2013 (in shares)

'

'

'

'

'

'

'

'

'

'

25,400,000

Granted (in shares)

'

'

'

'

'

'

'

8,800,000

[1],[2]

800,000

[1],[3]

'

'

Assumed (in shares)

'

'

'

'

'

'

'

400,000

[4]

200,000

[4]

900,000

[4]

'

Vested (in shares)

'

'

'

'

'

'

'

-6,000,000

-1,000,000

-1,100,000

'

Canceled (in shares)

'

'

'

'

'

'

'

-2,200,000

-2,700,000

'

'

Balance as of September 30, 2014 (in shares)

'

'

'

'

'

'

'

'

'

'

23,500,000

Weighted Average Grant-Date Fair Value per Share

'

'

'

'

'

'

'

'

'

'

'

Balance as of December 31, 2013 (in dollars per share)

'

'

'

'

'

'

'

'

'

'

$23.44

Granted (in dollars per share)

'

'

'

'

'

'

'

$22.98

[1],[2]

$25.59

[1],[3]

'

'

Assumed (in dollars per share)

'

'

'

'

'

'

'

$22.66

[4]

$22.66

[4]

$22.66

[4]

'

Vested (in dollars per share)

'

'

'

'

'

'

'

$23.40

$36.77

$19.59

'

Canceled (in dollars per share)

'

'

'

'

'

'

'

$21.81

$31.29

'

'

Balance as of September 30, 2014 (in dollars per share)

'

'

'

'

'

'

'

'

'

'

$22.11

Weighted Average Remaining Contractual Term (In Years)

'

'

'

'

'

'

'

'

'

'

'1 year 3 months 18 days

Aggregate Intrinsic Value

'

'

'

'

'

'

'

'

'

'

$520.80

Aggregate number of shares subject to PSAs granted

'

'

'

'

'

'

'

'

400,000

'

'

Minimum shares to be issued on achievement of performance goals in respect of PSAs

'

'

'

'

'

'

'

'

0

'

'

Maximum shares to be issued on achievement of performance goals in respect of PSAs

'

'

'

'

'

'

'

'

800,000

'

'

Intended quarterly cash dividend based on most recent announcement (in dollars per share)

$0.10

'

'

'

'

'

'

'

'

'

'

Employee Stock Purchase Plan

'

'

'

'

'

'

'

'

'

'

'

Employee stock purchase plans offering period duration

'

'

'

'

'

'6 months

'

'

'

'

'

Stock issued during period, shares, employee stock purchase plans

'

'

'

1,400,000

1,500,000

2,900,000

3,300,000

'

'

'

'

Average price of common stock, per share

'

'

'

$20.01

$18.42

$19.30

$16.53

'

'

'

'

[1]

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. On July 22, 2014, the Company declared a cash dividend of $0.10 per share of common stock, or $43.8 million in the aggregate, to stockholders of record on September 2, 2014, which was paid on September 23, 2014.

[2]

Includes service-based and market-based RSUs granted under the 2006 Plan according to its terms.

[3]

The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to these PSAs that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.4 million shares. Depending on achievement of such performance goals, the range of shares that could be issued under these awards is 0 to 0.8 million shares.

[4]

RSUs, RSAs, and PSAs assumed in connection with the acquisition of WANDL.

Employee_Benefit_Plans_Assumpt

Employee Benefit Plans, Assumptions and Resulting Estimates of Fair Value (Details) (USD $)	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
ESPP [Member]	'		'		'		'
Estimates of Fair Value	'		'		'		'
Volatility	27.00%	[1]	35.00%	[1]	30.00%	[1]	36.00%	[1]
Risk-free interest rate	0.10%	[1]	0.10%	[1]	0.10%	[1]	0.10%	[1]
Expected life (years)	'6 months	[1]	'6 months	[1]	'6 months	[1]	'6 months	[1]
Dividend yield	1.80%	[1]	0.00%	[1]	1.00%	[1]	0.00%	[1]
Weighted-average fair value per share (in dollars per share)	$5.13	[1]	$5.47	[1]	$5.72	[1]	$5.54	[1]
Market-based RSUs [Member]	'		'		'		'
Estimates of Fair Value	'		'		'		'
Volatility	'		'		36.00%	[2]	'
Risk-free interest rate	'		'		1.60%	[2]	'
Weighted-average fair value per share (in dollars per share)	'		'		$18.28	[2]	'
Market-based RSUs [Member] | Minimum [Member]	'		'		'		'
Estimates of Fair Value	'		'		'		'
Dividend yield	'		'		0.00%	[2]	'
Market-based RSUs [Member] | Maximum [Member]	'		'		'		'
Estimates of Fair Value	'		'		'		'
Dividend yield	'		'		1.50%	[2]	'
[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 a Monte Carlo valuation methodology. 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.

Employee_Benefit_Plans_Share_B1

Employee Benefit Plans, Share Based Compensation by Cost and Expense Categories (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	$65.30	$69.30	$185.40	$180.70
Stock Options [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	3.2	7.7	12	24.9
RSUs, RSAs, and PSAs [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	58.2	57.7	161.9	144
ESPP [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	3.9	3.9	11.5	11.8
Cost of Revenues, Product [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	1.3	1.4	3.9	3.5
Cost of Revenues, Service [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	3.6	3.4	10.7	11.5
Research and Development [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	37.1	36.6	100.8	93.2
Sales and Marketing [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	15.9	20.4	44.9	53
General and Administrative [Member]	'	'	'	'
Stock Based Compensation Expense Recorded in Cost and Expense Categories	'	'	'	'
Share-based compensation expense	$7.40	$7.50	$25.10	$19.50

Employee_Benefit_Plans_Share_B2

Employee Benefit Plans, Share Based Compensation by Share Based Payment Award Types (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Stock Options [Member]	'
Unrecognized Compensation Cost [Abstract]	'
Unrecognized Compensation Cost	$15.90
Weighted Average Period (In Years)	'1 year 6 months
RSUs, RSAs, and PSAs [Member]	'
Unrecognized Compensation Cost [Abstract]	'
Unrecognized Compensation Cost	$302.80
Weighted Average Period (In Years)	'1 year 10 months 24 days

Segments_Details

Segments (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	$1,125.90	$1,185.60	$3,525.50	$3,395.50
Routing [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	533.2	609	1,700.80	1,700.20
Switching [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	155	147.6	546.8	439.3
Security [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	121.3	144.2	367.1	406.9
Total product [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	809.5	900.8	2,614.70	2,546.40
Total service [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Total net revenues	$316.40	$284.80	$910.80	$849.10

Segments_Geographical_Details

Segments, Geographical (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	$1,125.90	$1,185.60	$3,525.50	$3,395.50	'
Property and equipment, net	888.8	'	888.8	'	882.3
United States [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	621.3	604.6	1,905.70	1,761.80	'
Property and equipment, net	806.6	'	806.6	'	801.3
Other [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	57	56.7	165.1	166.7	'
Americas [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	678.3	661.3	2,070.80	1,928.50	'
EMEA [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	290.5	306.5	911	898	'
Asia Pacific [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Total net revenues	157.1	217.8	543.7	569	'
International [Member]	'	'	'	'	'
Net Revenues by Geographic Region [Line Items]	'	'	'	'	'
Property and equipment, net	$82.20	'	$82.20	'	$81

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended				9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Dec. 31, 2009	Sep. 30, 2014
									Foreign country	Maximum [Member]
Income Tax Contingency [Line Items]	'		'		'		'		'	'
Tax on equity investments(1)	$0.70	[1]	$3	[1]	$36.30	[1]	$3.40	[1]	'	'
Restructuring	9.2		-4.4		-46.7		-7.9		'	'
Legal settlement	0		0		44.7		-3.8		'	'
Section 199 Deduction	0		0.6		0		-19.7		'	'
Tax settlement with Internal Revenue Service (IRS)	0		0		0		-27.8		'	'
Reinstatement of the U.S. federal R&D tax credit	0		-1		0		-16.2		'	'
Valuation allowance release related to gain on sale of equity investments	'		'		24.7		'		'	'
Effective income tax rate reconciliation, at federal statutory income tax rate	37.40%		27.90%		28.40%		15.40%		'	'
Federal statutory rate	35.00%		35.00%		'		'		'	'
Unrecognized tax benefits	175.6		'		175.6		'		'	'
Unrecognized tax benefits that would impact effective tax rate	164.7		'		164.7		'		'	'
Greater than remote likelihood decrease in gross unrecognized tax benefits within next 12 months	'		'		'		'		'	2.6
Interest and penalties recorded	'		'		'		'		$4.60	'
[1]	During the nine months ended September 30, 2014, tax on equity investments of $36.3 million is net of a valuation allowance release of $24.7 million.

Net_Income_per_Share_Details

Net Income per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator	'	'	'	'
Net income	$103.60	$99.10	$435.30	$288
Denominator	'	'	'	'
Weighted-average shares used to compute basic net income per share	448.4	501.5	468.1	503
Dilutive effect of employee stock awards	6.4	7.1	8.9	7.7
Weighted-average shares used to compute diluted net income per share	454.8	508.6	477	510.7
Net income per share:	'	'	'	'
Basic	$0.23	$0.20	$0.93	$0.57
Diluted	$0.23	$0.19	$0.91	$0.56
Net Income per Share Textuals	'	'	'	'
Potential anti-dilutive shares	10.2	21.8	10.8	22.3

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2014	Feb. 28, 2014	Sep. 30, 2014
						Fixed rate note due 2016 [Member]	Fixed rate note due 2021 [Member]	Fixed Rate Note Due 2024 [Member]	Fixed Rate Note Due 2024 [Member]	Fixed rate note due 2041 [Member]
Summarization of principal contractual obligations	'	'	'	'	'	'	'	'	'	'
Future minimum payments under the non-cancelable operating leases	$138.50	'	$138.50	'	'	'	'	'	'	'
Rent expense	10.8	12.6	36.5	39.9	'	'	'	'	'	'
Total purchase commitments	485.6	'	485.6	'	'	'	'	'	'	'
Accrual for estimated carrying charges or obsolete materials charges	16.3	'	16.3	'	'	'	'	'	'	'
Long-term debt, carrying value	1,348.90	'	1,348.90	'	999.3	'	'	'	'	'
Long-term debt, gross	1,350	'	1,350	'	'	300	300	350	350	400
Long-term debt, stated interest rate	'	'	'	'	'	3.10%	4.60%	4.50%	4.50%	5.95%
Indemnity-related and service-related escrows	45.9	'	45.9	'	'	'	'	'	'	'
Campus build out commitments	4	'	4	'	'	'	'	'	'	'
Other contractual obligations	27.2	'	27.2	'	'	'	'	'	'	'
Long-term income taxes payable	$154.20	'	$154.20	'	$114.40	'	'	'	'	'

Commitments_and_Contingencies_1

Commitments and Contingencies, Guarantees (Details) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financing guarantees, bank guarantees, and standby letters of credit [Member]	'	'
Guarantor Obligations [Line Items]	'	'
Guarantor obligations, current carrying value	$28.30	$40.10
Financing guarantee with recourse [Member]	'	'
Guarantor Obligations [Line Items]	'	'
Guarantor obligations, current carrying value	$22.10	'

Subsequent_Events_Details

Subsequent Events (Details) (USD $)

0 Months Ended

1 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

Share data in Millions, except Per Share data, unless otherwise specified

Sep. 23, 2014

Feb. 28, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2013

Oct. 23, 2014

Oct. 31, 2014

Mar. 31, 2014

Sep. 30, 2014

Nov. 06, 2014

Oct. 23, 2014

Jul. 22, 2014

Oct. 01, 2014

Subsequent Event [Member]

Subsequent Event [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

2014 Stock Repurchase Program [Member]

Junos Pulse [Member]

Junos Pulse [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Consideration

'

'

'

'

'

'

'

'

'

'

'

$250,000,000

$228,100,000

Cash Consideration

'

'

'

'

'

'

'

'

'

'

'

'

103,100,000

Working Capital Adjustment

'

'

'

'

'

'

'

'

'

'

'

'

21,900,000

Promissory Note

'

'

'

'

'

'

'

'

'

'

'

'

125,000,000

Additional amount authorized under Stock Repurchase Plan

'

'

'

'

'

'

'

'

'

'

1,300,000,000

'

'

Expected Return to Shareholders, Amount

'

3,000,000,000

'

'

'

'

4,100,000,000

'

'

'

'

'

'

Intent, Stock Repurchases

'

'

'

'

'

1,500,000,000

'

'

'

'

'

'

'

Common Stock, Dividends, Per Share, Cash Paid

$0.10

'

'

'

'

$0.10

'

'

'

'

'

'

'

Stock Repurchased During Period, Shares

'

'

'

'

'

'

'

'

'

8.1

'

'

'

Stock Repurchased During Period, Value

'

'

'

'

'

'

'

'

'

170,000,000

'

'

'

Common Stock Repurchased Under Stock Repurchase Program Average Purchase Price

'

'

$23.44

$20.92

$19.32

'

'

'

'

$21.01

'

'

'

Stock Repurchased and Retired During Period, Shares

'

'

23.5

4.4

17

'

'

33.3

'

6.7

'

'

'

Stock Repurchase Program, Remaining Authorized Repurchase Amount

'

'

'

'

'

'

'

'

$350,000,000

$1,500,000,000

'

'

'