Juniper Networks (JNPR) 10-Q8 May 152015 Q1 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
Document and Entity Information	Mar. 31, 2015	1-May-15
Document and Entity Information [Abstract]
Entity Registrant Name	JUNIPER NETWORKS INC
Entity Central Index Key	1043604
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	-19
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		394,836,767

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (Unaudited) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net revenues:
Product	$764.10	$876
Service	303.3	294.1
Total net revenues	1,067.40	1,170.10
Cost of revenues:
Product	288.8	326.6
Service	121.3	123.4
Total cost of revenues	410.1	450
Gross margin	657.3	720.1
Operating expenses:
Research and development	248.7	264
Sales and marketing	220.2	273.4
General and administrative	55.2	74.9
Restructuring and other charges	1.4	114
Total operating expenses	525.5	726.3
Operating income (loss)	131.8	-6.2
Other (expense) income, net	-15.8	154.2
Income before income taxes	116	148
Income tax provision	35.8	37.4
Net income	$80.20	$110.60
Net income per share:
Basic, in dollars per share	$0.20	$0.23
Diluted, in dollars per share	$0.19	$0.22
Shares used in computing net income per share:
Basic (in shares)	407.1	486.2
Diluted (in shares)	414.2	496.5
Cash dividends declared per common stock (in dollar per share)	$0.10	$0

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$80.20	$110.60
Available-for-sale securities:
Unrealized (loss) gain on available-for-sale securities, net of tax provisions of ($3.8) and ($22.1), respectively	-0.8	38.1
Reclassification adjustment for realized net gains on available-for-sale securities included in net income, net of tax provision of zero and $60.3, respectively	-0.2	-103.5
Net change on available-for-sale securities, net of taxes	-1	-65.4
Cash flow hedges:
Unrealized (losses) gains on cash flow hedges, net of tax provisions of ($0.3) and ($0.6), respectively	-6.4	2.1
Reclassification adjustment for realized net losses (gains) on cash flow hedges included in net income, net of tax provision (benefit) of $0.1 and ($0.1), respectively	3.1	-1.1
Net change on cash flow hedges, net of taxes	-3.3	1
Change in foreign currency translation adjustments	-11.1	1.7
Other comprehensive loss, net of tax	-15.4	-62.7
Comprehensive income	$64.80	$47.90

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Comprehensive Income Parentheticals (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Tax provision on change in unrealized (loss) gain on available-for-sale securities	($3.80)	($22.10)
Tax provision on reclassification adjustment for realized net gains on available-for-sale securities included in net income	0	60.3
Tax provision on change in unrealized (losses) gains on cash flow hedges	-0.3	-0.6
Tax provision (benefit) on reclassification adjustment for realized losses (gains) included in net income	$0.10	($0.10)

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$1,810.80	$1,639.60
Short-term investments	398.2	332.2
Accounts receivable, net of allowances	507.6	598.9
Deferred tax assets, net	148.2	147
Prepaid expenses and other current assets	236.9	254.2
Total current assets	3,101.70	2,971.90
Property and equipment, net	912.2	904.3
Long-term investments	1,241.60	1,133.10
Restricted cash and investments	46	46
Purchased intangible assets, net	50.5	62.4
Goodwill	2,981.30	2,981.50
Other long-term assets	333.3	303.9
Total assets	8,666.60	8,403.10
Current liabilities:
Short-term debt	299.9	0
Accounts payable	223.6	234.6
Accrued compensation	169.9	225
Deferred revenue	855.5	780.8
Other accrued liabilities	221.5	287.3
Total current liabilities	1,770.40	1,527.70
Long-term debt	1,648.70	1,349
Long-term deferred revenue	319.2	294.9
Long-term income taxes payable	178.9	177.5
Other long-term liabilities	132.3	134.9
Total liabilities	4,049.50	3,484
Commitments and contingencies (Note 15)
Stockholders' equity:
Convertible preferred stock, $0.00001 par value; 10.0 shares authorized; none issued and outstanding	0	0
Common stock, $0.00001 par value; 1,000.0 shares authorized; 403.8 shares and 416.2 shares issued and outstanding as of March 31, 2015 and December 31, 2014, respectively	0	0
Additional paid-in capital	8,584.70	8,794
Accumulated other comprehensive loss	-29.2	-13.8
Accumulated deficit	-3,938.40	-3,861.10
Total stockholders' equity	4,617.10	4,919.10
Total liabilities and stockholders' equity	$8,666.60	$8,403.10

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets Parentheticals (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
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	403,800,000	416,200,000
Common stock - outstanding	403,800,000	416,200,000

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$80.20	$110.60
Adjustments to reconcile net income to net cash provided by operating activities:
Share-based compensation expense	46	60.8
Depreciation, amortization, and accretion	47.5	48.1
Restructuring and other charges	1.4	122.4
Deferred income taxes	11.3	-44.5
Gain on investments, net	-0.6	-166.2
Excess tax benefits from share-based compensation	-1.7	-6.7
Loss on disposal of fixed assets	0	0.8
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable, net	54.2	-15.7
Prepaid expenses and other assets	-21.8	-15.7
Accounts payable	-7.8	19
Accrued compensation	-54.1	-92
Income taxes payable	14.1	73.1
Other accrued liabilities	-48.4	-52.2
Deferred revenue	99	82.8
Net cash provided by operating activities	219.3	124.6
Cash flows from investing activities:
Purchases of property and equipment	-44.2	-57.4
Purchases of available-for-sale investments	-398.8	-327.1
Proceeds from sales of available-for-sale investments	169.5	1,221.40
Proceeds from maturities of available-for-sale investments	57.3	79.3
Purchases of trading investments	-1.9	-1.8
Proceeds from sales of privately-held investments	0	2.5
Purchases of privately-held investments	-3.2	-1.7
Payments for business acquisitions, net of cash and cash equivalents acquired	0	-27.1
Changes in restricted cash	0	24.9
Net cash (used in) provided by investing activities	-221.3	913
Cash flows from financing activities:
Proceeds from issuance of common stock	31.8	101.2
Purchases and retirement of common stock	-402.4	-905.8
Purchase of equity forward contract	0	-300
Issuance of long-term debt, net	594.6	346.5
Payment for capital lease obligation	0.4	-0.4
Customer financing arrangements	0	8
Excess tax benefits from share-based compensation	1.7	6.7
Payment of cash dividends	-40.8	0
Net cash provided by (used in) financing activities	185.3	-743.8
Effect of foreign currency exchange rates on cash and cash equivalents	-12.1	1.6
Net increase in cash and cash equivalents	171.2	295.4
Cash and cash equivalents at beginning of period	1,639.60	2,284
Cash and cash equivalents at end of period	$1,810.80	$2,579.40

Basis_of_Presentation

Basis of Presentation	3 Months Ended
Basis of Presentation	Mar. 31, 2015
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 March 31, 2015, is derived from the audited Consolidated Financial Statements for the year ended December 31, 2014. In the opinion of management, all adjustments, including normal recurring accruals, considered necessary for a fair presentation have been included. The results of operations for the three months ended March 31, 2015, are not necessarily indicative of the results that may be expected for the year ending December 31, 2015, 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, 2014. 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 2014, the Company realigned its organization into a One-Juniper structure which included consolidating each of the Company's research and development ("R&D) and go-to-market functions. As a result of these changes, the Company's consolidated business is considered to be one reportable segment.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2015
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, 2014.

	Recent Accounting Pronouncements

	In April 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2015-05 (Subtopic 350-40) - Customer's Accounting for Fees Paid in a Cloud Computing Arrangement, which provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 is effective for fiscal years, beginning after December 15, 2015. Early adoption is permitted. The Company is currently evaluating the impact of the adoption on its Condensed Consolidated Financial Statements, if any.

	In April 2015, the FASB issued ASU No. 2015-03 (Subtopic 835-30) - Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard would reduce the debt issuance cost asset on the Company's Condensed Consolidated Balance Sheet by approximately $11.0 million and correspondingly reduce its debt liabilities by approximately $11.0 million. The Company plans to adopt this standard in the first quarter of 2016. There would be no impact to the Condensed Consolidated Statement of Operations.

	In January 2015, the FASB issued ASU No. 2015-01 (Subtopic 225-20) - Income Statement - Extraordinary and Unusual Items, which eliminates the concept of extraordinary items. ASU 2015-01 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard will not have an impact on the Company's Condensed Consolidated Financial Statements.

	In November 2014, the FASB issued ASU No. 2014-16 (Topic 815) - Derivatives and Hedging, which provides clarification on how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features in evaluating the host contract and that no single term or feature would necessarily determine the economic characteristics and risks of the host contract. ASU 2014-16 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The amendment should be applied on a modified retrospective basis to existing hybrid financial instruments issued in the form of a share as of the beginning of the year for which the amendments are effective. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company's Condensed Consolidated Financial Statements.

	In August 2014, the FASB issued 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 Condensed 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 Condensed 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. In April 2015, the FASB proposed to defer the effective date of the new revenue standard by one year. As a result, the Company would apply the new revenue standard for annual and interim periods beginning after December 15, 2017, with early adoption permitted before annual periods beginning after December 15, 2016. 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 Condensed Consolidated Financial Statements.

Cash_Equivalents_and_Investmen

Cash Equivalents and Investments	3 Months Ended
	Mar. 31, 2015
Cash Equivalents and Investments [Abstract]
Cash Equivalents and Investments	Cash Equivalents and Investments

	Investments in Available-for-Sale and Trading Securities

	The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of March 31, 2015 and December 31, 2014 (in millions):


		Amortized			Gross Unrealized			Gross Unrealized				Estimated Fair
		Cost			Gains			Losses				Value
	As of March 31, 2015
	Fixed income securities:
	Asset-backed securities	$	308.9		$	0.1		$	(0.2	)		$	308.8

	Certificates of deposit	8.2			—			—				8.2

	Commercial paper	15.6			—			—				15.6

	Corporate debt securities	843.2			1.1			(0.5		)		843.8

	Foreign government debt securities	34.7			—			—				34.7

	Government-sponsored enterprise obligations	190.3			0.1			—				190.4

	U.S. government securities	233.7			0.2			—				233.9

	Total fixed income securities	1,634.60			1.5			(0.7		)		1,635.40

	Money market funds	776.2			—			—				776.2

	Mutual funds	4			0.1			—				4.1

	Publicly-traded equity securities	2			0.6			—				2.6

	Total available-for-sale securities	2,416.80			2.2			(0.7		)		2,418.30

	Trading securities in mutual funds(1)	17.7			—			—				17.7

	Total	$	2,434.50		$	2.2		$	(0.7	)		$	2,436.00


	Reported as:
	Cash equivalents	$	750.8		$	—		$	—			$	750.8

	Restricted investments	45.3			0.1			—				45.4

	Short-term investments	397.5			0.8			(0.1		)		398.2

	Long-term investments	1,240.90			1.3			(0.6		)		1,241.60

	Total	$	2,434.50		$	2.2		$	(0.7	)		$	2,436.00

	________________________________

	(1)	Balance consists of the Company's non-qualified deferred compensation plan assets.


		Amortized			Gross Unrealized			Gross Unrealized				Estimated Fair
		Cost			Gains			Losses				Value
	As of December 31, 2014
	Fixed income securities:
	Asset-backed securities	$	269.3		$	—		$	(0.3	)		$	269

	Certificates of deposit	10.6			—			—				10.6

Commercial paper	20.3			—			—				20.3

Corporate debt securities	738.6			0.5			(1.1		)		738

Foreign government debt securities	24.6			—			—				24.6

Government-sponsored enterprise obligations	162.2			—			(0.1		)		162.1

U.S. government securities	246.1			—			(0.1		)		246

Total fixed income securities	1,471.70			0.5			(1.6		)		1,470.60

Money market funds	594.2			—			—				594.2

Mutual funds	3.9			0.1			—				4

Publicly-traded equity securities	2.1			—			(0.1		)		2

Total available-for-sale securities	2,071.90			0.6			(1.7		)		2,070.80

Trading securities in mutual funds(1)	16.3			—			—				16.3

Total	$	2,088.20		$	0.6		$	(1.7	)		$	2,087.10


Reported as:
Cash equivalents	$	576.6		$	—		$	—			$	576.6

Restricted investments	45.2			—			—				45.2

Short-term investments	332.2			0.2			(0.2		)		332.2

Long-term investments	1,134.20			0.4			(1.5		)		1,133.10

Total	$	2,088.20		$	0.6		$	(1.7	)		$	2,087.10


________________________________

(1)	Balance consists of 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 March 31, 2015 (in millions):


	Amortized			Gross Unrealized			Gross Unrealized				Estimated Fair
	Cost			Gains			Losses				Value
Due in less than one year	$	393.7		$	0.2		$	(0.1	)		$	393.8

Due between one and five years	1,240.90			1.3			(0.6		)		1,241.60

Total	$	1,634.60		$	1.5		$	(0.7	)		$	1,635.40


The Company had 354 and 437 investments in an unrealized loss positions as of March 31, 2015 and December 31, 2014, respectively. The gross unrealized losses related to these investments were primarily due to changes in market interest rates and stock prices. The Company periodically reviews its investments to identify and evaluate investments that have an indication of possible impairment. The Company aggregates its investments by category and length of time the securities have been in a continuous unrealized loss position to facilitate its evaluation.

For available-for-sale debt securities that have unrealized losses, the Company evaluates whether (i) it has the intention to sell any of these investments and (ii) whether it is more likely than not that it will be required to sell any of these investments before recovery of the entire amortized cost basis. The Company anticipates that it will recover the entire amortized cost basis of such available-for-sale debt securities and has determined that no other-than-temporary impairments associated with credit losses were required to be recognized during the three months ended March 31, 2015 and March 31, 2014.

For available-for-sale equity securities that have unrealized losses, the Company evaluates whether there is an indication of other-than-temporary impairments. This determination is based on several factors, including the financial condition and near-term prospects of the issuer and the Company's intent and ability to hold the publicly-traded equity securities for a period of time sufficient to allow for any anticipated recovery in market value. During the three months ended March 31, 2014, the Company determined that certain available-for-sale equity securities were other-than-temporarily impaired, resulting in an impairment charge of $1.6 million, which was recorded within other (expense) income, net, in the Condensed Consolidated Statements of Operations. During the three months ended March 31, 2015 the Company did not recognize other-than-temporary impairments associated with these investments.

During the three months ended March 31, 2015, 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 months ended March 31, 2014, gross realized gains from available-for-sale securities were $165.5 million and gross realized losses were not material, excluding the impairment charge noted above. During the three months ended March 31, 2014, there were no material gross realized gains or losses from trading securities.

The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of March 31, 2015 and December 31, 2014 (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 March 31, 2015
Fixed income securities:
Asset-backed securities(1)	$	222.4		$	(0.2	)	$	1.7			$	—		$	224.1	$	(0.2	)

Corporate debt securities	391.5			(0.5		)	—				—			391.5		(0.5		)

Foreign government debt securities(2)	29.1			—			—				—			29.1		—

Government-sponsored enterprise obligations(2)	60.4			—			—				—			60.4		—

U.S. government securities(2)	47.5			—			—				—			47.5		—

Total fixed income securities	750.9			(0.7		)	1.7				—			752.6		(0.7		)

Total available-for-sale securities	$	750.9		$	(0.7	)	$	1.7			$	—		$	752.6	$	(0.7	)

________________________________
(1) Balances greater than 12 months include investments that were in an immaterial unrealized loss position as of March 31, 2015.
(2) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of March 31, 2015.



	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, 2014
Fixed income securities:
Asset-backed securities	$	221.9		$	(0.3	)	$	—			$	—		$	221.9	$	(0.3	)

Corporate debt securities	515.9			(1.1		)	—				—			515.9		(1.1		)

Foreign government debt securities(1)	24.6			—			—				—			24.6		—

Government-sponsored enterprise obligations	113.8			(0.1		)	—				—			113.8		(0.1		)

U.S. government securities	189			(0.1		)	—				—			189		(0.1		)

Total fixed income securities	1,065.20			(1.6		)	—				—			1,065.20		(1.6		)

Publicly-traded equity securities	2			(0.1		)	—				—			2		(0.1		)

Total available-for-sale securities	$	1,067.20		$	(1.7	)	$	—			$	—		$	1,067.20	$	(1.7	)

________________________________

(1)	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2014.

Restricted Cash and Investments

The Company classifies certain cash and investments as restricted cash and investments on its 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

The Company has privately-held investments, which include debt and redeemable preferred stock securities that are carried at fair value, and non-redeemable preferred stock securities that are carried at cost.

As of March 31, 2015 and December 31, 2014, the carrying values of the Company's privately-held investments of $93.1 million and $89.9 million, respectively, were included in other long-term assets in the Condensed Consolidated Balance Sheets. As of March 31, 2015 and December 31, 2014, the carrying value of the privately-held investments includes debt and redeemable preferred stock securities of $50.3 million and $47.5 million, respectively. For the three months ended March 31, 2015 and March 31, 2014, there were no unrealized gains or losses associated with the privately-held debt and redeemable preferred stock securities.

The Company reviews its investments to identify and evaluate investments that have an indication of possible impairment. During the three months ended March 31, 2015 and March 31, 2014, the Company determined that no privately-held investments were other-than-temporarily impaired.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	Assets and Liabilities Measured at Fair Value on a Recurring Basis
	The following tables provide a summary of assets and liabilities measured at fair value on a recurring basis and as reported in the Condensed Consolidated Balance Sheets (in millions):


		Fair Value Measurements at March 31, 2015 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	$	—		$	308.8			$	—		$	308.8

	Certificates of deposit	—			8.2				—			8.2

	Commercial paper	—			15.6				—			15.6

	Corporate debt securities	—			843.8				—			843.8

	Foreign government debt securities	—			34.7				—			34.7

	Government-sponsored enterprise obligations	—			190.4				—			190.4

	Money market funds(1)	776.2			—				—			776.2

	Mutual funds(2)	4.1			—				—			4.1

	Publicly-traded equity securities	2.6			—				—			2.6

	U.S. government securities	221.6			12.3				—			233.9

	Total available-for-sale securities	1,004.50			1,413.80				—			2,418.30

	Trading securities in mutual funds(3)	17.7			—				—			17.7

	Privately-held debt and redeemable preferred stock	—			—				50.3			50.3
	securities
	Derivative assets:
	Foreign exchange contracts	—			0.5				—			0.5

	Total assets measured at fair value	$	1,022.20		$	1,414.30			$	50.3		$	2,486.80

	Liabilities measured at fair value:
	Derivative liabilities:
	Foreign exchange contracts	$	—		$	(6.7	)		$	—		$	(6.7	)

	Total liabilities measured at fair value	$	—		$	(6.7	)		$	—		$	(6.7	)


	Total assets measured at fair value, reported as:
	Cash equivalents	$	735		$	15.8			$	—		$	750.8

	Restricted investments	45.4			—				—			45.4

	Short-term investments	65.2			333				—			398.2

	Long-term investments	176.6			1,065.00				—			1,241.60

	Prepaid expenses and other current assets	—			0.5				—			0.5

	Other long-term assets	—			—				50.3			50.3

	Total assets measured at fair value	$	1,022.20		$	1,414.30			$	50.3		$	2,486.80


Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—		$	(6.7	)		$	—		$	(6.7	)

Total liabilities measured at fair value	$	—		$	(6.7	)		$	—		$	(6.7	)

________________________________

(1)	Balance includes $41.2 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisition-related escrows.

(2)	Balance relates to 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, 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	$	—		$	269			$	—		$	269

Certificates of deposit	—			10.6				—			10.6

Commercial paper	—			20.3				—			20.3

Corporate debt securities	—			738				—			738

Foreign government debt securities	—			24.6				—			24.6

Government-sponsored enterprise obligations	—			162.1				—			162.1

Money market funds(1)	594.2			—				—			594.2

Mutual funds(2)	4			—				—			4

Publicly-traded equity securities	2			—				—			2

U.S. government securities	246			—				—			246

Total available-for-sale securities	846.2			1,224.60				—			2,070.80

Trading securities in mutual funds(3)	16.3			—				—			16.3

Privately-held debt and redeemable preferred stock	—			—				47.5			47.5
securities
Derivative assets:
Foreign exchange contracts	—			0.1				—			0.1

Total assets measured at fair value	$	862.5		$	1,224.70			$	47.5		$	2,134.70

Liabilities measured at fair value:
Derivative liabilities:
Foreign exchange contracts	$	—		$	(3.9	)		$	—		$	(3.9	)

Total liabilities measured at fair value	$	—		$	(3.9	)		$	—		$	(3.9	)


Total assets measured at fair value, reported as:
Cash equivalents	$	552.9		$	23.7			$	—		$	576.6

Restricted investments	45.2			—				—			45.2

Short-term investments	87			245.2				—			332.2

Long-term investments	177.4			955.7				—			1,133.10

Prepaid expenses and other current assets	—			0.1				—			0.1

Other long-term assets	—			—				47.5			47.5

Total assets measured at fair value	$	862.5		$	1,224.70			$	47.5		$	2,134.70


Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—		$	(3.9	)		$	—		$	(3.9	)

Total liabilities measured at fair value	$	—		$	(3.9	)		$	—		$	(3.9	)

________________________________

(1)	Balance includes $41.3 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisition-related escrows.

(2)	Balance relates to 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 months ended March 31, 2015, the Company had no transfers between levels of the fair value hierarchy of its assets or liabilities measured at fair value.

All of the Company's privately-held debt and redeemable preferred stock securities, are classified as Level 3 assets due to the absence of quoted market prices and an inherent lack of liquidity. The Company estimates the fair value of its privately-held debt investments on a recurring basis using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. During the three months ended March 31, 2015, there were purchases of $2.8 million related to privately-held debt securities.

Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis

Certain of the Company's assets, including intangible assets, goodwill, and privately-held equity investments, are measured at fair value on a nonrecurring basis, only if impairment is indicated. Privately-held equity investments, which are normally carried at cost, are measured at fair value on a nonrecurring basis due to events and circumstances that the Company identifies as significantly impacting the fair value of investments. The Company estimates the fair value of its privately-held equity investments using an analysis of the financial condition and near-term prospects of the investee, including recent financing activities and the investee's capital structure. Purchased intangible assets are measured at fair value primarily using discounted cash flow projections.

As of March 31, 2015, the Company had no assets measured at fair value on a nonrecurring basis. As of December 31, 2014, the Company recorded a goodwill impairment charge of $850.0 million for its Security reporting unit measured at fair value on a nonrecurring basis. The remeasurement of goodwill is classified as Level 3 value assessment due to the significance of unobservable inputs developed using company-specific information. As of December 31, 2014, the Company had no significant privately-held equity investments measured at fair value on a nonrecurring basis.

As of March 31, 2015 and December 31, 2014, the Company had no liabilities measured at fair value on a nonrecurring basis.

Assets and Liabilities Not Measured at Fair Value

The carrying amounts of the Company's accounts receivable, financing receivables, accounts payable, and other accrued liabilities approximate fair value due to their short maturities. As of March 31, 2015 and December 31, 2014, the estimated fair value of the Company's short-term and long-term debt in the Condensed Consolidated Balance Sheets was approximately $2,026.0 million and $1,395.2 million, respectively, based on observable market inputs (Level 2). As of March 31, 2015 and December 31, 2014, the estimated fair value of the Company's promissory note in connection with the sale of Junos Pulse recorded in other long term assets in the Condensed Consolidated Balance Sheet was $125.0 million classified as Level 3 assets due to the absence of quoted market prices and inherent lack of liquidity.

Derivative_Instruments

Derivative Instruments	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments	Derivative Instruments

	The Company uses derivatives to partially offset its market exposure to fluctuations in certain foreign currencies and does not enter into derivatives for speculative or trading purposes.

	The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions):


		As of
		March 31,		December 31,
		2015		2014
	Cash flow hedges	$	118.5	$	160.7

	Non-designated derivatives	78.4		78

	Total	$	196.9	$	238.7


	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, on 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 4, Fair Value Measurements, for the fair values of the Company's derivative instruments in the Condensed Consolidated Balance Sheets.

	As of March 31, 2015, the Company recognized a loss of $6.1 million in accumulated other comprehensive loss for the effective portion of its derivative instruments and reclassified a loss of $3.0 million during the three months ended March 31, 2015 from other comprehensive income to operating expense in the Condensed Consolidated Statements of Operations. As of March 31, 2014, the Company recognized a gain of $2.7 million in accumulated other comprehensive income for the effective portion of its derivative instruments and reclassified a gain of $1.0 million during the three months ended March 31, 2014 from other comprehensive loss 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 months ended March 31, 2015 and March 31, 2014.

	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 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. These foreign exchange forward contracts have maturities within two months.

	During the three months ended March 31, 2015 and March 31, 2014, the Company recognized a net gain of $2.1 million and a net loss of $0.6 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 March 31, 2015 and December 31, 2014, 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	3 Months Ended
	Mar. 31, 2015
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 three months ended March 31, 2015 (in millions):


	Balance as of December 31, 2014	$	2,981.50

	Other	(0.2		)
	Balance as of March 31, 2015	$	2,981.30


	There were no impairments to goodwill during the three months ended March 31, 2015 and March 31, 2014.

	Purchased Intangible Assets

	The Company’s purchased intangible assets were as follows (in millions):


		Gross			Accumulated			Impairments and			Net
					Amortization			Other Charges
	As of March 31, 2015
	Intangible assets with finite lives:
	Technologies and patents	$	567.7		$	(477.2	)	$	(49.9	)	$	40.6

	Customer contracts, support agreements, and	78.1			(66.0		)	(2.8		)	9.3
	related relationships
	Other	1.1			(0.5		)	—			0.6

	Total purchased intangible assets	$	646.9		$	(543.7	)	$	(52.7	)	$	50.5


	As of December 31, 2014
	Intangible assets with finite lives:
	Technologies and patents	$	567.7		$	(466.1	)	$	(49.9	)	$	51.7

	Customer contracts, support agreements, and	78.1			(65.2		)	(2.8		)	10.1
	related relationships
	Other	1.1			(0.5		)	—			0.6

	Total purchased intangible assets	$	646.9		$	(531.8	)	$	(52.7	)	$	62.4


	The following table presents the amortization of intangible assets included in the Condensed Consolidated Statements of Operations (in millions):


		Three Months Ended March 31,
		2015			2014
	Cost of revenues	$	10.8		$	8.2

	Operating expenses:
	Sales and marketing	0.8			1

	General and administrative	0.3			0.3

	Total operating expenses	1.1			1.3

	Total	$	11.9		$	9.5


	During the three months ended March 31, 2015, the Company recorded $5.6 million to cost of revenues in the Condensed Consolidated Statements of Operations, related to the acceleration of the end-of-life of certain intangible assets.

	There were no impairment charges related to purchased intangible assets during the three months ended March 31, 2015 and March 31, 2014.

As of March 31, 2015, the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions):


Years Ending December 31,	Amount
Remainder of 2015	$	16.6

2016	11.6

2017	7

2018	5.1

2019	4.9

Thereafter	5.3

Total	$	50.5

Other_Financial_Information

Other Financial Information	3 Months Ended
	Mar. 31, 2015
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 to be used in the manufacturing process and finished goods inventory in transit. Inventories are reported both within prepaid expenses and other current assets and other long-term assets in the Condensed Consolidated Balance Sheets. Total inventories consisted of the following (in millions):


		As of
		March 31,				December 31,
		2015				2014
	Production materials	$	49.3			$	38.3

	Finished goods	19.5				24.2

	Inventories	$	68.8			$	62.5


	In connection with the 2014 Restructuring Plan discussed in Note 8, Restructuring and Other Charges, the Company commenced a product rationalization initiative and accelerated the end-of-service life of certain products resulting in inventory charges of $8.4 million recorded within cost of revenues in the Condensed Consolidated Statement of Operations during the three months ended March 31, 2014.

	Other Long-Term Assets

	Other long-term assets consisted of the following (in millions):


		As of
		March 31,				December 31,
		2015				2014
	Privately-held investments	$	93.1			$	89.9

	Licensed software	8.3				8.6

	Federal income tax receivable	28.9				20

	Customer financing receivable	4.5				16.9

	Inventory	9.8				8

	Prepaid costs, deposits, and other	63.7				35.5

	Promissory note in connection with the sale of Junos Pulse(1)	125				125

	Other long-term assets	$	333.3			$	303.9

	_______________________________

	(1)	On October 1, 2014, the Company completed the sale of its Junos Pulse product portfolio. The Company received total consideration of $230.7 million, of which $105.7 million was in cash, net of a $19.3 million working capital adjustment, and $125.0 million was in the form of an 18-month non-contingent interest bearing promissory note issued to the Company.

	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 three months ended March 31, 2015 were as follows (in millions):


	Balance as of December 31, 2014	$	28.7

	Provisions made during the period	7.3

	Actual costs incurred during the period	(7.1		)
	Balance as of March 31, 2015	$	28.9


	Deferred Revenue

	Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):


	As of
	March 31,				December 31,
	2015				2014
Deferred product revenue:
Undelivered product commitments and other product deferrals	$	229.5			$	180.3

Distributor inventory and other sell-through items	90				103.7

Deferred gross product revenue	319.5				284

Deferred cost of product revenue	(66.1		)		(58.4		)
Deferred product revenue, net	253.4				225.6

Deferred service revenue	921.3				850.1

Total	$	1,174.70			$	1,075.70

Reported as:
Current	$	855.5			$	780.8

Long-term	319.2				294.9

Total	$	1,174.70			$	1,075.70


Deferred product revenue represents unrecognized revenue related to shipments to distributors that have not sold through to end-users, undelivered product commitments, and other shipments that have not met all revenue recognition criteria. In circumstances when costs are deferred, deferred product revenue is recorded net of the related costs of product revenue. Deferred service revenue represents billable amounts for service contracts, which include technical support, hardware and software maintenance, professional services, and training, for which services have not been rendered.

Other (Expense) Income, Net

Other (expense) income, net, consisted of the following (in millions):


	Three Months Ended March 31,
	2015				2014
Interest income	$	3.8			$	2.1

Interest expense	(18.5		)		(15.5		)
Gain on investments	0.6				166.2

Other	(1.7		)		1.4

Other (expense) income, net	$	(15.8	)		$	154.2


Interest income primarily includes interest earned on the Company’s cash, cash equivalents, investments, and on the promissory note issued to the Company in connection with the sale of Junos Pulse. Interest expense primarily includes interest, net of capitalized interest expense, from short-term debt, long-term debt, and customer financing arrangements. Other typically consists of investment and foreign exchange gains and losses and other non-operational income and expense items.

During the three months ended March 31, 2014, the Company recorded a gain of $163.0 million primarily related to the sale of investments which were converted from privately-held investments to publicly-traded equity upon initial public offering and subsequently sold.

Restructuring_and_Other_Charge

Restructuring and Other Charges	3 Months Ended
	Mar. 31, 2015
Restructuring Charges [Abstract]
Restructuring and Other Charges	Restructuring and Other Charges

	2014 Restructuring Plan and Other Restructuring Plans

	In the first quarter of 2014, the Company initiated a restructuring plan (the “2014 Restructuring Plan”) designed to refocus the Company's strategy, optimize its structure, and improve operational efficiencies. The 2014 Restructuring Plan consisted of workforce reductions, facility consolidations and closures, asset write-downs, contract terminations and other charges. The Company had also initiated restructuring plans in each of the fiscal years from 2011 through 2013 (the "Other Restructuring Plans") which focused on improving the Company's cost structure through product portfolio rationalizations, workforce reductions, contract terminations, project cancellations, and facility closures and consolidations. As of March 31, 2015, the Company's restructuring plans have been substantially completed and the Company does not expect to record significant future charges under any of these restructuring plans.

	The following table presents restructuring and other charges included in cost of revenues and restructuring and other charges in the Condensed Consolidated Statements of Operations under the Company's restructuring plans (in millions):


		Three Months Ended March 31,
		2015			2014
	Severance	$	1.5		$	28.3

	Facilities	(0.1		)	0.2

	Contract terminations	—			0.8

	Asset impairment and write-downs	—			93.1

	Total	$	1.4		$	122.4


	Reported as:
	Cost of revenues	$	—		$	8.4

	Restructuring and other charges	1.4			114

	Total	$	1.4		$	122.4


	During the three months ended March 31, 2015, the Company recorded charges of $1.5 million for severance and a benefit of $0.1 million for facility consolidation and closures that were recorded to restructuring and other charges in the Condensed Consolidated Statements of Operations, related to the 2014 Restructuring Plan.

	During the three months ended March 31, 2014, the Company recorded $28.0 million of severance costs, $84.7 million of impairment charges related to licensed software, and $0.8 million of charges related to contract terminations, which were recorded in restructuring and other charges in the Condensed Consolidated Statements of Operations, in connection with the 2014 Restructuring Plan. The Company also recorded inventory write-downs related to the acceleration of the end-of-service life of certain products totaling $8.4 million which were recorded in cost of revenues in the Condensed Consolidated Statements of Operations during the three months ended March 31, 2014, in connection with the 2014 Restructuring Plan. The Company recorded minor adjustments during the three months ended March 31, 2014 in connection with the Other Restructuring Plans.

	Restructuring and other charges noted above are based on the 2014 Restructuring Plan and Other Restructuring Plans that were committed to by management. Any changes in the estimates of executing the approved restructuring plans are reflected in the Company's results of operations.

	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 three months ended March 31, 2015 (in millions):


		December 31,			Charges			Cash			Non-cash			March 31,
		2014						Payments			Settlements and			2015
											Other
	Severance	$	9.4		$	1.5		$	(5.9	)	$	(0.4	)	$	4.6

	Facilities	7.4			(0.1		)	(2.3		)	(0.4		)	4.6

	Contract terminations and other	0.2			—			—			—			0.2

	Total	$	17		$	1.4		$	(8.2	)	$	(0.8	)	$	9.4


	As of March 31, 2015, the Company's restructuring liability was $9.4 million, of which $4.8 million is related to severance and other charges expected to be settled by September 2015. The remaining $4.6 million, which is primarily related to facility closures, is expected to be paid through March 2018.

Debt_and_Financing

Debt and Financing	3 Months Ended
	Mar. 31, 2015
Debt Instruments [Abstract]
Debt and Financing	Debt and Financing

	Debt

	The following table summarizes the Company's short-term and long-term debt (in millions, except percentages):


		As of March 31, 2015
		Amount			Effective Interest
					Rates
	Senior Notes:
	3.10% fixed-rate notes, due March 2016	$	300		3.25	%

	3.30% fixed-rate notes, due June 2020	300			3.47	%

	4.60% fixed-rate notes, due March 2021	300			4.69	%

	4.50% fixed-rate notes, due March 2024	350			4.63	%

	4.35% fixed-rate notes, due June 2025	300			4.47	%

	5.95% fixed-rate notes, due March 2041	400			6.03	%

	Total senior notes	1,950.00

	Unaccreted discount	(1.4		)
	Total	$	1,948.60


	Reported as:
	Short-term debt	$	299.9

	Long-term debt	1,648.70

	Total	$	1,948.60


	In March 2015, the Company issued $300.0 million aggregate principal amount of 3.30% senior notes due 2020 ("2020 Notes") and $300.0 million aggregate principal amount of 4.35% senior notes due 2025 ("2025 Notes"). In March 2014, the Company issued $350.0 million aggregate principal amount of 4.50% senior notes due 2024 ("2024 Notes"). In March 2011, the Company issued $300.0 million aggregate principal amount of 3.10% senior notes due 2016 ("2016 Notes"), $300.0 million aggregate principal amount of 4.60% senior notes due 2021 ("2021 Notes"), and $400.0 million aggregate principal amount of 5.95% senior notes due 2041 ("2041 Notes").

	The "2016 Notes," "2020 Notes," "2021 Notes," "2024 Notes," "2025 Notes" and "2041 Notes" collectively the "Notes" are the Company’s senior unsecured and unsubordinated obligations, ranking equally in right of payment to all of the Company’s existing and future senior unsecured and unsubordinated indebtedness and senior in right of payment to any of the Company’s future indebtedness that is expressly subordinated to the Notes.

	The Company may redeem the 2020 Notes and 2025 Notes, either in whole or in part, at any time one month prior to the maturity date of the 2020 Notes, and three months prior to the maturity date of the 2025 Notes, at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the 2020 Notes and 2025 Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted at the Treasury rate plus 30 basis points for the 2020 Notes, or the Treasury rate plus 37.5 basis points for the 2025 Notes, plus, in the case of each of the clauses (i) and (ii) above, accrued and unpaid interest, if any. At any time on or after May 15, 2020, in the case of the 2020 Notes, and at any time on or after March 15, 2025, in the case of the 2025 Notes, the Company may redeem Notes of such series, in whole or in part, at a redemption price equal to 100% of the principal amount of the 2020 Notes and the 2025 Notes to be redeemed, plus accrued and unpaid interest, if any. The Company may redeem the other Notes, either in whole or in part, at any time at a redemption price equal to the greater of (i) 100% of the aggregate principal amount of the Notes to be redeemed or (ii) the sum of the present values of the remaining scheduled payments discounted to the redemption date, plus, in either case, accrued and unpaid interest, if any.

	In the event of a change of control repurchase event, the holders of the Notes may require the Company to repurchase for cash all or part of the Notes at a purchase price equal to 101% of the aggregate principal amount, plus accrued and unpaid interest, if any.

	Interest on the Notes is payable in cash semiannually. The effective interest rates for the Notes include the interest on the Notes, accretion of the discount, and amortization of issuance costs. The indentures that govern the Notes also contain various covenants, including limitations on the Company's ability to incur liens or enter into sale-leaseback transactions over certain dollar thresholds.

	As of March 31, 2015, the Company was in compliance with all covenants in the indentures governing the Notes.

	Revolving Credit Facility

	On June 27, 2014, the Company entered into a Credit Agreement ("Credit Agreement") with certain institutional lenders and Citibank, N.A., as administrative agent, that provides for a $500.0 million unsecured revolving credit facility, with an option of the Company to increase the amount of the credit facility by up to an additional $200.0 million, subject to certain conditions. Proceeds of loans made under the Credit Agreement may be used by the Company for working capital and general corporate purposes. Revolving loans may be borrowed, repaid and reborrowed until June 27, 2019, at which time all amounts borrowed must be repaid. Borrowings 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 March 31, 2015, the Company was in compliance with all covenants in the Credit Agreement, and no amounts were outstanding.

	Customer Financing Arrangements

	The Company provides certain distribution partners access to extended financing arrangements for certain end-user customers that require longer payment terms than those typically provided by the Company through factoring accounts receivable to third-party financing providers ("financing providers"). The program does not and is not intended to affect the timing of the Company's revenue recognition. Under the financing arrangements, proceeds from the financing provider are due to the Company within 30 to 90 days from the sale of the receivable. In these transactions with the financing provider, the Company surrenders control over the transferred assets. 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. In 2014, the Company transitioned certain distribution partners from the third party financing program to the Company's commercial payment terms. As a result the Company's customer financing activities significantly declined from fiscal year 2014 to the first quarter of 2015.

	Pursuant to the financing arrangements for the sale of receivables, the Company sold net receivables of $47.1 million and $133.0 million during the three months ended March 31, 2015 and March 31, 2014, respectively.

	The Company received cash proceeds from the financing provider of $60.0 million and $192.3 million during the three months ended March 31, 2015 and March 31, 2014, respectively. As of March 31, 2015 and December 31, 2014, the amounts owed to the Company by the financing provider were $15.1 million and $28.0 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 March 31, 2015, the Company has not been required to make any payments under these arrangements. Pursuant to these arrangements, the Company has guarantees for third-party financing arrangements of $11.1 million as of March 31, 2015.

The portion of the receivable financed that has not been recognized as revenue is accounted for as a financing arrangement and is included in other accrued liabilities and other long-term liabilities in the Condensed Consolidated Balance Sheets. As of March 31, 2015 and December 31, 2014, the estimated cash received from the financing provider not recognized as revenue was $13.3 million and $67.5 million, respectively.

Equity

Equity	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Equity	Equity

	Cash Dividends on Shares of Common Stock

	On January 27, 2015, the Company declared a quarterly cash dividend of $0.10 per share of common stock, or $40.8 million in the aggregate, to stockholders of record on March 3, 2015 which was paid on March 24, 2015. Any future dividends, and the establishment of record and payment dates, are subject to approval by the Board of Directors (the "Board") of Juniper Networks or authorized committee thereof. See Note 16, Subsequent Events, for discussion of the Company's dividend declaration subsequent to March 31, 2015.

	Stock Repurchase Activities

	In February 2014, the Company's Board approved a stock repurchase program that authorized the Company to repurchase up to $2.1 billion of its common stock, including $1.2 billion pursuant to an accelerated share repurchase program ("2014 Stock Repurchase Program"). In October 2014, the Board authorized a $1.3 billion increase to the 2014 Stock Repurchase Program for a total of $3.4 billion.

	During the three months ended March 31, 2015, the Company repurchased and retired approximately 17.4 million shares of its common stock under the 2014 Stock Repurchase Program at an average price of $23.05 per share for an aggregate purchase price of $400.0 million during the three months ended March 31, 2015.

	During the three months ended March 31, 2014, the Company entered into two separate accelerated share repurchase agreements (collectively, the "ASR") with two financial institutions to repurchase an aggregate of $1.2 billion of the Company's common stock. During the first quarter of 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. 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. The shares received with respect to the ASR have been retired. Retired shares return to authorized but unissued shares of common stock.

	As of March 31, 2015, there was $775.0 million of authorized funds remaining under the 2014 Stock Repurchase Program. The Company intends to repurchase $600.0 million of its common stock during 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 months ended March 31, 2015 and March 31, 2014.

	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 16, Subsequent Events, for discussion of the Company's stock repurchase activity subsequent to March 31, 2015.

	Accumulated Other Comprehensive Income, Net of Tax

	The components of accumulated other comprehensive income, net of related taxes, during the three months ended March 31, 2015 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, 2014	8.4		(4.2	)	(18.0	)	(13.8	)

	Other comprehensive loss before reclassifications	(0.8	)	(6.4	)	(11.1	)	(18.3	)
	Amount reclassified from accumulated other	(0.2	)	3.1		—		2.9
	comprehensive income
	Other comprehensive loss, net	(1.0	)	(3.3	)	(11.1	)	(15.4	)
	Balance as of March 31, 2015	7.4		(7.5	)	(29.1	)	(29.2	)

	________________________________

	(1)	The reclassifications out of accumulated other comprehensive income during the three months ended March 31, 2015 for realized gains on available-for-sale securities of $0.2 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 three months ended March 31, 2015 for realized losses on cash flow hedges are included within cost of revenues of $0.9 million, sales and marketing of $2.1 million, and general and administrative of $0.2 million and for realized gains of $0.1 million within research and development for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.

Employee_Benefit_Plans

Employee Benefit Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Employee Benefit Plans	Employee Benefit Plans

	Equity Incentive Plans

	The Company’s equity incentive plans include the 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 March 31, 2015, an aggregate of 27.8 million shares were subject to currently outstanding equity awards under the 2006 Plan and the 1996 Plan, and no shares were subject to currently outstanding equity awards under the 2000 Plan. As of March 31, 2015, 36.2 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 March 31, 2015, approximately 17.1 million shares have been issued and 1.9 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 March 31, 2015, stock options, RSUs, RSAs and PSAs representing approximately 3.3 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 three months ended March 31, 2015 (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, 2014	9.9			$	24.87

	Canceled	(0.1	)		23.52

	Exercised	(0.3	)		14.2

	Expired	(1.7	)		26.32

	Balance as of March 31, 2015	7.8			$	25.05		2.1		$	22.3


	As of March 31, 2015:
	Vested and expected-to-vest options	7.8			$	25.17		2.1		$	21.5

	Exercisable options	7.3			$	26.23		1.8		$	14.7


	The aggregate intrinsic value represents the difference between the Company’s closing stock price on the last trading day of the period, which was $22.58 per share as of March 31, 2015, and the exercise price of the applicable options multiplied by the number of related options. The pre-tax intrinsic value of options exercised, representing the difference between the fair market value of the Company’s common stock on the date of exercise and the exercise price of each option, was $3.3 million for the three months ended March 31, 2015.

	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 three months ended March 31, 2015 (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, 2014	21.3			$	22.05

	RSUs granted (1)(3)	6.9			22.42

	PSAs granted (2)(3)	0.8			22.44

	RSUs vested	(3.2	)		23.75

	RSAs vested	(0.7	)		21.01

	PSAs vested	(0.2	)		22.6

	RSUs canceled	(0.8	)		22.11

PSAs canceled	(0.8	)		22.21

Balance as of March 31, 2015	23.3			$	21.94		1.5		$	525.9

________________________________

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

(2)	The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to these PSAs that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.5 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.

(3)	The grant date fair value of RSUs and PSAs were reduced by the present value of dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested. On January 27, 2015, the Company declared a cash dividend of $0.10 per share of common stock, or $40.8 million in the aggregate, to stockholders of record on March 3, 2015, which was paid on March 24, 2015.

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 1.5 million shares of common stock through the ESPP at an average exercise price of $19.32 and $18.67 per share for the three months ended March 31, 2015 and March 31, 2014, respectively.

Valuation Assumptions

The weighted-average assumptions used and the resulting estimates of fair value for ESPP and market-based RSUs during the three months ended March 31, 2015 and March 31, 2014 were as follows:


	Three Months Ended March 31,
	2015		2014
ESPP (1):
Volatility	30%		33%
Risk-free interest rate	0.10%		0.10%
Expected life (years)	0.5		0.5
Dividend yield	1.90%		—
Weighted-average fair value per share	$5.23		$6.37

Market-based RSUs (2):
Volatility	34%		36%
Risk-free interest rate	1.40%		1.60%
Dividend yield	0% - 1.8%		0% - 1.5%
Weighted-average fair value per share	14.97		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 March 31,
	2015				2014
Cost of revenues - Product	$	1.7			$	1.3

Cost of revenues - Service	3.4				4

Research and development	30.7				32.1

Sales and marketing	5.8				14.6

General and administrative	4.4				8.8

Total	$	46			$	60.8


The following table summarizes share-based compensation expense by award type (in millions):


	Three Months Ended March 31,
	2015				2014
Stock options	$	2.2			$	5.1

RSUs, RSAs, and PSAs	40.6				51.8

ESPP	3.2				3.9

Total	$	46			$	60.8


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 March 31, 2015 (in millions, except years):


	Unrecognized				Weighted Average
	Compensation Cost				Period
					(In Years)
Stock options	$	7.8			1.2

RSUs, RSAs, and PSAs	$	325.9			2.1

Segments

Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segments	Segments

	In 2014, the Company realigned its organization into a One-Juniper structure which includes consolidating each of the Company's R&D and go-to-market functions. As a result of these changes, the consolidated business is considered to be one reportable segment, consistent with how the Company’s chief operating decision maker ("CODM") views the business, allocates resources, and assesses the performance of the Company.

	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 March 31,
		2015		2014
	Routing	$	504.8	$	549.8

	Switching	166.5		192

	Security	92.8		134.2

	Total product	764.1		876


	Total service	303.3		294.1

	Total	$	1,067.40	$	1,170.10


	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 March 31,
		2015		2014
	Americas:
	United States	$	533.5	$	623.7

	Other	55.5		57.8

	Total Americas	589		681.5

	Europe, Middle East, and Africa	303.8		295.7

	Asia Pacific	174.6		192.9

	Total	$	1,067.40	$	1,170.10

	No customer accounted for 10% or more of the Company's net revenues during the three months ended March 31, 2015 and March 31, 2014, respectively.

	The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions):


		As of
		March 31,		December 31,
		2015		2014
	United States	$	871	$	871.7

	International	91.7		95

	Property and equipment, net and purchased intangible assets, net	$	962.7	966.7


	The Company tracks assets by physical location. The majority of the Company’s assets, excluding cash and cash equivalents and investments, as of March 31, 2015 and December 31, 2014, were attributable to U.S. operations.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes

	The Company's effective tax rate for the three months ended March 31, 2015 of 30.9% was lower than the federal statutory rate of 35% primarily due to the benefit of the Section 199 deduction for U.S. production activities, earnings in foreign jurisdictions, which are subject to lower tax rates, and the impact of the discrete items noted below. The effective rate for the period does not reflect the benefit of the federal research and development ("R&D") credit, which expired on December 31, 2014.

	The Company's effective tax rate for the three months ended March 31, 2014 of 25.3% was lower than the federal statutory rate of 35% primarily due to the benefit of the Section 199 deduction for U.S. production activities, earnings in foreign jurisdictions, which are subject to lower tax rates, and the impact of the discrete items noted below. 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 rates for the three months ended March 31, 2015 and March 31, 2014 include the tax expense (benefit) of the following discrete items (in millions):


		Three Months Ended March 31,
		2015			2014
	Tax on equity investments(1)	$	—		$	35.6

	Restructuring	$	(1.3	)	$	(30.8	)
	________________________________
	(1) During the three months ended March 31, 2014, tax on equity investments of $35.6 million is net of a valuation allowance release of $24.7 million.

	As of March 31, 2015, the total amount of gross unrecognized tax benefits was $201.3 million, of which $167.3 million, if recognized, would affect the Company's effective tax rate.

	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 $3.1 million within the next twelve months due to lapses of applicable statutes of limitations and the completion of tax review cycles in various tax jurisdictions.

	The Company is currently under examination by the Internal Revenue Service ("IRS") for the 2007 through 2009 tax years and the California Franchise Tax Board for the 2004 through 2006 tax years. During the first quarter of 2015, the IRS issued “Notices of Proposed Adjustments” ("NOPA’s") related to the examination. The Company regularly assesses the likelihood of an adverse outcome resulting from such examinations. As of March 31, 2015, the Company believes the resolution of the audits will not have a material adverse impact on the financial statements.

	The Company is also subject to separate ongoing examinations by the India tax authorities for the 2004 tax year, 2004 through 2008 tax years, and the 2008 through 2010 tax years.

	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 not aware of any other examinations by tax authorities in any other major jurisdictions in which it files income tax returns as of March 31, 2015.

	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	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Net Income Per Share	Net Income Per Share

	The Company computed basic and diluted net income per share attributable to Juniper Networks common stockholders as follows (in millions, except per share amounts):


		Three Months Ended March 31,
		2015		2014
	Numerator:
	Net income	$	80.2	$	110.6

	Denominator:
	Weighted-average shares used to compute basic net income per share	407.1		486.2

	Dilutive effect of employee stock awards	7.1		10.3

	Weighted-average shares used to compute diluted net income per share	414.2		496.5

	Net income per share attributable to Juniper Networks common stockholders:
	Basic	$	0.2	$	0.23

	Diluted	$	0.19	$	0.22


	Anti-dilutive:
	Potential anti-dilutive shares	6.4		25.4


	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	3 Months Ended
Commitments and Contingencies	Mar. 31, 2015
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 $132.0 million as of March 31, 2015. Rent expense was $11.5 million and $13.0 million for the three months ended March 31, 2015, and March 31, 2014, 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 $388.6 million as of March 31, 2015.

	The Company establishes a liability in connection with purchase commitments related to quantities in excess of its demand forecasts or obsolete materials charges for components purchased by the contract manufacturers based on the Company’s demand forecast or customer orders. As of March 31, 2015, the Company accrued $23.0 million based on its estimate of such charges. This includes $8.8 million related to net losses on firm and non-cancelable purchase commitments.

	Debt and Interest Payment on Debt

	As of March 31, 2015, the Company held short-term and long-term debt consisting of senior notes with a carrying value of $299.9 million and $1,648.7 million, respectively. Of these Notes, $300.0 million will mature in 2016 and bears interest at a fixed rate of 3.10%, $300.0 million will mature in 2020 and bears interest at a rate of 3.30%, $300.0 million will mature in 2021 and bears interest at a fixed rate of 4.60%, $350.0 million will mature in 2024 and bears interest at a fixed rate of 4.50%, $300.0 million will mature in 2025 and bears interest at a fixed rate of 4.35%, and $400.0 million will mature in 2041 and bears interest at a fixed rate of 5.95%. Interest on the Notes is payable semiannually. See Note 9, Debt and Financing, for further discussion of the Company's short-term and long-term debt.

	Other Contractual Obligations

	As of March 31, 2015, other contractual obligations primarily consisted of (1) $46.0 million in indemnity and employee-related obligations and service-related escrows, including those required in connection with certain asset purchases and acquisitions completed by the Company between 2005 and 2014; (2) $3.5 million in campus build-out obligations; and (3) $29.6 million of agreements that include firm and non-cancelable terms to transfer funds in the future for fixed or minimum amounts or quantities to be purchased at fixed or minimum prices.
	Tax Liabilities

	As of March 31, 2015, the Company had $178.9 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 March 31, 2015 and December 31, 2014, the Company had $16.3 million and $26.2 million, respectively, in financing arrangements, bank guarantees, and standby letters of credit related to these financial guarantees, of which $11.1 million in financing guarantees was recorded in other accrued liabilities and other long-term liabilities in the Condensed Consolidated Balance Sheets as of March 31, 2015. See Note 9, Debt and Financing, for further discussion of the Company's third-party customer financing arrangements that contain guarantee provisions.

	Legal Proceedings

	Investigations

	The U.S. Securities and Exchange Commission (SEC) and the U.S. Department of Justice (DOJ) are conducting investigations into possible violations by the Company of the U.S. Foreign Corrupt Practices Act (FCPA). The Company is cooperating with these agencies regarding these matters. The Company’s Audit Committee, with the assistance of independent advisors, has been investigating and conducting a thorough review of possible violations of the FCPA, and has made recommendations for remedial measures, including employee disciplinary actions in foreign jurisdictions, which the Company has implemented and continues to implement. The Company is unable to predict the duration, scope or outcome of the SEC and DOJ investigations, but believes that an adverse outcome is reasonably possible. However, the Company is not able to estimate a reasonable range of possible loss. The SEC and/or DOJ could take action against us or we could agree to settle. In such event, we could be required to pay substantial fines and sanctions and/or implement additional remedial measures; in addition, it may be determined that we violated the FCPA.

	Other Litigation

	In addition to the investigations discussed above, the Company is involved in other disputes, litigation, and other legal actions. The Company is aggressively defending these current litigation matters, and while there can be no assurances and the outcome of these matters is currently not determinable, and the Company currently believes that none of these existing claims or proceedings are likely to have a material adverse effect on its financial position. There are many uncertainties associated with any litigation and these actions or other third-party claims against the Company may cause the Company to incur costly litigation and/or substantial settlement charges. In addition, the resolution of any intellectual property litigation may require the Company to make royalty payments, which could adversely affect gross margins in future periods. If any of those events were to occur, the Company's business, financial condition, results of operations, and cash flows could be adversely affected. The actual liability in any such matters may be materially different from the Company's estimates, if any, which could result in the need to adjust the liability and record additional expenses.

	We record an accrual for loss contingencies for legal proceedings when we believe that an unfavorable outcome is both (a) probable and (b) the amount or range of any possible loss is reasonably estimable. We have not recorded any accrual for loss contingencies associated with such legal proceedings or the investigations discussed above.

Subsequent_Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events

	Dividend Declaration

	On April 23, 2015, the Company announced that it had declared a cash dividend of $0.10 per share of common stock payable on June 23, 2015 to stockholders of record as of the close of business on June 2, 2015.

	Stock Repurchase Activities

	Subsequent to March 31, 2015, through the filing of this Report, the Company repurchased 12.8 million shares of its common stock, for an aggregate of $315.0 million at an average purchase price of $24.54 per share, under the 2014 Stock Repurchase Program. Repurchases of 11.7 million shares were settled prior to the filing of this Report and the remaining shares will be settled after the filing date. Under the 2014 Stock Repurchase Program, the Company has $460.0 million authorized funds remaining as of the filing date. Purchases under the Company's stock repurchase program are subject to review of the circumstances in place at the time and will be made from time to time as permitted by securities laws and other legal requirements. This program may be discontinued at any time.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2015
Accounting Policies [Abstract]
Recent accounting pronouncements	Recent Accounting Pronouncements

	In April 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2015-05 (Subtopic 350-40) - Customer's Accounting for Fees Paid in a Cloud Computing Arrangement, which provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 is effective for fiscal years, beginning after December 15, 2015. Early adoption is permitted. The Company is currently evaluating the impact of the adoption on its Condensed Consolidated Financial Statements, if any.

	In April 2015, the FASB issued ASU No. 2015-03 (Subtopic 835-30) - Simplifying the Presentation of Debt Issuance Costs, which requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. ASU 2015-03 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard would reduce the debt issuance cost asset on the Company's Condensed Consolidated Balance Sheet by approximately $11.0 million and correspondingly reduce its debt liabilities by approximately $11.0 million. The Company plans to adopt this standard in the first quarter of 2016. There would be no impact to the Condensed Consolidated Statement of Operations.

	In January 2015, the FASB issued ASU No. 2015-01 (Subtopic 225-20) - Income Statement - Extraordinary and Unusual Items, which eliminates the concept of extraordinary items. ASU 2015-01 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. Early adoption is permitted. The adoption of this standard will not have an impact on the Company's Condensed Consolidated Financial Statements.

	In November 2014, the FASB issued ASU No. 2014-16 (Topic 815) - Derivatives and Hedging, which provides clarification on how current guidance should be interpreted in evaluating the economic characteristics and risks of a host contract in a hybrid financial instrument that is issued in the form of a share. Specifically, the amendments clarify that an entity should consider all relevant terms and features in evaluating the host contract and that no single term or feature would necessarily determine the economic characteristics and risks of the host contract. ASU 2014-16 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2015. The amendment should be applied on a modified retrospective basis to existing hybrid financial instruments issued in the form of a share as of the beginning of the year for which the amendments are effective. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the Company's Condensed Consolidated Financial Statements.

	In August 2014, the FASB issued 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 Condensed 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 Condensed 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. In April 2015, the FASB proposed to defer the effective date of the new revenue standard by one year. As a result, the Company would apply the new revenue standard for annual and interim periods beginning after December 15, 2017, with early adoption permitted before annual periods beginning after December 15, 2016. 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 Condensed Consolidated Financial Statements.

Cash_Equivalents_and_Investmen1

Cash Equivalents and Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Cash Equivalents and Investments [Abstract]
Unrealized gains and losses and fair value of available-for-sale and trading securities	The following tables summarize the Company's unrealized gains and losses and fair value of investments designated as available-for-sale and trading securities as of March 31, 2015 and December 31, 2014 (in millions):


		Amortized			Gross Unrealized				Gross Unrealized				Estimated Fair
		Cost			Gains				Losses				Value
	As of March 31, 2015
	Fixed income securities:
	Asset-backed securities	$	308.9		$	0.1			$	(0.2	)		$	308.8

	Certificates of deposit	8.2			—				—				8.2

	Commercial paper	15.6			—				—				15.6

	Corporate debt securities	843.2			1.1				(0.5		)		843.8

	Foreign government debt securities	34.7			—				—				34.7

	Government-sponsored enterprise obligations	190.3			0.1				—				190.4

	U.S. government securities	233.7			0.2				—				233.9

	Total fixed income securities	1,634.60			1.5				(0.7		)		1,635.40

	Money market funds	776.2			—				—				776.2

	Mutual funds	4			0.1				—				4.1

	Publicly-traded equity securities	2			0.6				—				2.6

	Total available-for-sale securities	2,416.80			2.2				(0.7		)		2,418.30

	Trading securities in mutual funds(1)	17.7			—				—				17.7

	Total	$	2,434.50		$	2.2			$	(0.7	)		$	2,436.00


	Reported as:
	Cash equivalents	$	750.8		$	—			$	—			$	750.8

	Restricted investments	45.3			0.1				—				45.4

	Short-term investments	397.5			0.8				(0.1		)		398.2

	Long-term investments	1,240.90			1.3				(0.6		)		1,241.60

	Total	$	2,434.50		$	2.2			$	(0.7	)		$	2,436.00

	________________________________

	(1)	Balance consists of the Company's non-qualified deferred compensation plan assets.


		Amortized			Gross Unrealized				Gross Unrealized				Estimated Fair
		Cost			Gains				Losses				Value
	As of December 31, 2014
	Fixed income securities:
	Asset-backed securities	$	269.3		$	—			$	(0.3	)		$	269

	Certificates of deposit	10.6			—				—				10.6

	Commercial paper	20.3			—				—				20.3

	Corporate debt securities	738.6			0.5				(1.1		)		738

Foreign government debt securities	24.6			—				—				24.6

Government-sponsored enterprise obligations	162.2			—				(0.1		)		162.1

U.S. government securities	246.1			—				(0.1		)		246

Total fixed income securities	1,471.70			0.5				(1.6		)		1,470.60

Money market funds	594.2			—				—				594.2

Mutual funds	3.9			0.1				—				4

Publicly-traded equity securities	2.1			—				(0.1		)		2

Total available-for-sale securities	2,071.90			0.6				(1.7		)		2,070.80

Trading securities in mutual funds(1)	16.3			—				—				16.3

Total	$	2,088.20		$	0.6			$	(1.7	)		$	2,087.10


Reported as:
Cash equivalents	$	576.6		$	—			$	—			$	576.6

Restricted investments	45.2			—				—				45.2

Short-term investments	332.2			0.2				(0.2		)		332.2

Long-term investments	1,134.20			0.4				(1.5		)		1,133.10

Total	$	2,088.20		$	0.6			$	(1.7	)		$	2,087.10


________________________________

(1)	Balance consists of 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 March 31, 2015 (in millions):


		Amortized			Gross Unrealized				Gross Unrealized				Estimated Fair
		Cost			Gains				Losses				Value
	Due in less than one year	$	393.7		$	0.2			$	(0.1	)		$	393.8

	Due between one and five years	1,240.90			1.3				(0.6		)		1,241.60

	Total	$	1,634.60		$	1.5			$	(0.7	)		$	1,635.40

Available-for-sale securities in unrealized loss position	The following tables present the Company's available-for-sale securities that were in an unrealized loss position as of March 31, 2015 and December 31, 2014 (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 March 31, 2015
	Fixed income securities:
	Asset-backed securities(1)	$	222.4		$	(0.2	)		$	1.7			$	—	$	224.1	$	(0.2	)

	Corporate debt securities	391.5			(0.5		)		—				—		391.5		(0.5		)

	Foreign government debt securities(2)	29.1			—				—				—		29.1		—

	Government-sponsored enterprise obligations(2)	60.4			—				—				—		60.4		—

	U.S. government securities(2)	47.5			—				—				—		47.5		—

	Total fixed income securities	750.9			(0.7		)		1.7				—		752.6		(0.7		)

	Total available-for-sale securities	$	750.9		$	(0.7	)		$	1.7			$	—	$	752.6	$	(0.7	)

	________________________________
	(1) Balances greater than 12 months include investments that were in an immaterial unrealized loss position as of March 31, 2015.
	(2) Balances less than 12 months include investments that were in an immaterial unrealized loss position as of March 31, 2015.



		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, 2014
	Fixed income securities:
	Asset-backed securities	$	221.9		$	(0.3	)		$	—			$	—	$	221.9	$	(0.3	)

	Corporate debt securities	515.9			(1.1		)		—				—		515.9		(1.1		)

	Foreign government debt securities(1)	24.6			—				—				—		24.6		—

	Government-sponsored enterprise obligations	113.8			(0.1		)		—				—		113.8		(0.1		)

	U.S. government securities	189			(0.1		)		—				—		189		(0.1		)

	Total fixed income securities	1,065.20			(1.6		)		—				—		1,065.20		(1.6		)

	Publicly-traded equity securities	2			(0.1		)		—				—		2		(0.1		)

	Total available-for-sale securities	$	1,067.20		$	(1.7	)		$	—			$	—	$	1,067.20	$	(1.7	)

	________________________________

	(1)	Balances less than 12 months include investments that were in an immaterial unrealized loss position as of December 31, 2014.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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 March 31, 2015 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	$	—		$	308.8			$	—		$	308.8

	Certificates of deposit	—			8.2				—			8.2

	Commercial paper	—			15.6				—			15.6

	Corporate debt securities	—			843.8				—			843.8

	Foreign government debt securities	—			34.7				—			34.7

	Government-sponsored enterprise obligations	—			190.4				—			190.4

	Money market funds(1)	776.2			—				—			776.2

	Mutual funds(2)	4.1			—				—			4.1

	Publicly-traded equity securities	2.6			—				—			2.6

	U.S. government securities	221.6			12.3				—			233.9

	Total available-for-sale securities	1,004.50			1,413.80				—			2,418.30

	Trading securities in mutual funds(3)	17.7			—				—			17.7

	Privately-held debt and redeemable preferred stock	—			—				50.3			50.3
	securities
	Derivative assets:
	Foreign exchange contracts	—			0.5				—			0.5

	Total assets measured at fair value	$	1,022.20		$	1,414.30			$	50.3		$	2,486.80

	Liabilities measured at fair value:
	Derivative liabilities:
	Foreign exchange contracts	$	—		$	(6.7	)		$	—		$	(6.7	)

	Total liabilities measured at fair value	$	—		$	(6.7	)		$	—		$	(6.7	)


	Total assets measured at fair value, reported as:
	Cash equivalents	$	735		$	15.8			$	—		$	750.8

	Restricted investments	45.4			—				—			45.4

	Short-term investments	65.2			333				—			398.2

	Long-term investments	176.6			1,065.00				—			1,241.60

	Prepaid expenses and other current assets	—			0.5				—			0.5

	Other long-term assets	—			—				50.3			50.3

	Total assets measured at fair value	$	1,022.20		$	1,414.30			$	50.3		$	2,486.80


Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—		$	(6.7	)		$	—		$	(6.7	)

Total liabilities measured at fair value	$	—		$	(6.7	)		$	—		$	(6.7	)

________________________________

(1)	Balance includes $41.2 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisition-related escrows.

(2)	Balance relates to 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, 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	$	—		$	269			$	—		$	269

Certificates of deposit	—			10.6				—			10.6

Commercial paper	—			20.3				—			20.3

Corporate debt securities	—			738				—			738

Foreign government debt securities	—			24.6				—			24.6

Government-sponsored enterprise obligations	—			162.1				—			162.1

Money market funds(1)	594.2			—				—			594.2

Mutual funds(2)	4			—				—			4

Publicly-traded equity securities	2			—				—			2

U.S. government securities	246			—				—			246

Total available-for-sale securities	846.2			1,224.60				—			2,070.80

Trading securities in mutual funds(3)	16.3			—				—			16.3

Privately-held debt and redeemable preferred stock	—			—				47.5			47.5
securities
Derivative assets:
Foreign exchange contracts	—			0.1				—			0.1

Total assets measured at fair value	$	862.5		$	1,224.70			$	47.5		$	2,134.70

Liabilities measured at fair value:
Derivative liabilities:
Foreign exchange contracts	$	—		$	(3.9	)		$	—		$	(3.9	)

Total liabilities measured at fair value	$	—		$	(3.9	)		$	—		$	(3.9	)


Total assets measured at fair value, reported as:
Cash equivalents	$	552.9		$	23.7			$	—		$	576.6

Restricted investments	45.2			—				—			45.2

Short-term investments	87			245.2				—			332.2

Long-term investments	177.4			955.7				—			1,133.10

Prepaid expenses and other current assets	—			0.1				—			0.1

Other long-term assets	—			—				47.5			47.5

Total assets measured at fair value	$	862.5		$	1,224.70			$	47.5		$	2,134.70


Total liabilities measured at fair value, reported as:
Other accrued liabilities	$	—		$	(3.9	)		$	—		$	(3.9	)

Total liabilities measured at fair value	$	—		$	(3.9	)		$	—		$	(3.9	)

________________________________

(1)	Balance includes $41.3 million of restricted investments measured at fair market value related to the Company's D&O Trust and acquisition-related escrows.

(2)	Balance relates to 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)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative instruments	The notional amount of the Company's foreign currency derivatives are summarized as follows (in millions):


		As of
		March 31,		December 31,
		2015		2014
	Cash flow hedges	$	118.5	$	160.7

	Non-designated derivatives	78.4		78

	Total	$	196.9	$	238.7

Goodwill_and_Purchased_Intangi1

Goodwill and Purchased Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	The following table presents goodwill activity during the three months ended March 31, 2015 (in millions):


	Balance as of December 31, 2014	$	2,981.50

	Other	(0.2		)
	Balance as of March 31, 2015	$	2,981.30

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
	As of March 31, 2015
	Intangible assets with finite lives:
	Technologies and patents	$	567.7		$	(477.2	)	$	(49.9	)	$	40.6

	Customer contracts, support agreements, and	78.1			(66.0		)	(2.8		)	9.3
	related relationships
	Other	1.1			(0.5		)	—			0.6

	Total purchased intangible assets	$	646.9		$	(543.7	)	$	(52.7	)	$	50.5


	As of December 31, 2014
	Intangible assets with finite lives:
	Technologies and patents	$	567.7		$	(466.1	)	$	(49.9	)	$	51.7

	Customer contracts, support agreements, and	78.1			(65.2		)	(2.8		)	10.1
	related relationships
	Other	1.1			(0.5		)	—			0.6

	Total purchased intangible assets	$	646.9		$	(531.8	)	$	(52.7	)	$	62.4

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 March 31,
		2015			2014
	Cost of revenues	$	10.8		$	8.2

	Operating expenses:
	Sales and marketing	0.8			1

	General and administrative	0.3			0.3

	Total operating expenses	1.1			1.3

	Total	$	11.9		$	9.5

Estimated future amortization expense of purchased intangible assets with finite lives	As of March 31, 2015, the estimated future amortization expense of purchased intangible assets with finite lives is as follows (in millions):


	Years Ending December 31,	Amount
	Remainder of 2015	$	16.6

	2016	11.6

	2017	7

	2018	5.1

	2019	4.9

	Thereafter	5.3

	Total	$	50.5

Other_Financial_Information_Ta

Other Financial Information (Tables)	3 Months Ended
	Mar. 31, 2015
Other Financial Information [Abstract]
Inventories	Total inventories consisted of the following (in millions):


		As of
		March 31,			December 31,
		2015			2014
	Production materials	$	49.3		$	38.3

	Finished goods	19.5			24.2

	Inventories	$	68.8		$	62.5

Other long-term assets	Other long-term assets consisted of the following (in millions):


		As of
		March 31,			December 31,
		2015			2014
	Privately-held investments	$	93.1		$	89.9

	Licensed software	8.3			8.6

	Federal income tax receivable	28.9			20

	Customer financing receivable	4.5			16.9

	Inventory	9.8			8

	Prepaid costs, deposits, and other	63.7			35.5

	Promissory note in connection with the sale of Junos Pulse(1)	125			125

	Other long-term assets	$	333.3		$	303.9

	_______________________________

	(1)	On October 1, 2014, the Company completed the sale of its Junos Pulse product portfolio. The Company received total consideration of $230.7 million, of which $105.7 million was in cash, net of a $19.3 million working capital adjustment, and $125.0 million was in the form of an 18-month non-contingent interest bearing promissory note issued to the Company.
Warranties	Changes in the Company’s warranty reserve during the three months ended March 31, 2015 were as follows (in millions):


	Balance as of December 31, 2014	$	28.7

	Provisions made during the period	7.3

	Actual costs incurred during the period	(7.1		)
	Balance as of March 31, 2015	$	28.9

Deferred revenue	Details of the Company's deferred revenue, as reported in the Condensed Consolidated Balance Sheets, were as follows (in millions):


		As of
		March 31,			December 31,
		2015			2014
	Deferred product revenue:
	Undelivered product commitments and other product deferrals	$	229.5		$	180.3

	Distributor inventory and other sell-through items	90			103.7

	Deferred gross product revenue	319.5			284

	Deferred cost of product revenue	(66.1		)	(58.4		)
	Deferred product revenue, net	253.4			225.6

	Deferred service revenue	921.3			850.1

	Total	$	1,174.70		$	1,075.70

	Reported as:
	Current	$	855.5		$	780.8

	Long-term	319.2			294.9

	Total	$	1,174.70		$	1,075.70

Other income (expense), net	Other (expense) income, net, consisted of the following (in millions):


		Three Months Ended March 31,
		2015			2014
	Interest income	$	3.8		$	2.1

	Interest expense	(18.5		)	(15.5		)
	Gain on investments	0.6			166.2

	Other	(1.7		)	1.4

	Other (expense) income, net	$	(15.8	)	$	154.2

Restructuring_and_Other_Charge1

Restructuring and Other Charges (Tables)	3 Months Ended
	Mar. 31, 2015
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 charges in the Condensed Consolidated Statements of Operations under the Company's restructuring plans (in millions):


		Three Months Ended March 31,
		2015			2014
	Severance	$	1.5		$	28.3

	Facilities	(0.1		)	0.2

	Contract terminations	—			0.8

	Asset impairment and write-downs	—			93.1

	Total	$	1.4		$	122.4


	Reported as:
	Cost of revenues	$	—		$	8.4

	Restructuring and other charges	1.4			114

	Total	$	1.4		$	122.4

Changes in restructuring liability	The following table provides a summary of changes in the restructuring liability related to the Company's plans during the three months ended March 31, 2015 (in millions):


		December 31,			Charges			Cash			Non-cash			March 31,
		2014						Payments			Settlements and			2015
											Other
	Severance	$	9.4		$	1.5		$	(5.9	)	$	(0.4	)	$	4.6

	Facilities	7.4			(0.1		)	(2.3		)	(0.4		)	4.6

	Contract terminations and other	0.2			—			—			—			0.2

	Total	$	17		$	1.4		$	(8.2	)	$	(0.8	)	$	9.4

Debt_and_Financing_Tables

Debt and Financing (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Instruments [Abstract]
Long-term debt	The following table summarizes the Company's short-term and long-term debt (in millions, except percentages):


		As of March 31, 2015
		Amount			Effective Interest
					Rates
	Senior Notes:
	3.10% fixed-rate notes, due March 2016	$	300		3.25	%

	3.30% fixed-rate notes, due June 2020	300			3.47	%

	4.60% fixed-rate notes, due March 2021	300			4.69	%

	4.50% fixed-rate notes, due March 2024	350			4.63	%

	4.35% fixed-rate notes, due June 2025	300			4.47	%

	5.95% fixed-rate notes, due March 2041	400			6.03	%

	Total senior notes	1,950.00

	Unaccreted discount	(1.4		)
	Total	$	1,948.60


	Reported as:
	Short-term debt	$	299.9

	Long-term debt	1,648.70

	Total	$	1,948.60

Equity_Tables

Equity (Tables)	3 Months Ended
	Mar. 31, 2015
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 three months ended March 31, 2015 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, 2014	8.4		(4.2	)	(18.0	)	(13.8	)

	Other comprehensive loss before reclassifications	(0.8	)	(6.4	)	(11.1	)	(18.3	)
	Amount reclassified from accumulated other	(0.2	)	3.1		—		2.9
	comprehensive income
	Other comprehensive loss, net	(1.0	)	(3.3	)	(11.1	)	(15.4	)
	Balance as of March 31, 2015	7.4		(7.5	)	(29.1	)	(29.2	)

	________________________________

	(1)	The reclassifications out of accumulated other comprehensive income during the three months ended March 31, 2015 for realized gains on available-for-sale securities of $0.2 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 three months ended March 31, 2015 for realized losses on cash flow hedges are included within cost of revenues of $0.9 million, sales and marketing of $2.1 million, and general and administrative of $0.2 million and for realized gains of $0.1 million within research and development for which the hedged transactions relate in the Condensed Consolidated Statements of Operations.

Employee_Benefit_Plans_Tables

Employee Benefit Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of share-based compensation, stock options, activity	The following table summarizes the Company’s stock option activity and related information as of and for the three months ended March 31, 2015 (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, 2014	9.9			$	24.87

	Canceled	(0.1	)		23.52

	Exercised	(0.3	)		14.2

	Expired	(1.7	)		26.32

	Balance as of March 31, 2015	7.8			$	25.05		2.1	$	22.3


	As of March 31, 2015:
	Vested and expected-to-vest options	7.8			$	25.17		2.1	$	21.5

	Exercisable options	7.3			$	26.23		1.8	$	14.7

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 three months ended March 31, 2015 (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, 2014	21.3			$	22.05

	RSUs granted (1)(3)	6.9			22.42

	PSAs granted (2)(3)	0.8			22.44

	RSUs vested	(3.2	)		23.75

	RSAs vested	(0.7	)		21.01

	PSAs vested	(0.2	)		22.6

	RSUs canceled	(0.8	)		22.11

	PSAs canceled	(0.8	)		22.21

	Balance as of March 31, 2015	23.3			$	21.94		1.5	$	525.9

	________________________________

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

	(2)	The number of shares subject to PSAs granted represents the aggregate maximum number of shares that may be issued pursuant to the award over its full term. The aggregate number of shares subject to these PSAs that would be issued if performance goals determined by the Compensation Committee are achieved at target is 0.5 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.

	(3)	The grant date fair value of RSUs and PSAs were reduced by the present value of dividends expected to be paid on the underlying shares of common stock during the requisite and derived service period as these awards are not entitled to receive dividends until vested. On January 27, 2015, the Company declared a cash dividend of $0.10 per share of common stock, or $40.8 million in the aggregate, to stockholders of record on March 3, 2015, which was paid on March 24, 2015.
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 months ended March 31, 2015 and March 31, 2014 were as follows:


		Three Months Ended March 31,
		2015		2014
	ESPP (1):
	Volatility	30%		33%
	Risk-free interest rate	0.10%		0.10%
	Expected life (years)	0.5		0.5
	Dividend yield	1.90%		—
	Weighted-average fair value per share	$5.23		$6.37

	Market-based RSUs (2):
	Volatility	34%		36%
	Risk-free interest rate	1.40%		1.60%
	Dividend yield	0% - 1.8%		0% - 1.5%
	Weighted-average fair value per share	14.97		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 March 31,
		2015				2014
	Cost of revenues - Product	$	1.7			$	1.3

	Cost of revenues - Service	3.4				4

	Research and development	30.7				32.1

	Sales and marketing	5.8				14.6

	General and administrative	4.4				8.8

	Total	$	46			$	60.8

Disclosure of share-based compensation arrangements by share-based payment award	The following table summarizes share-based compensation expense by award type (in millions):


		Three Months Ended March 31,
		2015				2014
	Stock options	$	2.2			$	5.1

	RSUs, RSAs, and PSAs	40.6				51.8

	ESPP	3.2				3.9

	Total	$	46			$	60.8

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 March 31, 2015 (in millions, except years):


		Unrecognized				Weighted Average
		Compensation Cost				Period
						(In Years)
	Stock options	$	7.8			1.2

	RSUs, RSAs, and PSAs	$	325.9			2.1

Segments_Tables

Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Financial information for each segment	The following table presents net revenues by product and service (in millions):


		Three Months Ended March 31,
		2015		2014
	Routing	$	504.8	$	549.8

	Switching	166.5		192

	Security	92.8		134.2

	Total product	764.1		876


	Total service	303.3		294.1

	Total	$	1,067.40	$	1,170.10

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 March 31,
		2015		2014
	Americas:
	United States	$	533.5	$	623.7

	Other	55.5		57.8

	Total Americas	589		681.5

	Europe, Middle East, and Africa	303.8		295.7

	Asia Pacific	174.6		192.9

	Total	$	1,067.40	$	1,170.10

Long-lived Assets by Geographic Areas	The following table presents geographic information for property and equipment, net and purchased intangible assets, net (in millions):


		As of
		March 31,		December 31,
		2015		2014
	United States	$	871	$	871.7

	International	91.7		95

	Property and equipment, net and purchased intangible assets, net	$	962.7	966.7

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of effective income tax rate reconciliation	The effective tax rates for the three months ended March 31, 2015 and March 31, 2014 include the tax expense (benefit) of the following discrete items (in millions):


		Three Months Ended March 31,
		2015			2014
	Tax on equity investments(1)	$	—		$	35.6

	Restructuring	$	(1.3	)	$	(30.8	)
	________________________________
	(1) During the three months ended March 31, 2014, tax on equity investments of $35.6 million is net of a valuation allowance release of $24.7 million

Net_Income_Per_Share_Tables

Net Income Per Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of earnings per share, basic and diluted	The Company computed basic and diluted net income per share attributable to Juniper Networks common stockholders as follows (in millions, except per share amounts):


		Three Months Ended March 31,
		2015		2014
	Numerator:
	Net income	$	80.2	$	110.6

	Denominator:
	Weighted-average shares used to compute basic net income per share	407.1		486.2

	Dilutive effect of employee stock awards	7.1		10.3

	Weighted-average shares used to compute diluted net income per share	414.2		496.5

	Net income per share attributable to Juniper Networks common stockholders:
	Basic	$	0.2	$	0.23

	Diluted	$	0.19	$	0.22


	Anti-dilutive:
	Potential anti-dilutive shares	6.4		25.4

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Details) (USD $)	Mar. 31, 2015	Mar. 31, 2016
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2016
Adjustments for new accounting pronouncements [Line Items]
Expected reduction in debt liabilities	($1,948.60)
Scenario, Forecast [Member] \| Subsequent Event [Member] \| ASU No. 2015-03 [Member]
Adjustments for new accounting pronouncements [Line Items]
Expected reduction in debt issuance cost asset		11
Expected reduction in debt liabilities		$11

Cash_Equivalents_and_Investmen2

Cash Equivalents and Investments - Available-For-Sale and Trading Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Available-for-sale securities, amortized cost	$2,416.80	$2,071.90
Available-for-sale securities, gross unrealized gains	2.2	0.6
Available-for-sale securities, gross unrealized losses	-0.7	-1.7
Available-for-sale securities, estimated fair value	2,418.30	2,070.80
Trading securities:
Trading securities, amortized cost	17.7	16.3
Trading securities, gross unrealized gains	0	0
Trading securities, gross unrealized losses	0	0
Trading securities, estimated fair value	17.7	16.3
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	2,434.50	2,088.20
Total investments, gross unrealized gains	2.2	0.6
Total investments, gross unrealized losses	-0.7	-1.7
Total investments, estimated fair value	2,436	2,087.10
Cash equivalents [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	750.8	576.6
Total investments, gross unrealized gains	0	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	750.8	576.6
Restricted investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	45.3	45.2
Total investments, gross unrealized gains	0.1	0
Total investments, gross unrealized losses	0	0
Total investments, estimated fair value	45.4	45.2
Short-term investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	397.5	332.2
Total investments, gross unrealized gains	0.8	0.2
Total investments, gross unrealized losses	-0.1	-0.2
Total investments, estimated fair value	398.2	332.2
Long-term investments [Member]
Available-for-sale and Trading Securities [Abstract]
Total investments, amortized cost	1,240.90	1,134.20
Total investments, gross unrealized gains	1.3	0.4
Total investments, gross unrealized losses	-0.6	-1.5
Total investments, estimated fair value	1,241.60	1,133.10
Debt Securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	1,634.60	1,471.70
Available-for-sale securities, gross unrealized gains	1.5	0.5
Available-for-sale securities, gross unrealized losses	-0.7	-1.6
Available-for-sale securities, estimated fair value	1,635.40	1,470.60
Asset-backed securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	308.9	269.3
Available-for-sale securities, gross unrealized gains	0.1	0
Available-for-sale securities, gross unrealized losses	-0.2	-0.3
Available-for-sale securities, estimated fair value	308.8	269
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	8.2	10.6
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	8.2	10.6
Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	15.6	20.3
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	15.6	20.3
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	843.2	738.6
Available-for-sale securities, gross unrealized gains	1.1	0.5
Available-for-sale securities, gross unrealized losses	-0.5	-1.1
Available-for-sale securities, estimated fair value	843.8	738
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	34.7	24.6
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	34.7	24.6
Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	190.3	162.2
Available-for-sale securities, gross unrealized gains	0.1	0
Available-for-sale securities, gross unrealized losses	0	-0.1
Available-for-sale securities, estimated fair value	190.4	162.1
US government securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	233.7	246.1
Available-for-sale securities, gross unrealized gains	0.2	0
Available-for-sale securities, gross unrealized losses	0	-0.1
Available-for-sale securities, estimated fair value	233.9	246
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	776.2	594.2
Available-for-sale securities, gross unrealized gains	0	0
Available-for-sale securities, gross unrealized losses	0	0
Available-for-sale securities, estimated fair value	776.2	594.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	4	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	4.1	4
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities, amortized cost	2	2.1
Available-for-sale securities, gross unrealized gains	0.6	0
Available-for-sale securities, gross unrealized losses	0	-0.1
Available-for-sale securities, estimated fair value	$2.60	$2

Cash_Equivalents_and_Investmen3

Cash Equivalents and Investments - Maturities of Fixed Income Investments (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified	Mar. 31, 2015
Schedule of Fixed Income Securities Maturities [Abstract]
Amortized cost due within one year	$393.70
Gross unrealized gains due within one year	0.2
Gross unrealized losses due within one year	-0.1
Estimated fair value due within one year	393.8
Amortized cost due between one and five years	1,240.90
Gross unrealized gains due between one and five years	1.3
Gross unrealized losses due between one and five year	-0.6
Estimated fair value due between one and five year	1,241.60
Total investments, amortized cost	1,634.60
Gross Unrealized Gains	1.5
Gross Unrealized Losses	-0.7
Total investments, estimated fair value	$1,635.40

Cash_Equivalents_and_Investmen4

Cash Equivalents and Investments - Unrealized Loss on Available-for-Sale Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	$750.90	$1,067.20
Unrealized loss, less than 12 months	-0.7	-1.7
Fair value, 12 months or greater	1.7	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	752.6	1,067.20
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.7	-1.7
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	750.9	1,065.20
Unrealized loss, less than 12 months	-0.7	-1.6
Fair value, 12 months or greater	1.7	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	752.6	1,065.20
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.7	-1.6
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	222.4	221.9
Unrealized loss, less than 12 months	-0.2	-0.3
Fair value, 12 months or greater	1.7	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	224.1	221.9
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.2	-0.3
Corporate debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	391.5	515.9
Unrealized loss, less than 12 months	-0.5	-1.1
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	391.5	515.9
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	-0.5	-1.1
Foreign government debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	29.1	24.6
Unrealized loss, less than 12 months	0	0
Fair value, 12 months or greater	0	0
Unrealized loss, 12 months or greater	0	0
Total fair value, available-for-sale investments in continuous unrealized loss position	29.1	24.6
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	0	0
Government-sponsored enterprise obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	60.4	113.8
Unrealized loss, less than 12 months	0	-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	60.4	113.8
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	0	-0.1
US government securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months	47.5	189
Unrealized loss, less than 12 months	0	-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	47.5	189
Total unrealized loss, available-for-sale investments in continuous unrealized loss position	0	-0.1
Publicly-traded equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair value, less than 12 months		2
Unrealized loss, less than 12 months		-0.1
Fair value, 12 months or greater		0
Unrealized loss, 12 months or greater		0
Total fair value, available-for-sale investments in continuous unrealized loss position		2
Total unrealized loss, available-for-sale investments in continuous unrealized loss position		($0.10)

Cash_Equivalents_and_Investmen5

Cash Equivalents, and Investments, Narrative (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	Investment	Mar. 31, 2014	Investment
Cash Equivalents and Investments [Abstract]
Total investments in unrealized loss position	354		437
Available-for-sale securities, other than temporary impairment	$0	$1.60
Available-for-sale securities, gross realized gains	165.5
Privately-held investments	93.1		89.9
Privately held investments at fair value	50.3		47.5
Unrealized gain (loss) on privately-held debt securities	$0	$0

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-for-sale securities:
Available-for-sale securities	$2,418.30	$2,070.80
Trading securities:
Trading securities	17.7	16.3
Fair Value Measurements (Textuals)
Restricted investments	41.2	41.3
Asset-backed Securities [Member]
Available-for-sale securities:
Available-for-sale securities	308.8	269
Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities	8.2	10.6
Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities	15.6	20.3
Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	843.8	738
Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	34.7	24.6
Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities	190.4	162.1
Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities	776.2	594.2
Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities	4.1	4
Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities	2.6	2
US government securities [Member]
Available-for-sale securities:
Available-for-sale securities	233.9	246
Privately-held debt and redeemable preferred stock securities [Member]
Available-for-sale securities:
Available-for-sale securities	1,635.40	1,470.60
Fair Value, Measurements, Recurring [Member]
Derivative assets:
Total assets measured at fair value	2,486.80	2,134.70
Liabilities measured at fair value:
Other accrued liabilities	-6.7	-3.9
Total liabilities measured at fair value	-6.7	-3.9
Cash equivalents	750.8	576.6
Restricted investments	45.4	45.2
Short-term investments	398.2	332.2
Long-term investments	1,241.60	1,133.10
Prepaid expenses and other current assets	0.5	0.1
Other long-term assets	50.3	47.5
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivative assets:
Total assets measured at fair value	1,022.20	862.5
Liabilities measured at fair value:
Other accrued liabilities	0	0
Total liabilities measured at fair value	0	0
Cash equivalents	735	552.9
Restricted investments	45.4	45.2
Short-term investments	65.2	87
Long-term investments	176.6	177.4
Prepaid expenses and other current assets	0	0
Other long-term assets	0	0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative assets:
Total assets measured at fair value	1,414.30	1,224.70
Liabilities measured at fair value:
Other accrued liabilities	-6.7	-3.9
Total liabilities measured at fair value	-6.7	-3.9
Cash equivalents	15.8	23.7
Restricted investments	0	0
Short-term investments	333	245.2
Long-term investments	1,065	955.7
Prepaid expenses and other current assets	0.5	0.1
Other long-term assets	0	0
Fair Value, Measurements, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Derivative assets:
Total assets measured at fair value	50.3	47.5
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	50.3	47.5
Fair Value, Measurements, Recurring [Member] \| Foreign exchange contract [Member]
Derivative assets:
Derivative assets	0.5	0.1
Liabilities measured at fair value:
Derivative liabilities	-6.7	-3.9
Fair Value, Measurements, Recurring [Member] \| Foreign exchange contract [Member] \| Fair Value, Inputs, Level 1 [Member]
Derivative assets:
Derivative assets	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] \| Foreign exchange contract [Member] \| Fair Value, Inputs, Level 2 [Member]
Derivative assets:
Derivative assets	0.5	0.1
Liabilities measured at fair value:
Derivative liabilities	-6.7	-3.9
Fair Value, Measurements, Recurring [Member] \| Foreign exchange contract [Member] \| Fair Value, Inputs, Level 3 [Member]
Derivative assets:
Derivative assets	0	0
Liabilities measured at fair value:
Derivative liabilities	0	0
Fair Value, Measurements, Recurring [Member] \| Asset-backed Securities [Member]
Available-for-sale securities:
Available-for-sale securities	308.8	269
Fair Value, Measurements, Recurring [Member] \| Asset-backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Asset-backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	308.8	269
Fair Value, Measurements, Recurring [Member] \| Asset-backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Certificates of deposit [Member]
Available-for-sale securities:
Available-for-sale securities	8.2	10.6
Fair Value, Measurements, Recurring [Member] \| Certificates of deposit [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Certificates of deposit [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	8.2	10.6
Fair Value, Measurements, Recurring [Member] \| Certificates of deposit [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Commercial paper [Member]
Available-for-sale securities:
Available-for-sale securities	15.6	20.3
Fair Value, Measurements, Recurring [Member] \| Commercial paper [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Commercial paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	15.6	20.3
Fair Value, Measurements, Recurring [Member] \| Commercial paper [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Corporate debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	843.8	738
Fair Value, Measurements, Recurring [Member] \| Corporate debt securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Corporate debt securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	843.8	738
Fair Value, Measurements, Recurring [Member] \| Corporate debt securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Foreign government debt securities [Member]
Available-for-sale securities:
Available-for-sale securities	34.7	24.6
Fair Value, Measurements, Recurring [Member] \| Foreign government debt securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Foreign government debt securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	34.7	24.6
Fair Value, Measurements, Recurring [Member] \| Foreign government debt securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Government-sponsored enterprise obligations [Member]
Available-for-sale securities:
Available-for-sale securities	190.4	162.1
Fair Value, Measurements, Recurring [Member] \| Government-sponsored enterprise obligations [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Government-sponsored enterprise obligations [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	190.4	162.1
Fair Value, Measurements, Recurring [Member] \| Government-sponsored enterprise obligations [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member]
Available-for-sale securities:
Available-for-sale securities	776.2	594.2
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	776.2	594.2
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Money market funds [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Mutual funds [Member]
Available-for-sale securities:
Available-for-sale securities	4.1	4
Trading securities:
Trading securities	17.7	16.3
Fair Value, Measurements, Recurring [Member] \| Mutual funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	4.1	4
Trading securities:
Trading securities	17.7	16.3
Fair Value, Measurements, Recurring [Member] \| Mutual funds [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Trading securities:
Trading securities	0	0
Fair Value, Measurements, Recurring [Member] \| Mutual funds [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Trading securities:
Trading securities	0	0
Fair Value, Measurements, Recurring [Member] \| Publicly-traded equity securities [Member]
Available-for-sale securities:
Available-for-sale securities	2.6	2
Fair Value, Measurements, Recurring [Member] \| Publicly-traded equity securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	2.6	2
Fair Value, Measurements, Recurring [Member] \| Publicly-traded equity securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Publicly-traded equity securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| US government securities [Member]
Available-for-sale securities:
Available-for-sale securities	233.9	246
Fair Value, Measurements, Recurring [Member] \| US government securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	221.6	246
Fair Value, Measurements, Recurring [Member] \| US government securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	12.3	0
Fair Value, Measurements, Recurring [Member] \| US government securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Available-for-sale securities [Member]
Available-for-sale securities:
Available-for-sale securities	2,418.30	2,070.80
Fair Value, Measurements, Recurring [Member] \| Available-for-sale securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	1,004.50	846.2
Fair Value, Measurements, Recurring [Member] \| Available-for-sale securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	1,413.80	1,224.60
Fair Value, Measurements, Recurring [Member] \| Available-for-sale securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0	0
Fair Value, Measurements, Recurring [Member] \| Privately-held debt and redeemable preferred stock securities [Member]
Trading securities:
Privately-held securities	50.3	47.5
Fair Value, Measurements, Recurring [Member] \| Privately-held debt and redeemable preferred stock securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Trading securities:
Privately-held securities	0	0
Fair Value, Measurements, Recurring [Member] \| Privately-held debt and redeemable preferred stock securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Trading securities:
Privately-held securities	0	0
Fair Value, Measurements, Recurring [Member] \| Privately-held debt and redeemable preferred stock securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Trading securities:
Privately-held securities	$50.30	$47.50

Fair_Value_Measurements_Narrat

Fair Value Measurements - Narrative (Details) (USD $)	12 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2015
Security [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Goodwill impairment loss	$850
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Note receivable, fair value	125	125
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Short-term and Long-term debt, fair value	1,395.20	2,026
Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Purchases of privately-held investments		2.8
Cost Method Investment, Privately Held Companies [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost method measured at fair value		$0

Derivative_Instruments_Details

Derivative Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	$196.90	$238.70
Cash flow hedges [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	118.5	160.7
Non-designated derivatives [Member]
Derivatives, Fair Value [Line Items]
Notional amount of foreign currency derivatives	$78.40	$78

Derivative_Instruments_Cash_Fl

Derivative Instruments, Cash Flow Hedges and Offsetting of Derivatives (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
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	($6.10)	$2.70
Foreign exchange contract [Member] \| Cash flow hedging [Member] \| Operating expense [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments, gain (loss) reclassified from accumulated OCI into operating expense, Effective portion	$3	($1)

Derivative_Instruments_NonDesi

Derivative Instruments, Non-Designated Hedges (Details) (Foreign exchange contract [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
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]
Net gain (loss) on non-designated derivative instruments	$2.10	($0.60)

Goodwill_and_Purchased_Intangi2

Goodwill and Purchased Intangible Assets, Goodwill (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Goodwill [Roll Forward]
Balance as of December 31, 2014	$2,981.50
Other	-0.2
Balance as of March 31, 2015	$2,981.30

Goodwill_and_Purchased_Intangi3

Goodwill and Purchased Intangible Assets, Purchased Intangible Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Purchased Intangible Assets [Line Items]
Finite-lived intangible assets, net	$50.50
Total purchased intangible assets, gross	646.9	646.9
Total purchased intangible assets, accumulated amortization	-543.7	-531.8
Total purchased intangible assets, impairments and other charges	-52.7	-52.7
Total purchased intangible assets, net	50.5	62.4
Technologies and patents [Member]
Purchased Intangible Assets [Line Items]
Finite-lived intangible assets, gross	567.7	567.7
Finite-lived intangible assets, accumulated amortization	-477.2	-466.1
Finite-lived intangible assets, impairments and other charges	-49.9	-49.9
Finite-lived intangible assets, net	40.6	51.7
Customer contracts, support agreements, and related relationships [Member]
Purchased Intangible Assets [Line Items]
Finite-lived intangible assets, gross	78.1	78.1
Finite-lived intangible assets, accumulated amortization	-66	-65.2
Finite-lived intangible assets, impairments and other charges	-2.8	-2.8
Finite-lived intangible assets, net	9.3	10.1
Other intangible assets [Member]
Purchased Intangible Assets [Line Items]
Finite-lived intangible assets, gross	1.1	1.1
Finite-lived intangible assets, accumulated amortization	-0.5	-0.5
Finite-lived intangible assets, impairments and other charges	0	0
Finite-lived intangible assets, net	$0.60	$0.60

Goodwill_and_Purchased_Intangi4

Goodwill and Purchased Intangible Assets, Finite Lived Intangible Assets by Class (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$11.90	$9.50
Acceleration of the end of life of certain intangible assets, finite-lived	5.6
Cost of Revenues [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	10.8	8.2
Sales and Marketing Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	0.8	1
General and Administrative Expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	0.3	0.3
Operating expense [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$1.10	$1.30

Goodwill_and_Purchased_Intangi5

Goodwill and Purchased Intangible Assets, Estimated Future Amortization Expense Intangible Assets (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified	Mar. 31, 2015
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Remainder of 2015	$16.60
2016	11.6
2017	7
2018	5.1
2019	4.9
Thereafter	5.3
Finite-lived intangible assets, net	$50.50

Other_Financial_Information_In

Other Financial Information, Inventories, Net (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Restructuring Charges	$1.40
Production materials	49.3		38.3
Finished goods	19.5		24.2
Inventories	68.8		62.5
Restructuring Plan 2014 [Member] \| Inventory Write-down [Member]
Restructuring Charges		$8.40

Other_Financial_Information_Ot

Other Financial Information, Other Long Term Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Oct. 01, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Oct. 01, 2014
Other Financial Information [Line Items]
Privately-held investments	$93.10	$89.90
Licensed software	8.3	8.6
Federal income tax receivable	28.9	20
Customer financing receivable	4.5	16.9
Inventory	9.8	8
Prepaid costs, deposits, and other	63.7	35.5
Promissory note in connection with the sale of Junos Pulse	125	125
Other long-term assets	333.3	303.9
Junos Pulse [Member]
Other Financial Information [Line Items]
Promissory note in connection with the sale of Junos Pulse			125
Consideration			230.7
Cash Consideration			105.7
Working capital adjustment			$19.30

Other_Financial_Information_Wa

Other Financial Information, Warranties (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance as of December 31, 2014	$28.70
Provisions made during the period	7.3
Adjustments related to pre-existing warranties	-7.1
Balance as of March 31, 2015	$28.90

Other_Financial_Information_De

Other Financial Information, Deferred Revenue (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Deferred revenue:
Total deferred revenue	$1,174.70	$1,075.70
Reported as:
Current	855.5	780.8
Long-term	319.2	294.9
Total deferred revenue	1,174.70	1,075.70
Sales Revenue, Product, Net [Member]
Deferred revenue:
Undelivered product commitments and other product deferrals	229.5	180.3
Distributor inventory and other sell-through items	90	103.7
Deferred gross product revenue	319.5	284
Deferred cost of product revenue	-66.1	-58.4
Total deferred revenue	253.4	225.6
Reported as:
Total deferred revenue	253.4	225.6
Sales Revenue, Service, Net [Member]
Deferred revenue:
Total deferred revenue	921.3	850.1
Reported as:
Total deferred revenue	$921.30	$850.10

Other_Financial_Information_Ot1

Other Financial Information, Other Income (Expense), Net (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Financial Information [Abstract]
Interest income	$3.80	$2.10
Interest expense	-18.5	-15.5
Gain on investments	0.6	166.2
Other	-1.7	1.4
Other (expense) income, net	-15.8	154.2
Publicly-traded equity and privately-held investments, net realized gain		$163

Restructuring_and_Other_Charge2

Restructuring and Other Charges (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Restructuring Reserve [Line Items]
Restructuring and other charges	$1.40	$122.40
Restructuring reserve	9.4
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of period	17
Restructuring charges	1.4
Cash Payments	-8.2
Non-cash Settlements and Other	-0.8
Restructuring reserve, end of period	9.4
Cost of Revenues [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	0	8.4
Operating expense [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	1.4	114
Severance [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	1.5	28.3
Restructuring reserve	4.6
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of period	9.4
Restructuring charges	1.5
Cash Payments	-5.9
Non-cash Settlements and Other	-0.4
Restructuring reserve, end of period	4.6
Severance [Member] \| Restructuring Plan 2014 [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	1.5	28
Facilities [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	-0.1	0.2
Restructuring reserve	4.6
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of period	7.4
Restructuring charges	-0.1
Cash Payments	-2.3
Non-cash Settlements and Other	-0.4
Restructuring reserve, end of period	4.6
Facilities [Member] \| Restructuring Plan 2014 [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	0.1
Contract terminations [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	0	0.8
Restructuring reserve	0.2
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning of period	0.2
Restructuring charges	0
Cash Payments	0
Non-cash Settlements and Other	0
Restructuring reserve, end of period	0.2
Contract terminations [Member] \| Restructuring Plan 2014 [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges		0.8
Asset impairment and write-downs [Member]
Restructuring Reserve [Line Items]
Restructuring and other charges	0	93.1
Impairment charges related to licensed software [Member] \| Restructuring Plan 2014 [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges		84.7
Inventory Write-down [Member] \| Restructuring Plan 2014 [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges		8.4
Employee Severance and Contract Terminations [Member]
Restructuring Reserve [Line Items]
Restructuring reserve	4.8
Restructuring Reserve [Roll Forward]
Restructuring reserve, end of period	$4.80

Debt_and_Financing_Details

Debt and Financing (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Mar. 31, 2011
Long-Term Debt [Line Items]
Long-term debt, gross	$1,950
Unaccreted discount	-1.4
Long-term Debt	1,948.60
Short-term debt	299.9		0
Long-term debt	1,648.70		1,349
Redemption percent due to change in control	101.00%
Financing Arrangements [Abstract]
Sale of receivable	47.1	133
Proceeds from sale and collection of receivables	60	192.3
Receivables from sale of receivables	15.1	28
Maximum term for guarantees related to third-party financing arrangements	4 years
Cash received from financing provider that has not been recognized as revenue	13.3		67.5
Financing guarantee with recourse [Member]
Financing Arrangements [Abstract]
Guarantor obligations, current carrying value	11.1
Minimum [Member]
Financing Arrangements [Abstract]
Number of days due from receivable	30 days
Maximum [Member]
Financing Arrangements [Abstract]
Number of days due from receivable	90 days
Fixed rate note due 2016 [Member]
Long-Term Debt [Line Items]
Short-term debt, gross	300			300
Effective interest rate	3.25%
Long-term debt, stated interest rate	3.10%			3.10%
Fixed rate note due 2020 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	300
Effective interest rate	3.47%
Long-term debt, stated interest rate	3.30%
Redemption period	1 month
Fixed rate note due 2020 [Member] \| One Month Prior to Maturity [Member]
Long-Term Debt [Line Items]
Redemption price	100.00%
Fixed rate note due 2020 [Member] \| Three Months Prior to Maturity [Member] \| Treasury Rate [Member]
Long-Term Debt [Line Items]
Redemption discount rate, basis spread on variable rate	0.30%
Fixed rate note due 2020 [Member] \| On or After May 15, 2020 [Member]
Long-Term Debt [Line Items]
Redemption price	100.00%
Fixed rate note due 2021 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	300			300
Effective interest rate	4.69%
Long-term debt, stated interest rate	4.60%			4.60%
Fixed rate note due 2024 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	350	350
Effective interest rate	4.63%
Long-term debt, stated interest rate	4.50%	4.50%
Fixed rate note due 2025 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	300
Effective interest rate	4.47%
Long-term debt, stated interest rate	4.35%
Redemption period	3 months
Fixed rate note due 2025 [Member] \| One Month Prior to Maturity [Member] \| Treasury Rate [Member]
Long-Term Debt [Line Items]
Redemption discount rate, basis spread on variable rate	0.38%
Fixed rate note due 2025 [Member] \| Three Months Prior to Maturity [Member]
Long-Term Debt [Line Items]
Redemption price	100.00%
Fixed rate note due 2025 [Member] \| On or After March 15, 2025 [Member]
Long-Term Debt [Line Items]
Redemption price	100.00%
Fixed rate note due 2041 [Member]
Long-Term Debt [Line Items]
Long-term debt, gross	$400			$400
Effective interest rate	6.03%
Long-term debt, stated interest rate	5.95%			5.95%
Other Fixed Rate Notes [Member]
Long-Term Debt [Line Items]
Redemption price	100.00%

Debt_and_Financing_Revolving_C

Debt and Financing Revolving Credit Facility (Details) (Revolving Credit Facility [Member], USD $)	0 Months Ended
	Jun. 27, 2014
Line of Credit Facility [Line Items]
Revolving credit facility limit	500,000,000
Revolving credit facility, additional borrowing capacity	200,000,000
Base Rate [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.00%
Base Rate [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
Eurodollar [Member] \| Minimum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.90%
Eurodollar [Member] \| Maximum [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.50%
Federal Funds Rate [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
ICE Benchmark Administration Settlement Rate [Member]
Line of Credit Facility [Line Items]
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		3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 24, 2015	Jan. 27, 2015	Mar. 31, 2015	Mar. 31, 2014
Stockholders' Equity Note [Abstract]
Cash dividends declared per common stock (in dollar per share)		$0.10	$0.10	$0
Common stock dividends paid	$40.80

Equity_Stock_Repurchase_Activi

Equity, Stock Repurchase Activities (Details) (USD $)	0 Months Ended	3 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Jul. 23, 2014	Mar. 31, 2015	Mar. 31, 2014	Oct. 31, 2014	Feb. 28, 2014
			agreement
			institution
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount				$3,400,000,000	$2,100,000,000
Stock repurchased and retired		17.4
Common stock repurchased under stock repurchase program average purchase price (in dollars per share)		$23.05
Common stock repurchased and retired under stock repurchase program, value		400,000,000	900,000,000
Number of accelerated share repurchase agreements			2
Number of financial institutions for ASR			2
Accelerated share repurchases, aggregate payments made during period			1,200,000,000
Shares repurchased under ASR	16
Accelerated share repurchases, shares repurchased	49.3
Accelerated share repurchases, weighted average repurchase price (in USD per share)	$24.35
Intended stock repurchases		600,000,000
2014 Stock Repurchase Program [Member]
Accelerated Share Repurchases [Line Items]
Stock repurchase program, authorized amount			1,200,000,000
Additional amount authorized under Stock Repurchase Plan				1,300,000,000
Stock repurchased and retired			33.3
Accelerated share repurchases, remaining amount recorded in equity	300,000,000
Stock repurchase program, remaining authorized repurchase amount		$775,000,000

Equity_Components_of_Accumulat

Equity, Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	($13.80)
Other comprehensive loss before reclassifications	-18.3
Amount reclassified from accumulated other comprehensive income	2.9
Other comprehensive loss, net of tax	-15.4	-62.7
Balance as of March 31, 2015	-29.2
Cost of revenues	410.1	450
Sales and marketing	220.2	273.4
General and administrative	55.2	74.9
Research and development	248.7	264
Unrealized Gains (Losses) on Available-for- Sale Securities
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	8.4
Other comprehensive loss before reclassifications	-0.8
Amount reclassified from accumulated other comprehensive income	-0.2
Other comprehensive loss, net of tax	-1
Balance as of March 31, 2015	7.4
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	-4.2
Other comprehensive loss before reclassifications	-6.4
Amount reclassified from accumulated other comprehensive income	3.1
Other comprehensive loss, net of tax	-3.3
Balance as of March 31, 2015	-7.5
Cost of revenues	0.9
Sales and marketing	2.1
General and administrative	0.2
Research and development	-0.1
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive (Loss) Income, Net of Tax [Roll Forward]
Balance as of December 31, 2014	-18
Other comprehensive loss before reclassifications	-11.1
Amount reclassified from accumulated other comprehensive income	0
Other comprehensive loss, net of tax	-11.1
Balance as of March 31, 2015	($29.10)

Employee_Benefit_Plans_Details

Employee Benefit Plans (Details) (USD $)	3 Months Ended
Employee Benefit Plans (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Share-Based Compensation Plans
Common stock, shares, issued	403,800,000	416,200,000
Outstanding stock options, restricted stock units, and restricted stock awards from awards assumed	3,300,000
Number of Shares
Balance as of December 31, 2014 (in shares)	9,900,000
Canceled (in shares)	-100,000
Exercised (in shares)	-300,000
Expired (in shares)	-1,700,000
Balance as of March 31, 2015 (in shares)	7,800,000
Weighted Average Exercise Price per Share
Balance as of December 31, 2014 (in dollars per share)	$24.87
Canceled (in dollars per share)	$23.52
Exercised (in dollars per share)	$14.20
Expired (in dollars per share)	$26.32
Balance as of March 31, 2015 (in dollars per share)	$25.05
Weighted average remaining contractual term at March 31, 2015	2 years 1 month 6 days
Aggregate intrinsic value at March 31, 2015	$22,300,000
Vested or expected-to-vest options at March 31, 2015 (in shares)	7,800,000
Vested or expected-to-vest options, weighted average exercise price at March 31, 2015 (in dollars per share)	$25.17
Vested and expected-to-vest options, weighted average remaining contractual term at March 31, 2015	2 years 1 month 6 days
Vested or expected-to-vest options, aggregate intrinsic value at March 31, 2015	21,500,000
Exercisable options at March 31, 2015 (in shares)	7,300,000
Exercisable options, weighted average exercise price at March 31, 2015 (in dollars per share)	$26.23
Exercisable options, weighted average remaining contractual term at March 31, 2015	1 year 9 months 18 days
Exercisable options, aggregate intrinsic value at March 31, 2015	14,700,000
Share price (in dollars per share)	$22.58
Pre-tax intrinsic value of options exercised	3,300,000
Equity incentive plan 2006
Share-Based Compensation Plans
Number of shares in authorized	149,500,000
Number of shares available for future issuance	36,200,000
Plan 1996 and 2000 [Member]
Share-Based Compensation Plans
Maximum additional shares expire unexercised, under 1996 and 2000 plan	75,000,000
Equity Incentive Plan 1996, 2000, and 2006 [Member]
Share-Based Compensation Plans
Number of shares outstanding	27,800,000
Employee stock purchase plan 2008 [Member]
Share-Based Compensation Plans
Number of shares available for future issuance	1,900,000
Common stock, capital shares reserved for future issuance	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%
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	17,100,000

Employee_Benefit_Plans_Share_B

Employee Benefit Plans, Share Based Compensation, Equity Instruments Other Than Options (Details) (USD $)	0 Months Ended	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 24, 2015	Mar. 31, 2015	Mar. 31, 2014
Weighted Average Grant-Date Fair Value per Share
Common stock, dividends paid per share (in dollar per share)	$0.10
Employee Stock Purchase Plan
Common stock dividends paid	$40.80
Employee stock purchase plan 2008 [Member]
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
Average price of common stock, per share		$19.32	$18.67
RSUs, RSAs, and PSAs [Member]
Number of Shares
Balance as of December 31, 2014 (in shares)		21,300,000
Balance as of March 31, 2015 (in shares)		23,300,000
Weighted Average Grant-Date Fair Value per Share
Balance as of December 31, 2014 (in dollars per share)		$22.05
Balance as of March 31, 2015 (in dollars per share)		$21.94
Weighted Average Remaining Contractual Term (In Years)		1 year 6 months
Aggregate Intrinsic Value		$525.90
Restricted stock units (RSUs)
Number of Shares
Granted (in shares)		6,900,000
Vested (in shares)		-3,200,000
Canceled (in shares)		-800,000
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$22.42
Vested (in dollars per share)		$23.75
Canceled (in dollars per share)		$22.11
Performance shares (PSAs)
Number of Shares
Granted (in shares)		800,000
Vested (in shares)		-200,000
Canceled (in shares)		-800,000
Weighted Average Grant-Date Fair Value per Share
Granted (in dollars per share)		$22.44
Vested (in dollars per share)		$22.60
Canceled (in dollars per share)		$22.21
Aggregate number of shares subject to PSAs granted		500,000
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
Restricted stock awards (RSAs)
Number of Shares
Vested (in shares)		-700,000
Weighted Average Grant-Date Fair Value per Share
Vested (in dollars per share)		$21.01

Employee_Benefit_Plans_Assumpt

Employee Benefit Plans, Assumptions and Resulting Estimates of Fair Value (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
ESPP [Member]
Estimates of Fair Value
Volatility	30.00%	33.00%
Risk-free interest rate	0.10%	0.10%
Expected life (years)	6 months	6 months
Dividend yield	1.90%	0.00%
Weighted-average fair value per share (in dollars per share)	$5.23	$6.37
Market-based RSUs [Member]
Estimates of Fair Value
Volatility	34.00%	36.00%
Risk-free interest rate	1.40%	1.60%
Weighted-average fair value per share (in dollars per share)	$14.97	$18.28
Market-based RSUs [Member] \| Minimum [Member]
Estimates of Fair Value
Dividend yield	0.00%	0.00%
Market-based RSUs [Member] \| Maximum [Member]
Estimates of Fair Value
Dividend yield	1.80%	1.50%

Employee_Benefit_Plans_Share_B1

Employee Benefit Plans, Share Based Compensation by Cost and Expense Categories (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$46	$60.80
Stock Options [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	2.2	5.1
RSUs, RSAs, and PSAs [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	40.6	51.8
ESPP [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	3.2	3.9
Cost of Revenues, Product [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	1.7	1.3
Cost of Revenues, Service [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	3.4	4
Research and Development [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	30.7	32.1
Sales and Marketing [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	5.8	14.6
General and Administrative [Member]
Stock Based Compensation Expense Recorded in Cost and Expense Categories
Share-based compensation expense	$4.40	$8.80

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	Mar. 31, 2015
Stock Options [Member]
Unrecognized Compensation Cost [Abstract]
Unrecognized Compensation Cost	$7.80
Weighted Average Period (In Years)	1 year 2 months 12 days
RSUs, RSAs, and PSAs [Member]
Unrecognized Compensation Cost [Abstract]
Unrecognized Compensation Cost	$325.90
Weighted Average Period (In Years)	2 years 1 month 6 days

Segments_Details

Segments (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Total net revenues	$1,067.40	$1,170.10
Routing [Member]
Segment Reporting Information [Line Items]
Total net revenues	504.8	549.8
Switching [Member]
Segment Reporting Information [Line Items]
Total net revenues	166.5	192
Security [Member]
Segment Reporting Information [Line Items]
Total net revenues	92.8	134.2
Total product [Member]
Segment Reporting Information [Line Items]
Total net revenues	764.1	876
Total service [Member]
Segment Reporting Information [Line Items]
Total net revenues	$303.30	$294.10

Segments_Geographical_Details

Segments, Geographical (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Net Revenues by Geographic Region [Line Items]
Total net revenues	$1,067.40	$1,170.10
Property and equipment, net and purchased intangible assets, net	962.7		966.7
United States [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues	533.5	623.7
Property and equipment, net and purchased intangible assets, net	871		871.7
Other [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues	55.5	57.8
Americas [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues	589	681.5
EMEA [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues	303.8	295.7
Asia Pacific [Member]
Net Revenues by Geographic Region [Line Items]
Total net revenues	174.6	192.9
International [Member]
Net Revenues by Geographic Region [Line Items]
Property and equipment, net and purchased intangible assets, net	$91.70		$95

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2009
Income Tax Contingency [Line Items]
Effective income tax rate reconciliation, at federal statutory income tax rate	30.90%	25.30%
Federal statutory rate	35.00%	35.00%
Tax on equity investments	$0	$35.60
Restructuring	-1.3	-30.8
Valuation allowance release related to gain on sale of equity investments	24.7
Unrecognized tax benefits	201.3
Unrecognized tax benefits that would impact effective tax rate	167.3
Foreign country
Income Tax Contingency [Line Items]
Interest and penalties recorded			4.6
Maximum [Member]
Income Tax Contingency [Line Items]
Greater than remote likelihood decrease in gross unrecognized tax benefits within next 12 months	$3.10

Net_Income_Per_Share_Details

Net Income Per Share (Details) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Numerator
Net income	$80.20	$110.60
Denominator
Weighted-average shares used to compute basic net income per share	407.1	486.2
Dilutive effect of employee stock awards	7.1	10.3
Weighted-average shares used to compute diluted net income per share	414.2	496.5
Net income per share:
Basic, in dollars per share	$0.20	$0.23
Diluted, in dollars per share	$0.19	$0.22
Net Income per Share Textuals
Potential anti-dilutive shares	6.4	25.4

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Mar. 31, 2011
Summarization of principal contractual obligations
Future minimum payments under the non-cancelable operating leases	$132
Rent expense	11.5	13
Total purchase commitments	388.6
Accrual for estimated carrying charges or obsolete materials charges	23
Short-term debt	299.9		0
Long-term debt, carrying value	1,648.70		1,349
Long-term debt, gross	1,950
Indemnity-related and service-related escrows	46
Campus build out commitments	3.5
Other contractual obligations	29.6
Long-term income taxes payable	178.9		177.5
Fixed rate note due 2016 [Member]
Summarization of principal contractual obligations
Short-term debt, gross	300			300
Long-term debt, stated interest rate	3.10%			3.10%
Fixed rate note due 2020 [Member]
Summarization of principal contractual obligations
Long-term debt, gross	300
Long-term debt, stated interest rate	3.30%
Fixed rate note due 2021 [Member]
Summarization of principal contractual obligations
Long-term debt, gross	300			300
Long-term debt, stated interest rate	4.60%			4.60%
Fixed rate note due 2024 [Member]
Summarization of principal contractual obligations
Long-term debt, gross	350	350
Long-term debt, stated interest rate	4.50%	4.50%
Fixed rate note due 2025 [Member]
Summarization of principal contractual obligations
Long-term debt, gross	300
Long-term debt, stated interest rate	4.35%
Fixed rate note due 2041 [Member]
Summarization of principal contractual obligations
Long-term debt, gross	400			400
Long-term debt, stated interest rate	5.95%			5.95%
Purchase Commitment [Member]
Summarization of principal contractual obligations
Loss contingency accrual	$8.80

Commitments_and_Contingencies_1

Commitments and Contingencies, Guarantees (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Financing guarantees, bank guarantees, and standby letters of credit [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$16.30	$26.20
Financing guarantee with recourse [Member]
Guarantor Obligations [Line Items]
Guarantor obligations, current carrying value	$11.10

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	0 Months Ended	3 Months Ended		0 Months Ended	1 Months Ended
Share data in Millions, except Per Share data, unless otherwise specified	Jan. 27, 2015	Mar. 31, 2015	Mar. 31, 2014	Apr. 23, 2015	8-May-15
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollar per share)	$0.10	$0.10	$0
Common stock repurchased under stock repurchase program average purchase price (in dollars per share)		$23.05
Stock repurchased and retired		17.4
Subsequent Event [Member]
Subsequent Event [Line Items]
Cash dividends declared per common stock (in dollar per share)				$0.10
2014 Stock Repurchase Program [Member]
Subsequent Event [Line Items]
Stock repurchased and retired			33.3
Stock repurchase program, remaining authorized repurchase amount		$775,000,000
2014 Stock Repurchase Program [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Stock repurchased during period					12.8
Stock repurchased during period, value					315,000,000
Common stock repurchased under stock repurchase program average purchase price (in dollars per share)					$24.54
Stock repurchased and retired					11.7
Stock repurchase program, remaining authorized repurchase amount					$460,000,000