Acquisitions - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	9 Months Ended		1 Months Ended	9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	May 31, 2014 Gnip Inc	Sep. 30, 2014 Gnip Inc Developed Technology Rights	May 31, 2014 Gnip Inc Developed Technology Rights	Sep. 30, 2014 Gnip Inc Customer Relationships	May 31, 2014 Gnip Inc Customer Relationships	Sep. 30, 2014 Series of Individually Immaterial Business Acquisitions Acquisition	Sep. 30, 2014 Series of Individually Immaterial Business Acquisitions Developed Technology Rights	Sep. 30, 2014 Series of Individually Immaterial Business Acquisitions Developed Technology Rights Minimum	Sep. 30, 2014 Series of Individually Immaterial Business Acquisitions Developed Technology Rights Maximum	Sep. 30, 2014 Series of Individually Immaterial Business Acquisitions Customer Relationships	Sep. 30, 2014 All Acquisitions Employee Stock Option
Business Acquisition [Line Items]
Business acquisition, purchase price cash consideration			$ 107,300,000					$ 66,900,000
Business acquisition, common stock issued including shares of restricted stock			0.6
Business acquisition, common shares issuable in respect of assumed equity awards held by individuals			0.4
Business Combination, Consideration Transferred			134,100,000					188,100,000
Acquisition purchase price allocated to finite lived intangible assets					23,200,000		9,300,000		28,100,000			1,600,000
Acquisition purchase price allocated to liability			5,800,000
Acquisition purchase price allocated to deferred tax liability			6,400,000					3,200,000
Goodwill	622,638,000	363,477,000	104,700,000					155,100,000
Acquisition purchase price allocated to assets			9,100,000					6,500,000
Estimated useful life of intangible assets				60 months		60 months				12 months	48 months
Number of businesses acquired								8
Business acquisition, common stock issued								121,200,000
Fair value of contingent payment	97,700,000
Equity compensation service period	4 years												48 months
Unrecognized share-based compensation expense													$ 16,900,000