Date when the acquirer obtains control of the acquiree, in CCYY-MM-DD format.

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This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Number of shares of stock issued during the period pursuant to acquisitions.

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Acquisitions - Additional Information (Detail) (USD $)	9 Months Ended		0 Months Ended	3 Months Ended	9 Months Ended	0 Months Ended
Acquisitions - Additional Information (Detail) (USD $)	Sep. 30, 2013	Sep. 30, 2014	Aug. 08, 2013 GrubHub Holdings Inc	Sep. 30, 2013 GrubHub Holdings Inc General and administrative expenses	Sep. 30, 2013 GrubHub Holdings Inc General and administrative expenses	Aug. 08, 2013 GrubHub Holdings Inc Non-vested stock options	Aug. 08, 2013 GrubHub Holdings Inc Common Stock	Aug. 08, 2013 GrubHub Holdings Inc Preferred Stock
Business Acquisition [Line Items]
Business acquisitions, share issued							23,318,580	8,098,430
Acquisition date			Aug. 08, 2013
Fair value of shares issued	$ 421,485,000		$ 421,485,000			$ 11,000,000
Unrecognized compensation expense		20,000,000				12,500,000
Direct and indirect expense incurred related to merger				$ 1,300,000	$ 4,700,000