CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands		Total		Common Stock		Additional Paid-In Capital		Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Retained Earnings (Accumulated Deficit)
Balance at Dec. 31, 2014		$ 588,150		$ 0		$ 627,742		$ 0	$ (5,609)	$ (33,983)
Balance (in shares) at Dec. 31, 2014				72,920,582
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options		12,255				12,255
Issuance of common stock upon exercises of employee stock options (in shares)				935,143
Issuance of common stock upon release of restricted stock units (RSUs)		0
Issuance of common stock upon release of restricted stock units (RSUs) (in shares)				422,981
Issuance of common stock for employee stock purchase plan		8,911				8,911
Issuance of common stock for employee stock purchase plan (in shares)				312,697
Stock-based compensation (inclusive of capitalized stock-based compensation)		63,887				63,887
Repurchase of common stock from employees		(482)				(482)
Repurchase of common stock from employees (in shares)				(12,022)
Issuance of common stock in connection with acquisition of SeatMe, Inc.		0
Issuance of common stock in connection with acquisition of SeatMe, Inc. (in shares)				577
Issuance of common stock in connection with acquisition of Eat24Hours.com, Inc.		59,158				59,158
Issuance of common stock in connection with acquisition of Eat24Hours.com, Inc., (in shares)				1,402,844
Excess tax benefit from share-based award activity		2,551				2,551
Foreign currency translation adjustment		(7,910)							(7,910)
Net income (loss)		(32,900)								(32,900)
Balance at Dec. 31, 2015		693,620		$ 0		774,022		0	(13,519)	(66,883)
Balance (in shares) at Dec. 31, 2015				75,982,802
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment upon adoption of ASU 2016-09		169	[1]			(1,163)	[2]			1,332	[1]
Issuance of common stock upon exercises of employee stock options		20,599				20,599
Issuance of common stock upon exercises of employee stock options (in shares)				1,290,836
Issuance of common stock upon release of restricted stock units (RSUs)		0
Issuance of common stock upon release of restricted stock units (RSUs) (in shares)				1,814,138
Issuance of common stock for employee stock purchase plan		8,923				8,923
Issuance of common stock for employee stock purchase plan (in shares)				342,057
Stock-based compensation (inclusive of capitalized stock-based compensation)		90,602				90,602
Foreign currency translation adjustment		(2,057)							(2,057)
Net income (loss)		(4,670)								(4,670)
Balance at Dec. 31, 2016		$ 807,186		$ 0		892,983		0	(15,576)	(70,221)
Balance (in shares) at Dec. 31, 2016		79,429,833		79,429,833
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options		$ 29,997				29,997
Issuance of common stock upon exercises of employee stock options (in shares)		1,519,771		1,519,771
Issuance of common stock upon release of restricted stock units (RSUs)		$ 0
Issuance of common stock upon release of restricted stock units (RSUs) (in shares)				2,702,838
Issuance of common stock for employee stock purchase plan		10,920				10,920
Issuance of common stock for employee stock purchase plan (in shares)				373,580
Stock-based compensation (inclusive of capitalized stock-based compensation)		106,639				106,639
Repurchase of common stock from employees		$ (12,600)
Repurchase of common stock from employees (in shares)		(302,206)
Shares withheld related to net share settlement of equity awards		$ (2,522)				(2,522)
Repurchase of common stock	[3]	$ (12,602)						(46)		(12,556)
Repurchase of common stock (in shares)		(301,106)		(301,106)	[3]
Foreign currency translation adjustment		$ 7,620							7,620
Foreign currency translation adjustment due to dissolved subsidiaries		(488)							(488)
Net income (loss)		152,858								152,858
Balance at Dec. 31, 2017		$ 1,099,608		$ 0		$ 1,038,017		$ (46)	$ (8,444)	$ 70,081
Balance (in shares) at Dec. 31, 2017		83,724,916		83,724,916

[1] Adopted on a modified retrospective basis; refer to significant accounting policies in Note 2 for details regarding this adoption.

[2] The structure of the Company’s common stock changed in the year ended December 31, 2016. Refer to Note 13 for details.

[3] 1,100 shares were excluded from the share total that were repurchased but not yet retired, and held as treasury stock as of December 31, 2017.