CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance (in shares) at Dec. 31, 2018			81,996,839
Balance at beginning at Dec. 31, 2018	$ 1,075,518		$ 0	$ 1,139,462	$ 0	$ (11,021)	$ (52,923)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)			173,956
Issuance of common stock upon exercises of employee stock options	3,661			3,661
Issuance of common stock upon vesting of RSUs (in shares)			982,911
Issuance of common stock for employee stock purchase plan (in shares)			288,529
Issuance of common stock for employee stock purchase plan	7,537			7,537
Stock-based compensation (inclusive of capitalized stock-based compensation)	66,670			66,670
Shares withheld related to net share settlement of equity awards	(22,844)			(22,844)
Repurchases of common stock	(397,613)				(397,613)
Retirement of common stock (in shares)			(11,510,446)
Retirement of common stock					391,661		(391,661)
Foreign currency adjustments	(142)					(142)
Net (loss) income	13,668						13,668
Balance (in shares) at Jun. 30, 2019			71,931,789
Balance at end at Jun. 30, 2019	746,455		$ 0	1,194,486	(5,952)	(11,163)	(430,916)
Balance (in shares) at Mar. 31, 2019			79,689,829
Balance at beginning at Mar. 31, 2019	994,838		$ 0	1,160,254	0	(11,732)	(153,684)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)			123,174
Issuance of common stock upon exercises of employee stock options	2,516			2,516
Issuance of common stock upon vesting of RSUs (in shares)			493,477
Issuance of common stock for employee stock purchase plan (in shares)			288,529
Issuance of common stock for employee stock purchase plan	7,537			7,537
Stock-based compensation (inclusive of capitalized stock-based compensation)	34,196			34,196
Shares withheld related to net share settlement of equity awards	(10,017)			(10,017)
Repurchases of common stock	(295,487)				(295,487)
Retirement of common stock (in shares)			(8,663,220)
Retirement of common stock					289,535		(289,535)
Foreign currency adjustments	569					569
Net (loss) income	12,303						12,303
Balance (in shares) at Jun. 30, 2019			71,931,789
Balance at end at Jun. 30, 2019	$ 746,455		$ 0	1,194,486	(5,952)	(11,163)	(430,916)
Balance (in shares) at Dec. 31, 2019	71,185,468		71,185,468
Balance at beginning at Dec. 31, 2019	$ 754,991	$ (34)	$ 0	1,259,803	0	(11,759)	(493,053)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)	222,357		222,357
Issuance of common stock upon exercises of employee stock options	$ 2,794			2,794
Issuance of common stock upon vesting of RSUs (in shares)			1,279,707
Issuance of common stock for employee stock purchase plan (in shares)			433,697
Issuance of common stock for employee stock purchase plan	8,014			8,014
Stock-based compensation (inclusive of capitalized stock-based compensation)	66,886			66,886
Shares withheld related to net share settlement of equity awards	(11,752)			(11,752)
Foreign currency adjustments	(86)					(86)
Net (loss) income	$ (39,493)						(39,493)
Balance (in shares) at Jun. 30, 2020	73,121,229		73,121,229
Balance at end at Jun. 30, 2020	$ 781,320		$ 0	1,325,745	0	(11,845)	(532,580)
Balance (in shares) at Mar. 31, 2020			71,887,846
Balance at beginning at Mar. 31, 2020	762,432		$ 0	1,283,885	0	(12,863)	(508,590)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercises of employee stock options (in shares)			21,510
Issuance of common stock upon exercises of employee stock options	209			209
Issuance of common stock upon vesting of RSUs (in shares)			778,176
Issuance of common stock for employee stock purchase plan (in shares)			433,697
Issuance of common stock for employee stock purchase plan	8,014			8,014
Stock-based compensation (inclusive of capitalized stock-based compensation)	33,637			33,637
Foreign currency adjustments	1,018					1,018
Net (loss) income	$ (23,990)						(23,990)
Balance (in shares) at Jun. 30, 2020	73,121,229		73,121,229
Balance at end at Jun. 30, 2020	$ 781,320		$ 0	$ 1,325,745	$ 0	$ (11,845)	$ (532,580)