Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2016	$ 258,413	$ 36	$ 266,794	$ (156)	$ (8,261)
Balance (in shares) at Dec. 31, 2016		35,841,001
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,440				40,440
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(418)			(418)
Change in unrealized loss on investments	(418)
Issuance of common stock upon exercise of stock options	$ 31,327	$ 3	31,324
Issuance of common stock upon exercise of stock options (shares)	2,997,095	2,997,095
Issuance of common stock upon vesting of restricted stock units (in shares)		368,367
Taxes from release of the restricted share units	$ (20,924)		(20,924)
Taxes related to net share settlement of equity awards, shares		(608,346)
Stock-based compensation	26,961		26,961
Balance at Dec. 31, 2017	343,544	$ 39	304,155	(574)	39,924
Balance (in shares) at Dec. 31, 2017		38,598,117
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	57,304
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(12)
Change in unrealized loss on investments	28
Issuance of common stock upon exercise of stock options	$ 24,053	$ 1	$ 24,052
Issuance of common stock upon exercise of stock options (shares)	1,183,235	1,183,235
Stock Repurchased During Period, Shares		1,088,899	13,064,000
Treasury Stock, Value, Acquired, Cost Method		$ 1
Issuance of common stock upon vesting of restricted stock units (in shares)		525,375
Taxes from release of the restricted share units	$ (14,879)		$ (14,879)
Taxes related to net share settlement of equity awards, shares		(202,794)
Stock-based compensation	30,308		30,308
Balance at Dec. 31, 2018	357,989	$ 39	330,572	(586)	27,964
Balance (in shares) at Dec. 31, 2018		39,015,034
Accumulated deficit	27,964
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	69,336				69,336
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1,748			1,748
Change in unrealized loss on investments	1,367
Issuance of common stock upon exercise of stock options	$ 24,831	$ 1	24,830
Issuance of common stock upon exercise of stock options (shares)	901,290	901,290
Stock Repurchased During Period, Shares		(1,026,455)
Treasury Stock, Value, Acquired, Cost Method	$ (86,424)	$ (1)	(12,317)		(74,106)
Issuance of common stock upon vesting of restricted stock units (in shares)		438,892
Taxes from release of the restricted share units	(15,743)		(15,743)
Taxes related to net share settlement of equity awards, shares		(182,489)
Stock-based compensation	35,066		35,066
Balance at Dec. 31, 2019	386,803	$ 39	$ 362,408	$ 1,162	$ 23,194
Balance (in shares) at Dec. 31, 2019		39,146,272
Accumulated deficit	$ 23,194