CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment
Balance at beginning of period at Dec. 31, 2018	$ 394,567			$ 270,447		$ 124,120
Balance at beginning of period (in shares) at Dec. 31, 2018			43,864
Exercise of common stock options	9,502			9,502
Exercise of common stock options (in shares)			592
Restricted stock, net of forfeitures and shares withheld for taxes	(1,146)			(1,146)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			23
Stock-based compensation	16,324			16,324
Net income	10,151					10,151
Balance at end of period at Mar. 31, 2019	429,398			295,127		134,271
Balance at end of period (in shares) at Mar. 31, 2019			44,479
Balance at beginning of period at Dec. 31, 2018	394,567			270,447		124,120
Balance at beginning of period (in shares) at Dec. 31, 2018			43,864
Net income	57,373
Balance at end of period at Sep. 30, 2019	535,392			353,899		181,493
Balance at end of period (in shares) at Sep. 30, 2019			45,121
Balance at beginning of period at Mar. 31, 2019	429,398			295,127		134,271
Balance at beginning of period (in shares) at Mar. 31, 2019			44,479
Exercise of common stock options	7,473			7,473
Exercise of common stock options (in shares)			284
Restricted stock, net of forfeitures and shares withheld for taxes	(2,488)			(2,488)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			7
Stock-based compensation	21,390			21,390
Issuance of common stock under employee stock purchase plan	8,648			8,648
Issuance of common stock under employee stock purchase plan (in shares)			153
Net income	27,800					27,800
Balance at end of period at Jun. 30, 2019	492,221			330,150		162,071
Balance at end of period (in shares) at Jun. 30, 2019			44,923
Exercise of common stock options	4,936			4,936
Exercise of common stock options (in shares)			196
Restricted stock, net of forfeitures and shares withheld for taxes	(1,110)			(1,110)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			2
Stock-based compensation	19,923			19,923
Net income	19,422					19,422
Balance at end of period at Sep. 30, 2019	535,392			353,899		181,493
Balance at end of period (in shares) at Sep. 30, 2019			45,121
Balance at beginning of period at Dec. 31, 2019	$ 612,517	$ (388)		380,079		232,438	$ (388)
Balance at beginning of period (in shares) at Dec. 31, 2019			45,476
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Exercise of common stock options	$ 19,320			19,320
Exercise of common stock options (in shares)			539
Restricted stock, net of forfeitures and shares withheld for taxes	(4,893)			(4,893)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			20
Stock-based compensation	23,263			23,263
Other comprehensive income	158				$ 158
Net income	24,057					24,057
Balance at end of period at Mar. 31, 2020	674,034			417,769	158	256,107
Balance at end of period (in shares) at Mar. 31, 2020			46,035
Balance at beginning of period at Dec. 31, 2019	612,517	$ (388)		380,079		232,438	$ (388)
Balance at beginning of period (in shares) at Dec. 31, 2019			45,476
Net income	90,415
Balance at end of period at Sep. 30, 2020	832,627			510,017	145	322,465
Balance at end of period (in shares) at Sep. 30, 2020			46,945
Balance at beginning of period at Mar. 31, 2020	674,034			417,769	158	256,107
Balance at beginning of period (in shares) at Mar. 31, 2020			46,035
Exercise of common stock options	22,375			22,375
Exercise of common stock options (in shares)			431
Restricted stock, net of forfeitures and shares withheld for taxes	(2,836)			(2,836)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			61
Stock-based compensation	24,516			24,516
Issuance of common stock under employee stock purchase plan	15,035			15,035
Issuance of common stock under employee stock purchase plan (in shares)			202
Other comprehensive income	116				116
Net income	25,111					25,111
Balance at end of period at Jun. 30, 2020	758,351			476,859	274	281,218
Balance at end of period (in shares) at Jun. 30, 2020			46,729
Exercise of common stock options	12,247			12,247
Exercise of common stock options (in shares)			224
Restricted stock, net of forfeitures and shares withheld for taxes	(6,455)			(6,455)
Restricted stock, net of forfeitures and shares withheld for taxes (in shares)			(8)
Stock-based compensation	27,366			27,366
Other comprehensive income	(129)				(129)
Net income	41,247					41,247
Balance at end of period at Sep. 30, 2020	$ 832,627			$ 510,017	$ 145	$ 322,465
Balance at end of period (in shares) at Sep. 30, 2020			46,945