Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Beginning balance at Dec. 31, 2018	$ 357,989	$ 39	$ 330,572	$ (586)	$ 27,964
Balance (in shares) at Dec. 31, 2018		39,015,034
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,266				13,266
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	896			896
Change in unrealized loss on investments	683
Issuance of common stock upon exercise of stock options	4,047		4,047
Issuance of common stock upon exercise of stock options (shares)		152,164
Stock Repurchased During Period, Shares		(94,090)
Treasury Stock, Value, Acquired, Cost Method	(7,871)		(1,129)		(6,742)
Adjustment To Additional Paid In Capital, Share-Based Compensation, Taxes Related To Net Share Settlements Of Equity Awards		(38,877)
Issuance of common stock upon vesting of restricted stock units (in shares)		99,601
Taxes from release of the restricted share units	(3,367)		(3,367)
Stock-based compensation	8,443		8,443
Ending balance at Mar. 31, 2019	373,403	$ 39	338,566	310	34,488
Balance (in shares) at Mar. 31, 2019		39,133,832
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained Earnings (Accumulated Deficit)	23,194
Beginning balance at Dec. 31, 2019	386,803	$ 39	362,408	1,162	23,194
Balance (in shares) at Dec. 31, 2019		39,146,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	18,694				18,694
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	391			391
Change in unrealized loss on investments	266
Issuance of common stock upon exercise of stock options	$ 4,714		4,714
Issuance of common stock upon exercise of stock options (shares)	144,989	144,989
Stock Repurchased During Period, Shares		(346,250)
Treasury Stock, Value, Acquired, Cost Method	$ (28,926)		(4,160)		(24,766)
Adjustment To Additional Paid In Capital, Share-Based Compensation, Taxes Related To Net Share Settlements Of Equity Awards		(58,598)
Issuance of common stock upon vesting of restricted stock units (in shares)		138,260
Taxes from release of the restricted share units	(5,000)		(5,000)
Stock-based compensation	10,054		10,054
Ending balance at Mar. 31, 2020	386,730	$ 39	$ 368,016	$ 1,553	$ 17,122
Balance (in shares) at Mar. 31, 2020		39,024,673
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained Earnings (Accumulated Deficit)	$ 17,122