Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Total
Beginning balance at Dec. 31, 2018	$ 302	$ 595,037	$ 264,020	$ 859,359
Beginning balance (in shares) at Dec. 31, 2018	30,155,000
Repurchase of common stock		(1,438)		$ (1,438)
Repurchase of common stock, shares	(83,000)			(83,000)
Vesting of restricted stock units	$ 3	(3)
Vesting of restricted stock units, shares	367,000
Withholding of common stock upon vesting of restricted stock units	$ (2)	(3,164)		$ (3,166)
Withholding of common stock upon vesting of restricted stock units, shares	(135,000)
Stock-based compensation expense		3,534		3,534
Net income			17,117	17,117
Ending balance at Mar. 31, 2019	$ 303	593,966	281,137	875,406
Ending balance (in shares) at Mar. 31, 2019	30,304,000
Beginning balance at Dec. 31, 2019	$ 331	684,354	377,014	1,061,699
Beginning balance (in shares) at Dec. 31, 2019	33,067,000
Repurchase of common stock
Repurchase of common stock, shares
Vesting of restricted stock units	$ 4	(4)
Vesting of restricted stock units, shares	412,000
Withholding of common stock upon vesting of restricted stock units	$ (2)	(4,975)		$ (4,977)
Withholding of common stock upon vesting of restricted stock units, shares	(160,000)
Stock-based compensation expense		1,685		1,685
Net income			26,126	26,126
Ending balance at Mar. 31, 2020	$ 333	$ 681,060	$ 403,140	$ 1,084,533
Ending balance (in shares) at Mar. 31, 2020	33,319,000