Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings
Balance (in shares) at Dec. 31, 2019		52,079
Balance at Dec. 31, 2019	$ 290,140	$ 208	$ 3,631	$ 286,301
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60,117			60,117
Stock options exercised and restricted stock awards granted (in shares)		616
Stock options exercised and restricted stock awards granted	18,519	$ 2	18,517
Share-based compensation	8,546		8,546
Stock repurchased and retired (in shares)		(430)
Stock repurchased and retired	(22,520)	$ (1)	(22,519)	0
Dividends	(9,910)			(9,910)
Balance (in shares) at Sep. 30, 2020		52,265
Balance at Sep. 30, 2020	344,892	$ 209	8,175	336,508
Balance (in shares) at Jun. 30, 2020		52,234
Balance at Jun. 30, 2020	322,695	$ 209	6,451	316,035
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	20,460			20,460
Stock options exercised and restricted stock awards granted (in shares)		126
Stock options exercised and restricted stock awards granted	4,346	$ 0	4,346
Share-based compensation	2,852		2,852
Stock repurchased and retired (in shares)		(95)
Stock repurchased and retired	(5,474)	$ 0	(5,474)	0
Dividends	13			13
Balance (in shares) at Sep. 30, 2020		52,265
Balance at Sep. 30, 2020	344,892	$ 209	8,175	336,508
Balance (in shares) at Dec. 31, 2020		52,225
Balance at Dec. 31, 2020	350,865	$ 209	5,161	345,495
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	52,572			52,572
Stock options exercised and restricted stock awards granted (in shares)		438
Stock options exercised and restricted stock awards granted	14,573	$ 2	14,571
Share-based compensation	8,784		8,784
Stock repurchased and retired (in shares)		(243)
Stock repurchased and retired	(16,551)	$ (1)	(16,550)	0
Dividends	(9,964)			(9,964)
Balance (in shares) at Sep. 30, 2021		52,420
Balance at Sep. 30, 2021	400,279	$ 210	11,966	388,103
Balance (in shares) at Jun. 30, 2021		52,416
Balance at Jun. 30, 2021	383,726	$ 210	10,998	372,518
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,581			15,581
Stock options exercised and restricted stock awards granted (in shares)		77
Stock options exercised and restricted stock awards granted	2,725	$ 0	2,725
Share-based compensation	2,991		2,991
Stock repurchased and retired (in shares)		(73)
Stock repurchased and retired	(4,748)	$ 0	(4,748)	0
Dividends	4			4
Balance (in shares) at Sep. 30, 2021		52,420
Balance at Sep. 30, 2021	$ 400,279	$ 210	$ 11,966	$ 388,103