Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings
Balance at Dec. 31, 2018	$ 249,443	$ 208	$ 0	$ 249,235
Balance (in shares) at Dec. 31, 2018		51,991
Net income	36,438			36,438
Stock options exercised and restricted stock awards granted	11,283	$ 2	11,281
Stock options exercised and restricted stock awards granted (in shares)		494
Share-based compensation	9,854		9,854
Stock repurchased and retired	(16,460)	$ (1)	(16,459)
Stock repurchased and retired (in shares)		(366)
Balance at Sep. 30, 2019	282,255	$ 209	4,676	277,370
Balance (in shares) at Sep. 30, 2019		52,119
Dividends, Common Stock, Cash	(8,303)			(8,303)
Balance at Jun. 30, 2019	267,511	$ 209	4,299	263,003
Balance (in shares) at Jun. 30, 2019		52,118
Net income	14,290			14,290
Stock options exercised and restricted stock awards granted	3,598		3,598
Stock options exercised and restricted stock awards granted (in shares)		110
Share-based compensation	2,068		2,068
Stock repurchased and retired	(5,289)		(5,289)
Stock repurchased and retired (in shares)		(109)
Balance at Sep. 30, 2019	282,255	$ 209	4,676	277,370
Balance (in shares) at Sep. 30, 2019		52,119
Dividends, Common Stock, Cash	77			77
Balance at Dec. 31, 2019	290,140	$ 208	3,631	286,301
Balance (in shares) at Dec. 31, 2019		52,079
Net income	60,117			60,117
Stock options exercised and restricted stock awards granted	18,519	$ 2	18,517
Stock options exercised and restricted stock awards granted (in shares)		616
Share-based compensation	8,546		8,546
Stock repurchased and retired	(22,520)	$ (1)	(22,519)
Stock repurchased and retired (in shares)		(430)
Balance at Sep. 30, 2020	344,892	$ 209	8,175	336,508
Balance (in shares) at Sep. 30, 2020		52,265
Dividends, Common Stock, Cash	(9,910)			(9,910)
Balance at Jun. 30, 2020	322,695	$ 209	6,451	316,035
Balance (in shares) at Jun. 30, 2020		52,234
Net income	20,460			20,460
Stock options exercised and restricted stock awards granted	4,346	$ 0	4,346
Stock options exercised and restricted stock awards granted (in shares)		126
Share-based compensation	2,852		2,852
Stock repurchased and retired	(5,474)		(5,474)	0
Stock repurchased and retired (in shares)		(95)
Balance at Sep. 30, 2020	344,892	$ 209	$ 8,175	336,508
Balance (in shares) at Sep. 30, 2020		52,265
Dividends, Common Stock, Cash	$ 13			$ 13