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, 2017		52,422
Balance at Dec. 31, 2017	$ 238,925	$ 210	$ 0	$ 238,715
Net income	42,329			42,329
Stock options exercised and restricted stock awards granted (in shares)		353
Stock options exercised and restricted stock awards granted	4,987	$ 1	4,986
Share-based compensation	7,862		7,862
Stock repurchased and retired (in shares)		(784)
Stock repurchased and retired	(27,943)	$ (3)	(12,848)	(15,092)
Dividends	(16,717)			(16,717)
Balance (in shares) at Dec. 31, 2018		51,991
Balance at Dec. 31, 2018	249,443	$ 208	0	249,235
Net income	53,711			53,711
Stock options exercised and restricted stock awards granted (in shares)		542
Stock options exercised and restricted stock awards granted	12,625	$ 2	12,623
Share-based compensation	11,799		11,799
Stock repurchased and retired (in shares)		(454)
Stock repurchased and retired	(20,793)	$ (2)	(20,791)	0
Dividends	(16,645)			(16,645)
Balance (in shares) at Dec. 31, 2019		52,079
Balance at Dec. 31, 2019	290,140	$ 208	3,631	286,301
Net income	79,009			79,009
Stock options exercised and restricted stock awards granted (in shares)		712
Stock options exercised and restricted stock awards granted	21,418	$ 3	21,415
Share-based compensation	11,342		11,342
Stock repurchased and retired (in shares)		(566)
Stock repurchased and retired	(31,229)	$ (2)	(31,227)	0
Dividends	(19,815)			(19,815)
Balance (in shares) at Dec. 31, 2020		52,225
Balance at Dec. 31, 2020	$ 350,865	$ 209	$ 5,161	$ 345,495