CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Capital Stock Preferred	Issued Common	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2017	$ 168,730	$ 4	$ 6,715	$ 13,912	$ 167,129	$ (311)	$ (18,719)
Comprehensive income (loss):
Net income	37,284				37,284
Other comprehensive income	147					147
Dividends and dividend equivalents per common shares and per restricted stock units, net of estimated forfeitures	(5,499)				(5,499)
Share-based compensation	2,687			2,687
Stock shares awarded, forfeited or vested	416			(1,224)			1,640
Stock shares repurchased	(2,324)						(2,324)
Ending Balance at Dec. 31, 2018	201,441	4	6,715	15,375	198,914	(164)	(19,403)
Comprehensive income (loss):
Net income	38,793				38,793
Other comprehensive income	(151)					(151)
Dividends and dividend equivalents per common shares and per restricted stock units, net of estimated forfeitures	(6,854)				(6,854)
Share-based compensation	2,453			2,453
Stock shares awarded, forfeited or vested	851			(3,799)			4,650
Stock shares repurchased	(5,489)						(5,489)
Adjustment related to Accounting Standards Update 2018-02 adoption	0				(69)	69
Ending Balance at Dec. 31, 2019	231,044	4	6,715	14,029	230,784	(246)	(20,242)
Comprehensive income (loss):
Net income	40,345				40,345
Other comprehensive income	732					732
Dividends and dividend equivalents per common shares and per restricted stock units, net of estimated forfeitures	(8,186)				(8,186)
Share-based compensation	2,067			2,067
Stock shares awarded, forfeited or vested	935			(593)			1,528
Stock shares repurchased	(4,411)						(4,411)
Ending Balance at Dec. 31, 2020	$ 262,526	$ 4	$ 6,715	$ 15,503	$ 262,943	$ 486	$ (23,125)