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, 2015	$ 116,160	$ 4	$ 6,715	$ 12,383	$ 113,531	$ (500)	$ (15,973)
Comprehensive income (loss):
Net income	31,184				31,184
Other comprehensive income	127					127
Dividends and dividend equivalents, net of estimated forfeitures	(2,063)				(2,063)
Share-based compensation	1,896			1,896
Stock shares awarded, forfeited or vested	506						506
Stock shares repurchased	(1,518)						(1,518)
Ending Balance at Dec. 31, 2016	146,292	4	6,715	14,279	142,652	(373)	(16,985)
Comprehensive income (loss):
Net income	41,823				41,823
Other comprehensive income	62					62
Dividends and dividend equivalents, net of estimated forfeitures	(17,346)				(17,346)
Share-based compensation	2,065			2,065
Stock shares awarded, forfeited or vested	497			(2,432)			2,929
Stock shares repurchased	(4,663)						(4,663)
Ending 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, 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)