Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Capital Stock, Common	Additional Paid-in Capital	Retained Earnings	Treasury Stock
Balance at Dec. 31, 2013	$ 397,653	$ 907	$ 5,897	$ 432,034	$ (41,185)
Net income	84,834	0	0	84,834	0
Dividends on common stock	(7,034)	0	0	(7,034)	0
Stock-based compensation, net of tax	1,134	0	(1,839)	0	2,973
Balance at Dec. 31, 2014	476,587	907	4,058	509,834	(38,212)
Net income	73,056	0	0	73,056	0
Dividends on common stock	(6,942)	0	0	(6,942)	0
Stock Repurchased During Period, Value	(74,024)	0	0	0	(74,024)
Stock-based compensation, net of tax	1,251	0	68	0	1,183
Balance at Dec. 31, 2015	469,928	907	4,126	575,948	(111,053)
Net income	56,386	0	0	56,386	0
Dividends on common stock	(6,666)	0	0	(6,666)	0
Stock Repurchased During Period, Value	(14,678)	0	0	0	(14,678)
Stock-based compensation, net of tax	856	0	(693)	0	1,549
Balance at Dec. 31, 2016	$ 505,826	$ 907	$ 3,433	$ 625,668	$ (124,182)