Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Capital Stock, Common	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2012	$ 290,364	$ 907	$ 2,968	$ 368,313	$ (80,540)	$ (1,284)
Net income	70,582			70,582
Other comprehensive income, net of tax	1,284					1,284
Dividends on common stock	(6,861)			(6,861)
Stock Issued During Period, Value, Treasury Stock Reissued	41,100	0	1,745	0	39,355	0
Stock-based compensation, net of tax	1,184		1,184		0
Balance at Dec. 31, 2013	397,653	907	5,897	432,034	(41,185)	0
Net income	84,834	0	0	84,834	0	0
Other comprehensive income, net of tax	0	0	0	0	0
Dividends on common stock	(7,034)	0	0	(7,034)	0	0
Stock Issued During Period, Value, Treasury Stock Reissued	0
Stock-based compensation, net of tax	1,134	0	(1,839)	0	2,973	0
Balance at Dec. 31, 2014	476,587	907	4,058	509,834	(38,212)	0
Net income	73,056	0	0	73,056	0	0
Other comprehensive income, net of tax	0
Dividends on common stock	(6,942)	0	0	(6,942)	0	0
Stock Repurchased During Period, Value	(74,024)	0	0	0	(74,024)	0
Stock Issued During Period, Value, Treasury Stock Reissued	0
Stock-based compensation, net of tax	1,251	0	68	0	1,183	0
Balance at Dec. 31, 2015	$ 469,928	$ 907	$ 4,126	$ 575,948	$ (111,053)	$ 0