Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Repurchased Stock	Additional Paid-In Capital	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2012		17,751,945
Beginning balance at Dec. 31, 2012	$ 171,153	$ 178		$ 157,449	$ 13,526
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash (in shares)		237,482
Stock issued for cash	3,312	$ 2		3,310
Stock issued for director compensation (in shares)		2,802
Stock issued for director compensation	104			104
Repurchased shares of common and restricted stock from stockholders (in shares)		(20,540)	(394,064)
Repurchased shares of common and restricted stock from stockholders	(14,423)		$ (13,584)	(839)
Stock-based compensation	$ 4,024			4,024
Repurchased and retired shares of common stock (in shares)	394,064	394,064	394,064
Repurchased and retired shares of common stock	$ 0	$ (4)	$ 13,584		(13,580)
Excess tax benefit (expense) from stock based compensation	865			865
Net income	42,034				42,034
Ending balance at Dec. 31, 2013	207,069	$ 176		164,913	41,980
Ending balance (in shares) at Dec. 31, 2013		17,577,625
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash (in shares)		133,643
Stock issued for cash	537	$ 1		536
Stock issued for director compensation (in shares)		2,535
Stock issued for director compensation	90			90
Repurchased shares of common and restricted stock from stockholders (in shares)		(30,973)	(530,962)
Repurchased shares of common and restricted stock from stockholders	(19,712)		$ (18,470)	(1,242)
Stock-based compensation	5,107			5,107
Repurchased and retired shares of common stock (in shares)		530,962	530,962
Repurchased and retired shares of common stock	0	$ (5)	$ 18,470		(18,465)
Excess tax benefit (expense) from stock based compensation	250			250
Net income	40,877				40,877
Ending balance at Dec. 31, 2014	234,218	$ 172		169,654	64,392
Ending balance (in shares) at Dec. 31, 2014		17,151,868
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock issued for cash (in shares)		213,921
Stock issued for cash	55	$ 1		54
Stock issued for director compensation (in shares)		2,248
Stock issued for director compensation	66			66
Repurchased shares of common and restricted stock from stockholders (in shares)		(56,272)	(1,322,846)
Repurchased shares of common and restricted stock from stockholders	(35,310)		$ (33,526)	(1,784)
Stock-based compensation	$ 6,229			6,229
Repurchased and retired shares of common stock (in shares)	1,322,846	1,322,952	1,322,846
Repurchased and retired shares of common stock		$ (13)	$ 33,526		(33,513)
Excess tax benefit (expense) from stock based compensation	$ (519)			(519)
Net income	32,414				32,414
Ending balance at Dec. 31, 2015	$ 237,153	$ 160		$ 173,700	$ 63,293
Ending balance (in shares) at Dec. 31, 2015		15,988,813