Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Repurchased Stock	Additional Paid-In Capital	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2015		0	15,988,813	0
Beginning balance at Dec. 31, 2015	$ 237,153	$ 0	$ 160	$ 0	$ 173,700	$ 63,293
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee benefit plans (in shares)			169,592
Issuance of common stock under employee benefit plans	119		$ 1		118
Repurchased shares of common and restricted stock from stockholders (in shares)			(49,512)
Repurchased shares of common and restricted stock from stockholders	(848)				(848)
Stock-based compensation	5,211				5,211
Excess tax benefit from stock based compensation	(1,120)				(1,120)
Net income	24,155					24,155
Ending balance (in shares) at Dec. 31, 2016		0	16,108,893	0
Ending balance at Dec. 31, 2016	264,670	$ 0	$ 161	$ 0	177,061	87,448
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee benefit plans (in shares)			226,986
Issuance of common stock under employee benefit plans	98		$ 2		96
Repurchased shares of common and restricted stock from stockholders (in shares)			(68,065)
Repurchased shares of common and restricted stock from stockholders	(1,587)				(1,587)
Stock-based compensation	5,104				5,104
Net income	21,121					21,121
Ending balance (in shares) at Dec. 31, 2017		0	16,267,814	0
Ending balance at Dec. 31, 2017	289,406	$ 0	$ 163	$ 0	180,674	108,569
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee benefit plans (in shares)			223,059
Issuance of common stock under employee benefit plans	0		$ 2		(2)
Repurchased shares of common and restricted stock from stockholders (in shares)			(66,088)
Repurchased shares of common and restricted stock from stockholders	(1,823)		$ (1)		(1,822)
Stock-based compensation	8,322				8,322
Net income	25,639					25,639
Ending balance (in shares) at Dec. 31, 2018		0	16,424,785	0
Ending balance at Dec. 31, 2018	$ 321,266	$ 0	$ 164	$ 0	$ 187,172	$ 133,930