Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Total
Beginning Balance at Dec. 31, 2013	$ 173	$ 262,982	$ 8,401	$ 271,556
Beginning balance (in shares) at Dec. 31, 2013	17,258
Issuance of common stock	$ 40	81,524		81,564
Issuance of common stock, shares	4,000
Repurchase of common stock	$ (6)	(9,740)		(9,746)
Repurchase of common stock, shares	(608)
Repurchase of common stock upon vesting of restricted stock awards		(386)		(386)
Repurchase of common stock upon vesting of restricted stock awards, shares	(17)
Issuance of restricted stock awards, shares	250
Stock-based compensation expense	$ 2	2,150		2,152
Excess tax benefit of stock-based compensation		43		43
Forfeitures of restricted stock awards, shares	(7)
Net income			20,022	20,022
Ending Balance at Dec. 31, 2014	$ 209	336,573	28,423	365,205
Ending balance (in shares) at Dec. 31, 2014	20,876
Repurchase of common stock upon vesting of restricted stock awards		(861)		(861)
Repurchase of common stock upon vesting of restricted stock awards, shares	(44)
Issuance of restricted stock awards, shares	501
Stock-based compensation expense	$ 4	5,241		5,245
Forfeitures of restricted stock awards, shares	(29)
Net income			39,890	39,890
Ending Balance at Dec. 31, 2015	$ 213	340,953	68,313	409,479
Ending balance (in shares) at Dec. 31, 2015	21,304
Issuance of common stock	$ 6	11,363		11,369
Issuance of common stock, shares	578
Repurchase of common stock	$ (2)	(2,391)		(2,393)
Repurchase of common stock, shares	(159)
Repurchase of common stock upon vesting of restricted stock awards	$ (1)	(1,015)		(1,015)
Repurchase of common stock upon vesting of restricted stock awards, shares	(60)
Stock-based compensation expense		6,657		6,656
Forfeitures of restricted stock awards, shares	(42)
Net income			49,540	49,540
Ending Balance at Dec. 31, 2016	$ 216	$ 355,567	$ 117,853	$ 473,636
Ending balance (in shares) at Dec. 31, 2016	21,621