CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings
Beginning balance at Dec. 31, 2014	$ 279,059	$ 2	$ 126,678	$ 152,379
Beginning balance (shares) at Dec. 31, 2014		21,978,762
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	80,246			80,246
Purchase of common stock for tax withholding, net	(3,824)		(3,824)
Purchase of common stock for tax withholding, net (shares)		(217,211)
Amortization of stock based compensation	1,868		1,868
Cash dividends declared	(13,498)			(13,498)
Common stock repurchase program	(15,008)		(15,008)
Common stock repurchase program (shares)		(897,177)
Issuance of restricted common stock under the Equity Plan (shares)		21,887
Other	721		721
Ending balance at Dec. 31, 2015	329,564	$ 2	110,435	219,127
Ending balance (shares) at Dec. 31, 2015		20,886,261
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	13,979			13,979
Issuance of common stock under the Employee Stock Purchase Plan	53		53
Issuance of common stock under the Employee Stock Purchase Plan (shares)		3,961
Purchased and retired common stock and other (shares)		(2)
Amortization of stock based compensation	854		854
Cash dividends declared	(15,766)			(15,766)
Common stock repurchase program	(6,489)		(6,489)
Common stock repurchase program (shares)		(388,255)
Issuance of restricted common stock under the Equity Plan (shares)		23,649
Other	(108)		(43)	(65)
Ending balance at Dec. 31, 2016	322,087	$ 2	104,810	217,275
Ending balance (shares) at Dec. 31, 2016		20,525,614
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(15,306)			(15,306)
Issuance of common stock under the Employee Stock Purchase Plan	256		256
Issuance of common stock under the Employee Stock Purchase Plan (shares)		17,760
Issuance of common stock for vested restricted stock units under the Equity Plan (shares)		143,394
Amortization of stock based compensation	3,688		3,688
Cash dividends declared	(10,332)			(10,332)
Common stock repurchase program	(10,023)		(10,023)
Common stock repurchase program (shares)		(572,550)
Issuance of restricted common stock under the Equity Plan (shares)		21,296
Other	159			159
Ending balance at Dec. 31, 2017	$ 290,529	$ 2	$ 98,731	$ 191,796
Ending balance (shares) at Dec. 31, 2017		20,135,514