Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance (in shares) at Dec. 31, 2014		10,952,268
Beginning Balance at Dec. 31, 2014	$ 256,570	$ 110	$ 0	$ 72,206	$ 190,905	$ (6,651)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(74,879)				(74,879)
Other comprehensive income (loss), net of tax	1,048					1,048
Stock options exercised (in shares)		167,523
Stock options exercised	3,084	$ 1		3,083
Stock repurchased related to the exercise of stock options (in shares)		(137,194)
Stock repurchased related to the exercise of stock options	(4,210)	$ (1)		(4,209)
Stock awards vested (in shares)		101,721
Stock awards vested	0	$ 1		(1)
Stock-based compensation	3,495			3,495
Excess tax benefits or shortfall from share-based compensation	626			626
Ending Balance (in shares) at Dec. 31, 2015		11,084,318
Ending Balance at Dec. 31, 2015	185,734	$ 111	0	75,200	116,026	(5,603)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	25,261				25,261
Other comprehensive income (loss), net of tax	(476)					(476)
Stock options exercised (in shares)		132,325
Stock options exercised	2,122	$ 1		2,121
Stock repurchased related to the exercise of stock options (in shares)		(151,916)
Stock repurchased related to the exercise of stock options	(3,465)	$ (1)		(3,464)
Stock awards vested (in shares)		129,086
Stock awards vested	0	$ 1		(1)
Stock-based compensation	3,007			3,007
Excess tax benefits or shortfall from share-based compensation	(80)			(80)
Ending Balance (in shares) at Dec. 31, 2016		11,193,813
Ending Balance at Dec. 31, 2016	212,103	$ 112	0	76,783	141,287	(6,079)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	20,077				20,077
Other comprehensive income (loss), net of tax	$ (38)					(38)
Stock options exercised (in shares)	212,775	212,775
Stock options exercised	$ 4,336	$ 2		4,334
Stock repurchased related to the exercise of stock options (in shares)		(219,164)
Stock repurchased related to the exercise of stock options	(6,904)	$ (2)		(6,902)
Stock awards vested (in shares)		145,417
Stock awards vested	0	$ 1		(1)
Stock-based compensation	6,009			6,009
Ending Balance (in shares) at Dec. 31, 2017		11,332,841
Ending Balance at Dec. 31, 2017	$ 235,583	$ 113	$ 0	$ 80,223	$ 161,364	$ (6,117)