Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings
Balance at Dec. 31, 2017	$ 366,351	$ 47	$ 403,906	$ (1,822)	$ (163,871)	$ 128,091
Balance (in shares) at Dec. 31, 2017		33,250,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from the sales of stock through the Employee Stock Purchase Plan (in shares)		2,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan	39		39
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		356,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions	3,763	$ 1	3,762
Purchases of treasury stock and buyback of shares for taxes (in shares)		(220,000)
Purchases of treasury stock and buyback of shares for taxes	(4,991)				(4,991)
Surrender of stock in conjunction with net working capital settlement (in shares)		(14,000)
Surrender of stock in conjunction with net working capital settlement	(303)				(303)
Net income	4,928					4,928
Foreign currency translation adjustment	(98)			(98)
Balance at Mar. 31, 2018	369,689	$ 48	407,707	(1,920)	(169,165)	133,019
Balance (in shares) at Mar. 31, 2018		33,374,000
Balance at Dec. 31, 2018	$ 353,684	$ 48	437,250	(2,588)	(233,676)	152,650
Balance (in shares) at Dec. 31, 2018	31,770,888	31,771,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Proceeds from the sales of stock through the Employee Stock Purchase Plan (in shares)		2,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan	$ 44		44
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		380,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions	4,248	$ 1	4,247
Purchases of treasury stock and buyback of shares for taxes (in shares)		(554,000)
Purchases of treasury stock and buyback of shares for taxes	(15,360)				(15,360)
Net income	7,026					7,026
Foreign currency translation adjustment	171			171
Balance at Mar. 31, 2019	$ 349,813	$ 49	$ 441,541	$ (2,417)	$ (249,036)	$ 159,676
Balance (in shares) at Mar. 31, 2019	31,599,081	31,599,000