Unaudited Condensed Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss	Treasury Stock	Retained Earnings
Balance at Dec. 31, 2017		$ 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)		4,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan			81
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		392,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions		$ 1	7,614
Purchases of treasury stock and buyback of shares for taxes (in shares)		(557,000)
Purchases of treasury stock and buyback of shares for taxes					(13,127)
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)
Issuance of stock in conjunction with acquisition			3,009
Issuance of stock in conjunction with acquisition (in shares)		153,000
Foreign currency translation adjustment	$ (652)			(652)
Net income	10,778					10,778
Balance at Jun. 30, 2018	373,752	$ 48	414,610	(2,474)	(177,301)	138,869
Balance (in shares) at Jun. 30, 2018		33,228,000
Balance at Mar. 31, 2018		$ 48	407,707	(1,920)	(169,165)	133,020
Balance (in shares) at Mar. 31, 2018		33,374,000
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			42
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		36,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions		$ 0	3,852
Purchases of treasury stock and buyback of shares for taxes (in shares)		(337,000)
Purchases of treasury stock and buyback of shares for taxes					(8,136)
Surrender of stock in conjunction with net working capital settlement (in shares)		0
Surrender of stock in conjunction with net working capital settlement					0
Issuance of stock in conjunction with acquisition			3,009
Issuance of stock in conjunction with acquisition (in shares)		153,000
Foreign currency translation adjustment	(554)			(554)
Net income	5,849					5,849
Balance at Jun. 30, 2018	$ 373,752	$ 48	414,610	(2,474)	(177,301)	138,869
Balance (in shares) at Jun. 30, 2018		33,228,000
Balance (in shares) at Jun. 30, 2019	0
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)		4,000
Proceeds from the sales of stock through the Employee Stock Purchase Plan			85
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		414,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions		$ 1	8,355
Purchases of treasury stock and buyback of shares for taxes (in shares)		(717,000)
Purchases of treasury stock and buyback of shares for taxes					(20,225)
Surrender of stock in conjunction with net working capital settlement (in shares)		0
Surrender of stock in conjunction with net working capital settlement					0
Issuance of stock in conjunction with acquisition			1,456
Issuance of stock in conjunction with acquisition (in shares)		54,000
Foreign currency translation adjustment	$ 237			237
Net income	15,554					15,554
Balance at Jun. 30, 2019	$ 359,147	$ 49	447,146	(2,351)	(253,901)	168,204
Balance (in shares) at Jun. 30, 2019	31,526,154	31,526,000
Balance (in shares) at Jun. 30, 2019	0
Balance at Mar. 31, 2019		$ 49	441,541	(2,417)	(249,036)	159,676
Balance (in shares) at Mar. 31, 2019		31,599,000
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			41
Stock compensation related to restricted stock vesting and retirement savings plan contributions (in shares)		34,000
Stock compensation related to restricted stock vesting and retirement savings plan contributions		$ 0	4,108
Purchases of treasury stock and buyback of shares for taxes (in shares)		(163,000)
Purchases of treasury stock and buyback of shares for taxes					(4,865)
Surrender of stock in conjunction with net working capital settlement (in shares)		0
Surrender of stock in conjunction with net working capital settlement					0
Issuance of stock in conjunction with acquisition			1,456
Issuance of stock in conjunction with acquisition (in shares)		54,000
Foreign currency translation adjustment	$ 66			66
Net income	8,528					8,528
Balance at Jun. 30, 2019	$ 359,147	$ 49	$ 447,146	$ (2,351)	$ (253,901)	$ 168,204
Balance (in shares) at Jun. 30, 2019	31,526,154	31,526,000