Industry Segment and Geographic Areas (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2016 USD ($) segment	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting [Abstract]
Number of segments | segment									1
Revenues from External Customers and Long-Lived Assets
Revenues	$ 93,098	$ 96,273	$ 103,820	$ 100,570	$ 95,770	$ 99,388	$ 98,896	$ 83,644	$ 393,761	$ 377,698	$ 364,768
Long-lived assets	90,194				90,920				90,194	90,920
Total assets	349,699				355,480				349,699	355,480
United States
Revenues from External Customers and Long-Lived Assets
Revenues									347,853	322,535	309,651
Long-lived assets	53,454				53,615				53,454	53,615
Total assets	287,081				289,447				287,081	289,447
Asia
Revenues from External Customers and Long-Lived Assets
Revenues									6,539	8,299	10,647
Canada
Revenues from External Customers and Long-Lived Assets
Revenues									12,587	9,095	12,092
Europe
Revenues from External Customers and Long-Lived Assets
Revenues									15,299	17,036	19,448
Long-lived assets	15,694				15,676				15,694	15,676
Total assets	38,579				40,813				38,579	40,813
Mexico
Revenues from External Customers and Long-Lived Assets
Revenues									3,460	8,889	3,941
Long-lived assets	21,046				21,629				21,046	21,629
Total assets	$ 24,039				$ 25,220				24,039	25,220
Middle East
Revenues from External Customers and Long-Lived Assets
Revenues									5,520	9,672	6,221
Other
Revenues from External Customers and Long-Lived Assets
Revenues									$ 2,503	$ 2,172	$ 2,768