Segment Reporting - Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Total plant, equipment and leasehold improvement additions	$ 3,140	$ 4,451
Revenues	86,393	77,310
Total long-lived assets	178,815		$ 179,224
Total North America
Segment Reporting Information [Line Items]
Total plant, equipment and leasehold improvement additions	2,516	4,358
Revenues	78,435	68,988
Total long-lived assets	166,179		166,631
U.S.
Segment Reporting Information [Line Items]
Total plant, equipment and leasehold improvement additions	2,402	4,174
Revenues	74,436	67,835
Total long-lived assets	163,736		164,377
Canada
Segment Reporting Information [Line Items]
Total plant, equipment and leasehold improvement additions	114	184
Revenues	3,999	1,153
Total long-lived assets	2,443		2,254
U.K.
Segment Reporting Information [Line Items]
Total plant, equipment and leasehold improvement additions	624	93
Revenues	6,605	6,205
Total long-lived assets	12,636		$ 12,593
Other
Segment Reporting Information [Line Items]
Revenues	$ 1,353	$ 2,117