Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Information
Revenues	$ 194,405	$ 192,601	$ 197,944	$ 202,005	$ 219,644	$ 211,306	$ 214,646	$ 218,011	$ 786,955	$ 863,607	$ 877,293
Amortization of intangible assets									(332)	(192)	0
Restructuring charges									(3,644)	(26,232)	(16,923)
Operating income from continuing operations	1,334	$ 1,588	$ 2,893	$ 5,936	4,007	$ (18,426)	$ (2,412)	$ 7,033	11,751	(9,798)	519
Long -lived assets by location
Goodwill	256,736				267,587				256,736	267,587	281,714
Foreign
Segment Information
Revenues									370,771	452,519	464,115
Long -lived assets by location
Long-lived assets	134,865				148,309				134,865	148,309
Goodwill	123,100				133,900				123,100	133,900
Domestic
Segment Information
Revenues									416,184	411,088	413,178
Long -lived assets by location
Long-lived assets	150,349				139,912				150,349	139,912
Goodwill	133,600				133,600				133,600	133,600
Netherlands
Segment Information
Revenues									80,959	104,163	121,875
Germany
Segment Information
Revenues									107,440	120,535	111,779
International
Long -lived assets by location
Goodwill	123,055				133,906				123,055	133,906	148,033
North America
Long -lived assets by location
Goodwill	$ 133,681				$ 133,681				133,681	133,681	133,681
Operating segments | International
Segment Information
Revenues									356,176	441,943	456,424
Operating income from continuing operations before amortization and restructuring									19,782	19,361	23,390
Operating segments | North America
Segment Information
Revenues									432,188	422,680	423,340
Operating income from continuing operations before amortization and restructuring									41,326	38,972	33,511
Operating segments | Other
Segment Information
Revenues									3,246	2,703	3,357
Operating income from continuing operations before amortization and restructuring									161	192	315
Inter-segment
Segment Information
Revenues									(4,655)	(3,719)	(5,828)
Corporate
Segment Information
Operating income from continuing operations before amortization and restructuring									(45,542)	(41,899)	(39,774)
Segment reconciling items
Segment Information
Operating income from continuing operations before amortization and restructuring									15,727	16,626	17,442
Amortization of intangible assets									(332)	(192)	0
Restructuring charges									$ (3,644)	$ (26,232)	$ (16,923)
Consolidated revenue | Customer concentration risk | Netherlands
Segment Information
Concentration risk percentage									10.00%
Consolidated revenue | Customer concentration risk | Germany
Segment Information
Concentration risk percentage									14.00%