Segment Reporting - Financial Information (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment reporting
Number of operating segments | segment			4
Total revenues	$ 128,477		$ 259,961
(Loss) income before income tax (benefit) expense	(254)	$ 5,087	5,643	$ 8,898
Identifiable assets	926,934		926,934		$ 784,856
Expense incurred as potential settlement with SEC	12,000		12,000
Legal expenses	200		200
Restructuring charges			7,165
Litigation settlement amount			18,000
US | Restatement Adjustment
Segment reporting
Restructuring charges			7,200
Increase (decrease) in expenses		(2,700)		(5,300)
Canada | Restatement Adjustment
Segment reporting
Increase (decrease) in expenses		700		1,300
Europe | Restatement Adjustment
Segment reporting
Increase (decrease) in expenses		1,300		2,500
Asia Pacific | Restatement Adjustment
Segment reporting
Increase (decrease) in expenses		700		1,500
U.S. Operations
Segment reporting
Total revenues	48,026		96,512
(Loss) income before income tax (benefit) expense	(988)		(2,354)
Identifiable assets	400,709		400,709
Canadian Operations
Segment reporting
Total revenues	17,730		35,777
(Loss) income before income tax (benefit) expense	3,050		6,879
Identifiable assets	110,536		110,536
European Operations
Segment reporting
Total revenues	42,911		87,741
(Loss) income before income tax (benefit) expense	10,440		22,349
Identifiable assets	341,736		341,736
Asia Pacific Operations
Segment reporting
Total revenues	19,430		39,037
(Loss) income before income tax (benefit) expense	4,000		8,680
Identifiable assets	73,953		73,953
Corporate Activity
Segment reporting
Total revenues	380		894
(Loss) income before income tax (benefit) expense	(16,756)		(29,911)
Corporate
Segment reporting
Total revenues	$ 380		$ 894
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Segment reporting
Total revenues		121,581		242,416
(Loss) income before income tax (benefit) expense		5,087		8,898
Identifiable assets		956,676		956,676
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | U.S. Operations
Segment reporting
Total revenues		52,763		106,156
(Loss) income before income tax (benefit) expense		(2,370)		(6,313)
Identifiable assets		456,071		456,071
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Canadian Operations
Segment reporting
Total revenues		15,984		32,466
(Loss) income before income tax (benefit) expense		2,465		5,296
Identifiable assets		108,698		108,698
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | European Operations
Segment reporting
Total revenues		38,739		75,451
(Loss) income before income tax (benefit) expense		9,570		19,508
Identifiable assets		339,337		339,337
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Asia Pacific Operations
Segment reporting
Total revenues		13,720		27,663
(Loss) income before income tax (benefit) expense		799		1,913
Identifiable assets		52,570		52,570
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Corporate Activity
Segment reporting
Total revenues		375		680
(Loss) income before income tax (benefit) expense		(5,377)		(11,506)
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Corporate
Segment reporting
Total revenues		$ 375		$ 680