Segment Reporting (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) segment	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Segment Reporting
Number of operating segments | segment			4
Segment reporting
Total revenues	$ 140,494	$ 138,466	$ 290,221	$ 276,075
Income (loss) before income tax expense (benefit) (1)	(8,949)	16,688	13,391	35,108
Identifiable assets	1,678,495	1,470,338	1,678,495	1,470,338	$ 1,350,849
Reserve for probable settlement with SEC	20,300
Legal and related costs	2,300
U.S. Operations
Segment reporting
Total revenues	75,474	77,266	155,928	152,873
Income (loss) before income tax expense (benefit) (1)	5,735	9,861	16,791	20,117
Identifiable assets	1,209,355	984,027	1,209,355	984,027
Canadian Operations
Segment reporting
Total revenues	16,705	17,794	35,617	37,012
Income (loss) before income tax expense (benefit) (1)	3,615	4,060	7,369	8,570
Identifiable assets	96,370	106,834	96,370	106,834
European Operations
Segment reporting
Total revenues	33,574	31,064	70,180	63,854
Income (loss) before income tax expense (benefit) (1)	7,763	8,789	18,893	19,613
Identifiable assets	286,607	317,532	286,607	317,532
Asia Pacific Operations
Segment reporting
Total revenues	14,512	12,063	28,034	21,760
Income (loss) before income tax expense (benefit) (1)	1,602	(314)	2,709	(2,132)
Identifiable assets	86,163	61,945	86,163	61,945
Corporate
Segment reporting
Total revenues	229	279	462	576
Income (loss) before income tax expense (benefit) (1)	$ (27,664)	$ (5,708)	$ (32,371)	$ (11,060)