Business Segments (Details 3) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenue	$ 127,283	$ 121,978	$ 125,542	$ 115,756	$ 126,431	$ 122,931	$ 125,665	$ 115,253	$ 490,559	$ 490,280	$ 501,867
United States
Segment Reporting Information [Line Items]
Revenue									339,329	341,581	380,052
United Kingdom
Segment Reporting Information [Line Items]
Revenue									93,017	98,991	83,652
Other Countries
Segment Reporting Information [Line Items]
Revenue									$ 58,213	$ 49,708	$ 38,163