Segment Information (Long-lived assets by Geographic Location) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Property and equipment, net of accumulated depreciation	$ 159,153	$ 166,636
United States
Segment Reporting Information [Line Items]
Property and equipment, net of accumulated depreciation	112,640	104,939
Europe
Segment Reporting Information [Line Items]
Property and equipment, net of accumulated depreciation	26,329	39,976
Other Geographic Locations
Segment Reporting Information [Line Items]
Property and equipment, net of accumulated depreciation	$ 20,184	$ 21,721