Segment Information - Property and Equipment, Net by Location (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 697,715	$ 715,812
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	661,421	676,968
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	32,793	33,628
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	3,501	5,216
Total revenues outside of the United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total property and equipment, net	$ 36,294	$ 38,844