Segment and Geographical Information - Revenues based on Geographical Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, net	$ 222,473	$ 243,509	$ 468,463	$ 483,082
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, net	189,032	197,901	396,912	394,005
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, net	18,830	30,155	42,108	59,256
Rest of World
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, net	14,611	15,453	29,443	29,821
Total Non-United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues, net	$ 33,441	$ 45,608	$ 71,551	$ 89,077