Revenues and Business Information - Schedule of Geographical Distribution of Revenues and Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	$ 885,840	$ 684,615	$ 613,373
Total assets	914,375	699,068
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	731,265	535,985	516,688
Total assets	756,053	519,933
Europe
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	95,844	111,088	54,332
Total assets	55,064	83,834
Rest of World
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	58,731	37,542	$ 42,353
Total assets	$ 103,258	$ 95,301