Segment Operating Results - Revenues Derived from Clients and Private Equity Funds by Geographical Areas (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Net Revenues	$ 407,070	$ 385,592	$ 1,166,767	$ 994,076
United States [Member]
Segment Reporting Information [Line Items]
Net Revenues	305,258	322,128	842,907	714,983
Europe and Other [Member]
Segment Reporting Information [Line Items]
Net Revenues	94,705	54,690	314,205	247,371
Latin America [Member]
Segment Reporting Information [Line Items]
Net Revenues	$ 7,107	$ 8,774	$ 9,655	$ 31,722