Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Components of accrued expenses
Accrued investment manager fees	$ 45,505	$ 39,324
Accrued compensation and related taxes	27,927	43,724
Purchase consideration liabilities	13,171	856
Sales and use tax payable	9,200	9,037
Accrued professional services	2,639	4,985
Accrued interest	1,640
Definite consideration		1,250
Other accrued expenses	10,516	6,721
Total accrued expenses	$ 110,598	$ 105,897