Carried Interest Due from Investment Funds (Details) - Investment Funds - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Activity in the carried interest
Balance at beginning of quarter	$ 370	$ 71,019	$ 8,552	$ 70,906
Carried Interest recognized during the quarter	(17)	(1,158)	(365)	(1,045)
Cash received during the quarter	$ (353)	(61,314)	$ (8,187)	(61,314)
Balance at end of quarter		$ 8,547		$ 8,547