Investments of Operating Entities and Consolidated Funds Securities borrowed and securities loaned (Details) - USD ($)		Sep. 30, 2017	Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Securities Borrowed, Gross		$ 371,367,000
Gross amounts recognized		371,367,000	$ 0
Securities borrowed, additional amounts, asset		(12,694,000)
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition (a)	[1]	0
Financial instruments		358,673,000
Cash Collateral pledged (b)		0
Net amounts		0
Securities Loaned, Gross		414,957,000
Gross amounts recognized		414,957,000	$ 0
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition (a)	[1]	0
Additional Amounts Available		(7,251,000)
Financial instruments		407,706,000
Cash Collateral pledged (b)		0
Net amounts		$ 0

[1] Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred.