Investments of Operating Entities and Consolidated Funds - Other Investments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Investment Holdings [Line Items]
Other investments	$ 114,551	$ 99,483
Other Investments, Consolidated Funds	198,564	187,480
Real Estate Equity Investment
Investment Holdings [Line Items]
Other investments	2,262	2,088
Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	83,967	71,051
Other Investments, Consolidated Funds	194,474	182,638
Equity Method Investments
Investment Holdings [Line Items]
Other investments	27,904	25,966
Lehman claims, at fair value
Investment Holdings [Line Items]
Other investments	418	378
Other Investments, Consolidated Funds	4,090	4,842
RCG RE Manager, LLC | Real Estate Equity Investment
Investment Holdings [Line Items]
Other investments	$ 2,300	$ 2,100