Investments of Operating Entities and Consolidated Funds - Variable Interest Entities (Details) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Total assets of nonconsolidated variable interest entities	$ 2,200,000,000	$ 1,700,000,000
Total liabilities of nonconsolidated variable interest entities	225,500,000	242,500,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Maximum exposure regarding nonconsolidated variable interest entities	$ 182,100,000	$ 193,900,000