Investments of Operating Entities and Consolidated Funds - Variable Interest Entities (Details) - Variable Interest Entity, Not Primary Beneficiary - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Total assets of nonconsolidated variable interest entities	$ 3,100.0	$ 3,000.0
Total liabilities of nonconsolidated variable interest entities	472.4	499.2
Maximum exposure regarding nonconsolidated variable interest entities	$ 321.9	$ 260.9