Accrued Performance Fees - Components of Accrued Performance Fees (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accrued Performance Fees Disclosure [Line Items]
Accrued performance fees	$ 3,838.0	$ 3,653.6
Corporate Private Equity [Member]
Accrued Performance Fees Disclosure [Line Items]
Accrued performance fees	2,776.1	2,830.4
Global Market Strategies [Member]
Accrued Performance Fees Disclosure [Line Items]
Accrued performance fees	162.4	167.2
Real Assets [Member]
Accrued Performance Fees Disclosure [Line Items]
Accrued performance fees	332.6	277.2
Solutions [Member]
Accrued Performance Fees Disclosure [Line Items]
Accrued performance fees	$ 566.9	$ 378.8