Consolidated Investment Entities (Fair Value Hierarchy) (Details) (USD $) In Millions, unless otherwise specified																																																	9 Months Ended
	Sep. 30, 2014 Measured at fair value on a recurring basis	Dec. 31, 2013 Measured at fair value on a recurring basis	Sep. 30, 2014 Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis	Dec. 31, 2013 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis	Sep. 30, 2014 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 VOEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 VOEs Limited Partnerships Measured at fair value on a recurring basis	Dec. 31, 2013 VOEs Limited Partnerships Measured at fair value on a recurring basis	Sep. 30, 2014 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 VOEs Limited Partnerships Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis	Dec. 31, 2013 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis	Sep. 30, 2014 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 VIEs Cash and Cash Equivalents Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 VIEs Corporate Loans Measured at fair value on a recurring basis	Dec. 31, 2013 VIEs Corporate Loans Measured at fair value on a recurring basis	Sep. 30, 2014 VIEs Corporate Loans Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 VIEs Corporate Loans Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 VIEs Corporate Loans Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 VIEs Corporate Loans Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 VIEs Corporate Loans Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 VIEs Corporate Loans Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis	Dec. 31, 2013 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis	Sep. 30, 2014 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 1	Dec. 31, 2013 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 1	Sep. 30, 2014 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 2	Dec. 31, 2013 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 2	Sep. 30, 2014 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 3	Dec. 31, 2013 VIEs Collateralized Debt Obligations Measured at fair value on a recurring basis Level 3	Sep. 30, 2014 Senior Secured Floating Rate Leveraged Loans VIEs Collateralized Debt Obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Weighted average maturity																																																	9 years 1 month 6 days
Assets	$ 10,666.6	$ 8,894.6	$ 560.9	$ 710.7	$ 7,110.9	$ 5,424.3	$ 2,994.8	$ 2,759.6	$ 106.7	$ 68.2	$ 106.7	$ 68.2	$ 0	$ 0	$ 0	$ 0	$ 3,842.8	$ 3,218.6	$ 0	$ 0	$ 867.3	$ 484.5	$ 2,975.5	$ 2,734.1	$ 454.2	$ 642.5	$ 454.2	$ 642.5	$ 0	$ 0	$ 0	$ 0	$ 6,262.9	$ 4,965.3	$ 0	$ 0	$ 6,243.6	$ 4,939.8	$ 19.3	$ 25.5
Liabilities	$ 6,344.4	$ 5,161.6	$ 0	$ 0	$ 0	$ 0	$ 6,344.4	$ 5,161.6																																	$ 6,344.4	$ 5,161.6	$ 0	$ 0	$ 0	$ 0	$ 6,344.4	$ 5,161.6