Consolidated Investment Products (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 entity voting_interest_entity variable_interest_entity	Dec. 31, 2013
Variable Interest Entity [Line Items]
VIEs invested in and consolidated, number of entities	8
VOE invested in and consolidated, number of entities	1
Number of deconsolidated entities	4
Percentage of VIE general partnership interest	1.00%
Total assets	$ 20,462,500,000	$ 19,270,500,000
Pay interest at Libor or Euribor plus	15.00%
Collateral assets, default percentage	0.10%	0.80%
Outstanding balance on the notes issued by consolidated CLOs exceeds their fair value by approximately	200,000,000	200,000,000
Notes issued by collateralized loan obligations terms of arrangements interest rate margin spread low	0.21%
Notes issued by collateralized loan obligations terms of arrangements interest rate margin spread high	6.10%
CLO [Member]
Variable Interest Entity [Line Items]
Weighted average maturity (years)	9 years 8 months
Senior Secured Bank Loans And Bonds [Member] | CLO [Member]
Variable Interest Entity [Line Items]
Fair value, option, aggregate differences, long-term debt instruments	56,200,000	6,300,000
Private Equity Funds [Member]
Variable Interest Entity [Line Items]
Private Equity Funds, Weighted Average Remaining Term	2 years 7 months 6 days	2 years 9 months 0 days
Minimum [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Term	7 years
Maximum [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity Term	12 years
Level 3 Assets [Member]
Variable Interest Entity [Line Items]
Transfers, net	$ 0	$ 6,100,000