Consolidated Investment Entities (Details) (USD $)	9 Months Ended																2 Months Ended	9 Months Ended		12 Months Ended													9 Months Ended				9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Consolidated investment entities fund Collateral	Dec. 31, 2013 Consolidated investment entities Collateral fund	Sep. 30, 2014 Consolidated investment entities VOEs	Dec. 31, 2013 Consolidated investment entities VOEs	Sep. 30, 2014 Consolidated investment entities VOEs Cash and Cash Equivalents	Dec. 31, 2013 Consolidated investment entities VOEs Cash and Cash Equivalents	Sep. 30, 2014 Consolidated investment entities VOEs Limited Partnerships/Corporations	Dec. 31, 2013 Consolidated investment entities VOEs Limited Partnerships/Corporations	Sep. 30, 2014 Consolidated investment entities VOEs Other assets	Dec. 31, 2013 Consolidated investment entities VOEs Other assets	Sep. 30, 2014 Consolidated investment entities VOEs Other Liabilities	Dec. 31, 2013 Consolidated investment entities VOEs Other Liabilities	Sep. 30, 2014 Private Equity Funds VOEs	Dec. 31, 2013 Private Equity Funds VOEs	Jul. 31, 2014 LIBOR Line of Credit	Sep. 30, 2014 LIBOR Line of Credit	Sep. 30, 2014 EURIBOR Private Equity Funds VOEs	Dec. 31, 2013 EURIBOR Line of Credit	Sep. 30, 2014 VIEs Consolidated investment entities	Dec. 31, 2013 VIEs Consolidated investment entities	Sep. 30, 2014 VIEs Consolidated investment entities Cash and Cash Equivalents	Dec. 31, 2013 VIEs Consolidated investment entities Cash and Cash Equivalents	Sep. 30, 2014 VIEs Consolidated investment entities Corporate Loans	Dec. 31, 2013 VIEs Consolidated investment entities Corporate Loans	Sep. 30, 2014 VIEs Consolidated investment entities Other assets	Dec. 31, 2013 VIEs Consolidated investment entities Other assets	Sep. 30, 2014 VIEs Consolidated investment entities Collateralized Debt Obligations	Dec. 31, 2013 VIEs Consolidated investment entities Collateralized Debt Obligations	Sep. 30, 2014 VIEs Consolidated investment entities Other Liabilities	Dec. 31, 2013 VIEs Consolidated investment entities Other Liabilities	Sep. 30, 2014 VIEs Senior Secured Floating Rate Leveraged Loans Collateralized Debt Obligations	May 28, 2014 VIEs Senior Secured Floating Rate Leveraged Loans Collateralized Debt Obligations	Sep. 30, 2014 VIEs Senior Secured Corporate Loans Corporate Loans	Dec. 31, 2013 VIEs Senior Secured Corporate Loans Corporate Loans	Sep. 30, 2014 VIEs LIBOR Senior Secured Floating Rate Leveraged Loans Collateralized Debt Obligations
Variable Interest Entity [Line Items]
Basis spread																	1.40%	1.60%		2.20%
Weighted average maturity																																	9 years 1 month 6 days
Investments	$ 89,824,400,000	$ 87,050,800,000	$ 732,700,000	$ 654,000,000
Consolidated collateral loan obligations			15	12
Consolidated funds			35	35
Assets of consolidated investment entities			10,842,700,000	8,999,400,000	3,993,300,000	3,308,500,000	106,700,000	68,200,000	3,842,800,000	3,218,600,000	43,800,000	21,700,000									6,849,400,000	5,690,900,000	454,200,000	642,500,000	6,262,900,000	4,965,300,000	132,300,000	83,100,000
Liabilities of consolidated investment entities			7,507,700,000	6,064,900,000	723,000,000	435,300,000							723,000,000	435,300,000							6,784,700,000	5,629,600,000							6,344,400,000	5,161,600,000	440,300,000	468,000,000
Default of Collateral Assets, Percentage																																			1.00%	1.00%
Debt Instrument, Description of Variable Rate Basis	LIBOR																		EURIBOR																		LIBOR
Utilization	$ 5,674,400,000														$ 273,000,000	$ 212,200,000																		$ 60,000,000