Fair Value Measurement - Quantitative Information About Partnership's Level III Inputs (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified																																										12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Equity Securities [Member] Comparable Multiple 1 [Member]	Dec. 31, 2012 Equity Securities [Member] Comparable Multiple 2 [Member]	Dec. 31, 2012 Equity Securities [Member] Comparable Multiple 3 [Member]	Dec. 31, 2012 Equity Securities [Member] Consensus Pricing [Member]	Dec. 31, 2012 Equity Securities [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Loans [Member] Consensus Pricing [Member]	Dec. 31, 2012 Loans [Member] Market Yield Analysis [Member]	Dec. 31, 2012 Bond [Member] Consensus Pricing [Member]	Dec. 31, 2012 Partnerships and LLC interests [Member] Nav Of Underlying Fund [Member]	Dec. 31, 2012 Other [Member] Counterparty Pricing [Member]	Dec. 31, 2012 Trading securities and other [Member] Comparable Multiple 1 [Member]	Dec. 31, 2012 Trading securities and other [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Trading securities and other [Member] Dealer Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Market Yield Analysis [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities [Member] Comparable Multiple 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities [Member] Comparable Multiple 2 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities [Member] Comparable Multiple 3 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities [Member] Consensus Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Equity Securities [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Loans [Member] Consensus Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Bond [Member] Consensus Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Partnerships and LLC interests [Member] Nav Of Underlying Fund [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Other [Member] Counterparty Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Trading securities and other [Member] Comparable Multiple 1 [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Trading securities and other [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Trading securities and other [Member] Dealer Pricing [Member]	Dec. 31, 2012 Fair Value, Inputs, Level 3 [Member] Investments Of Consolidated Funds [Member]	Dec. 31, 2012 Contingent Consideration [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Contingent Consideration [Member] Fair Value, Inputs, Level 3 [Member] Discounted Cash Flow [Member]	Dec. 31, 2012 Senior Secured Notes [Member] Discounted Cash Flow With Consensus Pricing [Member]	Dec. 31, 2012 Senior Secured Notes [Member] Fair Value, Inputs, Level 3 [Member] Discounted Cash Flow With Consensus Pricing [Member]	Dec. 31, 2012 Subordinated Debt Obligations [Member] Discounted Cash Flow With Consensus Pricing [Member]	Dec. 31, 2012 Subordinated Debt Obligations [Member] Fair Value, Inputs, Level 3 [Member] Discounted Cash Flow With Consensus Pricing [Member]	Dec. 31, 2012 Combination Notes [Member] Consensus Pricing [Member]	Dec. 31, 2012 Combination Notes [Member] Fair Value, Inputs, Level 3 [Member] Consensus Pricing [Member]	Dec. 31, 2012 Derivative Financial Instruments, Liabilities [Member] Counterparty Pricing [Member]	Dec. 31, 2012 Derivative Financial Instruments, Liabilities [Member] Fair Value, Inputs, Level 3 [Member] Counterparty Pricing [Member]	Dec. 31, 2012 Minimum [Member] Fair Value, Inputs, Level 3 [Member] Equity Securities [Member]	Dec. 31, 2012 Minimum [Member] Fair Value, Inputs, Level 3 [Member] Loans [Member]	Dec. 31, 2012 Minimum [Member] Contingent Consideration [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Maximum [Member] Fair Value, Inputs, Level 3 [Member] Equity Securities [Member]	Dec. 31, 2012 Maximum [Member] Fair Value, Inputs, Level 3 [Member] Loans [Member]	Dec. 31, 2012 Maximum [Member] Contingent Consideration [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2012 Weighted Average [Member] Equity Securities [Member] Multiplier	Dec. 31, 2012 Weighted Average [Member] Loans [Member]	Dec. 31, 2012 Weighted Average [Member] Bond [Member]	Dec. 31, 2012 Weighted Average [Member] Other [Member]	Dec. 31, 2012 Weighted Average [Member] Trading securities and other [Member] Multiplier	Dec. 31, 2012 Weighted Average [Member] Contingent Consideration [Member]	Dec. 31, 2012 Weighted Average [Member] Senior Secured Notes [Member]	Dec. 31, 2012 Weighted Average [Member] Subordinated Debt Obligations [Member]	Dec. 31, 2012 Weighted Average [Member] Combination Notes [Member]	Dec. 31, 2012 Weighted Average [Member] Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of assets																$ 21,042.2		$ 337.2	$ 2,311.5	$ 69.4	$ 15.4	$ 33.8	$ 45.0	$ 12,952.9	$ 934.2	$ 4,315.5	$ 7.3	$ 6.2	$ 2.6	$ 11.2	$ 21,022.2
Indicative Quotes Range Notional Amount																																																			3.00%						6.00%
Assumed Range Percentage of Total Potential Contingent Payments																																												32.00%			10.00%						79.00%
Liabilities
Fair value of liabilities	244.3	169.2														186.7	169.2																								15.8
Fair value of liabilities	$ 13,927.3	$ 10,128.9														$ 13,859.2	$ 10,121.6																$ 186.7		$ 12,658.4		$ 996.9		$ 1.4
Indicative Quotes Range Percentage																																																	94.00%	94.00%		83.00%		93.00%	42.00%	96.00%
Recovery Rates Range Percentage																																																						58.00%	53.00%
Default Rates Range Percentage																																																						3.00%	3.00%
Discount Rate Range Percentage																																										9.00%		2.00%	15.00%		35.00%	11.00%				7.00%	17.00%	4.00%	29.00%
Indicative Quotes Per Share																																																$ 10
Book Value Multiple Range																																																1
LTM EBITDA Multiple Range																																										5.6			13.5			9.7				5.6
Price Earnings Multiple Range																																																13.5
Exit Cap Rate Range Percentage																																										6.00%			8.00%			7.00%
Market Yield Range Percentage																																											7.00%			18.00%			10.00%
Fair Value Measurements Valuation Technique of Liabilities			Comparable Multiple	Comparable Multiple	Comparable Multiple	Consensus Pricing	Discounted Cash Flow	Consensus Pricing	Market Yield Analysis	Consensus Pricing	NAV of Underlying Fund	Counterparty Pricing	Comparable Multiple	Discounted Cash Flow	Dealer Pricing																	Discounted Cash Flow		Discounted Cash Flow with Consensus Pricing		Discounted Cash Flow with Consensus Pricing		Consensus Pricing		Counterparty Pricing