Fair Value Measurements for Operating Entities and Consolidated Funds - Fair Value Inputs, Unobservable Inputs, Quantitative Information (Details) (Operating Companies [Member], Level 3 [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	8,058
Assets and liabilities at fair value	225,035
Other Assets and Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets and liabilities at fair value	216,977	[1]
Income Approach and Market Approach Valuation Techniques [Member] | Common Stocks [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	2,960
Income Approach and Market Approach Valuation Techniques [Member] | Common Stocks [Member] | Minimum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Valuation Metric	25.00%
DCF Discount Rate	15.00%
Market Multiple	9
Income Approach and Market Approach Valuation Techniques [Member] | Common Stocks [Member] | Maximum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Valuation Metric	100.00%
DCF Discount Rate	25.00%
Market Multiple	10
Income Approach and Market Approach Valuation Techniques [Member] | Lehman Claim [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	761
DCF Discount Rate	15.00%
Projected Cash Flow Timing	9 months
Market Approach Valuation Technique [Member] | Warrants and Rights [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	4,062
Market Approach Valuation Technique [Member] | Warrants and Rights [Member] | Minimum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	20.00%
Market Approach Valuation Technique [Member] | Warrants and Rights [Member] | Maximum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	40.00%
Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Real Estate [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	275
Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Real Estate [Member] | Minimum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Capital Rate	4.99%
Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Real Estate [Member] | Maximum [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Capital Rate	8.75%

[1] Quantitative disclosures of unobservable inputs and assumptions are not required for investments for which NAV per share is used as a practical expedient to determine fair value, as their redemption features rather than observability of inputs cause them to be classified as a level 3 type asset within the fair value hierarchy. In addition, the fair value of the Consolidated Funds' investments are determined based on net asset value and therefore quantitative disclosures are not included in the table above.