Fair Value Measurements for Operating Entities and Consolidated Funds Fair Value Inputs, Unobservable Inputs, Quantitative Information (Details) (Operating Companies, Level 3, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	7,812
Assets and liabilities at fair value	232,390
Other Assets and Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets and liabilities at fair value	224,578	[1]
Income Approach and Market Approach Valuation Techniques [Member] | Common Stocks
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	4,881
Income Approach and Market Approach Valuation Techniques [Member] | Corporate Bonds
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	515
Income Approach and Market Approach Valuation Techniques [Member] | Common and Preferred Stock [Member] | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF Discount Rate	15.00%
Market Multiple	9
Income Approach and Market Approach Valuation Techniques [Member] | Common and Preferred Stock [Member] | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF Discount Rate	25.00%
Market Multiple	10
Income Approach and Market Approach Valuation Techniques [Member] | Lehman Claim | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF Discount Rate	0.00%
Income Approach and Market Approach Valuation Techniques [Member] | Lehman Claim | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF Discount Rate	15.00%
Market Approach Valuation Technique [Member] | Warrants and Rights
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	1,710
Market Approach Valuation Technique [Member] | Warrants and Rights | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	20.00%
Market Approach Valuation Technique [Member] | Warrants and Rights | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	40.00%
Market Approach, Income Approach and Replacement Cost Valuation Techniques [Member] | Corporate Bonds
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Liquidation discount	35.00%

[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.