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	3 Months Ended
	Mar. 31, 2013
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	8,510
Assets and liabilities at fair value	229,441
Other Assets and Liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets and liabilities at fair value	220,931	[1]
Lehman Claim
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	660
Income Approach and Market Approach Valuation Techniques | Common and Preferred Stock
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	4,610
Income Approach and Market Approach Valuation Techniques | Common and Preferred Stock | 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 | Common and Preferred Stock | 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 | 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 | Lehman Claim | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
DCF discount rate	15.00%
Market Approach Valuation Technique | Warrants and Rights
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	3,240
Market Approach Valuation Technique | Warrants and Rights | Minimum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	20.00%
Market Approach Valuation Technique | Warrants and Rights | Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	150.00%

[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.