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	6 Months Ended
	Jun. 30, 2012
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	$ 4,808
Assets and liabilities at fair value	242,531
Other Assets and Liabilities [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets and liabilities at fair value	237,723	[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	959
DCF Discount Rate	25.00%
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%
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%
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	731
DCF Discount Rate	15.00%
Projected Cash Flow Timing	1 year
Market Approach Valuation Technique [Member] | Warrants and Rights [Member]
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investments at fair value	2,841
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	$ 277
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	4.74%
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.