Fair Value Measurements for Operating Entities and Consolidated Funds Assets and Liabilities at Fair Value on a Recurring Basis (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	$ 177,937	$ 334,251
Operating Companies | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	7,812
Operating Companies | Fair Value, Measurements, Recurring | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	682,797	788,977
Liabilities at fair value	178,910	335,008
Operating Companies | Fair Value, Measurements, Recurring | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	413,843	491,607
Liabilities at fair value	178,157	333,337
Operating Companies | Fair Value, Measurements, Recurring | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	233,605	274,942
Liabilities at fair value	750	1,671
Operating Companies | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	35,349	22,428
Liabilities at fair value	3	0
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	168,797	123,877
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	168,797	123,875
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0	2
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value		165,197
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value		165,197
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value		0
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value		0
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	61	1,529
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	61	1,529
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	3
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	0
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities sold, not yet purchased, at fair value	3
Operating Companies | Fair Value, Measurements, Recurring | Futures [Member] | Derivative Liabilities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	370	617
Operating Companies | Fair Value, Measurements, Recurring | Futures [Member] | Derivative Liabilities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	370	617
Operating Companies | Fair Value, Measurements, Recurring | Futures [Member] | Derivative Liabilities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Operating Companies | Fair Value, Measurements, Recurring | Futures [Member] | Derivative Liabilities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Operating Companies | Fair Value, Measurements, Recurring | Equity Swap [Member] | Derivative Liabilities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		140
Operating Companies | Fair Value, Measurements, Recurring | Equity Swap [Member] | Derivative Liabilities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0
Operating Companies | Fair Value, Measurements, Recurring | Equity Swap [Member] | Derivative Liabilities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		140
Operating Companies | Fair Value, Measurements, Recurring | Equity Swap [Member] | Derivative Liabilities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities		0
Operating Companies | Fair Value, Measurements, Recurring | Forward Contracts [Member] | Derivative Liabilities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	603
Operating Companies | Fair Value, Measurements, Recurring | Forward Contracts [Member] | Derivative Liabilities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0
Operating Companies | Fair Value, Measurements, Recurring | Forward Contracts [Member] | Derivative Liabilities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	603
Operating Companies | Fair Value, Measurements, Recurring | Forward Contracts [Member] | Derivative Liabilities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0
Operating Companies | Fair Value, Measurements, Recurring | Options [Member] | Derivative Liabilities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	9,076	43,648
Operating Companies | Fair Value, Measurements, Recurring | Options [Member] | Derivative Liabilities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	8,990	43,648
Operating Companies | Fair Value, Measurements, Recurring | Options [Member] | Derivative Liabilities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	86	0
Operating Companies | Fair Value, Measurements, Recurring | Options [Member] | Derivative Liabilities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Operating Companies | Fair Value, Measurements, Recurring | Preferred Stock | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,332
Operating Companies | Fair Value, Measurements, Recurring | Preferred Stock | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0
Operating Companies | Fair Value, Measurements, Recurring | Preferred Stock | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0
Operating Companies | Fair Value, Measurements, Recurring | Preferred Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,332	250	0
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	137,478	182,868
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	137,478	182,868
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Convertible Bonds [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	6,202	18,130
Operating Companies | Fair Value, Measurements, Recurring | Convertible Bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Convertible Bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	6,202	18,130
Operating Companies | Fair Value, Measurements, Recurring | Convertible Bonds [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	193,078	231,864
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	192,563	231,864
Operating Companies | Fair Value, Measurements, Recurring | Corporate Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	515	0	0
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	259,292	250,130
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	254,606	248,598
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,137	713
Operating Companies | Fair Value, Measurements, Recurring | Common Stock | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,549	819	334
Operating Companies | Fair Value, Measurements, Recurring | Mutual Funds [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,845	3,214
Operating Companies | Fair Value, Measurements, Recurring | Mutual Funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,845	3,214
Operating Companies | Fair Value, Measurements, Recurring | Mutual Funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Mutual Funds [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Futures [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		172
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Futures [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		172
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Futures [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Futures [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Equity Swap [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		635
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Equity Swap [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Equity Swap [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		635
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Equity Swap [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Forward Contracts [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	202
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Forward Contracts [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Forward Contracts [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	202
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Forward Contracts [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Options [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	20,546	55,699
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Options [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	18,273	55,530
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Options [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	2,273	169
Operating Companies | Fair Value, Measurements, Recurring | Derivative Assets | Options [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	2,354	2,759
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	641	1,225
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Warrants and Rights | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,713	1,534
Operating Companies | Fair Value, Measurements, Recurring | Portfolio Funds | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	55,898	40,350
Operating Companies | Fair Value, Measurements, Recurring | Portfolio Funds | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Portfolio Funds | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	30,228	23,431
Operating Companies | Fair Value, Measurements, Recurring | Portfolio Funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	25,670	16,919	17,081
Operating Companies | Fair Value, Measurements, Recurring | Real Estate Investments | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,864	2,353
Operating Companies | Fair Value, Measurements, Recurring | Real Estate Investments | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Real Estate Investments | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Real Estate Investments | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,864	2,353	1,882
Operating Companies | Fair Value, Measurements, Recurring | Lehman Claim | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	706	553
Operating Companies | Fair Value, Measurements, Recurring | Lehman Claim | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Lehman Claim | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Operating Companies | Fair Value, Measurements, Recurring | Lehman Claim | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	706	553	313
Consolidated Funds | Fair Value, Measurements, Recurring | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	207,730	235,154
Consolidated Funds | Fair Value, Measurements, Recurring | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	1,911	2,006
Consolidated Funds | Fair Value, Measurements, Recurring | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	8,775	12,406
Consolidated Funds | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets at fair value	197,044	220,742
Consolidated Funds | Fair Value, Measurements, Recurring | US Government Securities [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,911	2,006
Consolidated Funds | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,911	2,006
Consolidated Funds | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | US Government Securities [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Corporate Bonds | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value		401
Consolidated Funds | Fair Value, Measurements, Recurring | Corporate Bonds | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value		0
Consolidated Funds | Fair Value, Measurements, Recurring | Corporate Bonds | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value		401
Consolidated Funds | Fair Value, Measurements, Recurring | Corporate Bonds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value		0
Consolidated Funds | Fair Value, Measurements, Recurring | Commercial Paper [Member] | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,614	3,927
Consolidated Funds | Fair Value, Measurements, Recurring | Commercial Paper [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Commercial Paper [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	1,614	3,927
Consolidated Funds | Fair Value, Measurements, Recurring | Commercial Paper [Member] | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Portfolio Funds | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	190,081	221,480
Consolidated Funds | Fair Value, Measurements, Recurring | Portfolio Funds | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Portfolio Funds | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	7,161	8,078
Consolidated Funds | Fair Value, Measurements, Recurring | Portfolio Funds | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	182,920	213,402	311,242
Consolidated Funds | Fair Value, Measurements, Recurring | Lehman Claim | Total Estimated Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	14,124	7,340
Consolidated Funds | Fair Value, Measurements, Recurring | Lehman Claim | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Lehman Claim | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	0	0
Consolidated Funds | Fair Value, Measurements, Recurring | Lehman Claim | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments at fair value	$ 14,124	$ 7,340	$ 6,243