Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows From Operating Activities
Net Income	$ 72,022	$ 39,479	$ 10,531
Adjustments to Reconcile Net Income to Net Cash Provided by Operating Activities:
Net (Gains) Losses on Investments, Marketable Securities and Contingent Consideration	(2,172)	756	(4,069)
Equity Method Investments	(1,454)	(2,672)	(919)
Equity-Based and Other Deferred Compensation	121,608	115,632	94,253
Depreciation, Amortization and Accretion	16,699	18,784	20,401
Bad Debt Expense	2,099	1,803	1,558
Adjustment to Tax Receivable Agreements	(6,905)	0	0
Deferred Taxes	20,058	(7,967)	11,026
Decrease (Increase) in Operating Assets:
Marketable Securities	234	674	461
Financial Instruments Owned and Pledged as Collateral at Fair Value	65,045	16,056	(91,056)
Securities Purchased Under Agreements to Resell	(19,578)	2,278	123,559
Accounts Receivable	1,460	(37,111)	2,749
Receivable from Employees and Related Parties	(4,542)	2,627	(4,275)
Other Assets	(19,945)	15,485	(144)
(Decrease) Increase in Operating Liabilities:
Accrued Compensation and Benefits	12,435	2,967	32,128
Accounts Payable and Accrued Expenses	258	466	1,499
Securities Sold Under Agreements to Repurchase	(45,543)	(18,413)	(32,283)
Payables to Employees and Related Parties	4,451	(2,429)	(7,067)
Taxes Payable	(15,591)	13,694	(1,777)
Other Liabilities	(1,925)	(1,951)	(8,739)
Net Cash Provided by Operating Activities	198,714	160,158	147,836
Cash Flows From Investing Activities
Investments Purchased	(3,012)	(2,161)	(48,575)
Distributions of Private Equity Investments	1,300	1,192	1,211
Marketable Securities:
Proceeds from Sales and Maturities	31,106	67,958	80,678
Purchases	(35,187)	(23,499)	(71,599)
Cash Paid for Acquisitions, net of Cash Acquired	218	(6,743)	(30,397)
Proceeds from Sale of Business	1,198	0	0
Change in Restricted Cash	0	2,111	0
Purchase of Furniture, Equipment and Leasehold Improvements	(4,487)	(13,941)	(8,662)
Net Cash Provided by (Used In) Investing Activities	(8,864)	24,917	(77,344)
Cash Flows From Financing Activities
Payments for Settlement of Debt and Capital Lease Obligations	0	(1,047)	(8,335)
Issuance of Noncontrolling Interests	3,589	469	1,009
Distributions to Noncontrolling Interests	(18,950)	(16,528)	(19,087)
Payments Under Tax Receivable Agreement	(7,651)	0	0
Cash Paid for Deferred and Contingent Consideration	(3,396)	(3,000)	(13,486)
Proceeds from Equity Offering, Net of Direct Expenses	0	0	168,140
Purchase of Treasury Stock and Noncontrolling Interests	(102,277)	(66,983)	(140,242)
Excess Tax Benefits Associated with Equity-Based Awards	8,979	1,451	6,266
Dividends - Class A Stockholders	(30,090)	(24,296)	(19,346)
Other	0	(78)	0
Net Cash Provided by (Used in) Financing Activities	(149,796)	(110,012)	(25,081)
Effect of Exchange Rate Changes on Cash	(1,032)	1,463	(3,843)
Net Increase in Cash and Cash Equivalents	39,022	76,526	41,568
Cash and Cash Equivalents-Beginning of Period	259,431	182,905	141,337
Cash and Cash Equivalents-End of Period	298,453	259,431	182,905
SUPPLEMENTAL CASH FLOW DISCLOSURE
Payments for Interest	12,807	13,962	17,914
Payments for Income Taxes	57,178	9,569	13,957
Furniture, Equipment and Leasehold Improvements Accrued	1,060	267	1,293
Increase (Decrease) in Fair Value of Redeemable Noncontrolling Interest	(12,985)	27,376	(3,942)
Dividend Equivalents Issued	5,989	4,969	2,805
Notes Exchanged for Equity in Subsidiary	1,042	0	0
Settlement of Contingent Consideration	2,494	0	0
Receipt of Marketable Securities in Settlement of Accounts Receivable	$ 2,728	$ 0	$ 0