Related Parties (Schedule Of Payable To Employees And Related Parties) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Related Parties [Abstract]
Board of Director Fees	$ 235		$ 205
Lexicon Deferred Consideration Payable	358
Amounts Due to Former Members of Lexicon	5,844
Amounts Due Pursuant to Tax Receivable Agreements	6,210	[1]	3,976	[1]
Payable to Employees and Related Parties	12,647		4,181
Amounts Due Pursuant to Tax Receivable Agreements	$ 137,448		$ 97,427

[1] Relates to the current portion of the Member exchange of LP Units for Class A Shares. The long-term portion of $137,448 and $97,427 is disclosed in Amounts Due Pursuant to Tax Receivable Agreements on the Consolidated Statements of Financial Condition at December 31, 2011 and 2010, respectively.