Investments of Operating Entities and Consolidated Funds - Lehman Claims (Details) (USD $)	1 Months Ended
	Feb. 29, 2012	Dec. 31, 2011	Jul. 31, 2010	Jun. 30, 2010	Dec. 31, 2012	Nov. 30, 2012	Nov. 02, 2012	Sep. 15, 2008
Investment Holdings [Line Items]
Other investments		$ 59,943,000			$ 84,930,000
Operating Entities
Investment Holdings [Line Items]
Other investments		59,943,000			84,930,000
Operating Entities | Lehman Claim
Investment Holdings [Line Items]
Initial value								1,000,000
Claim settlement receivable					900,000		900,000
Dividend percent received						25.20%
Dividend amount received						200,000
Estimated recoverable percent		47.00%
Other investments		553,000			706,000
Consolidated Funds
Investment Holdings [Line Items]
Other investments		228,820,000			204,205,000
Consolidated Funds | Lehman Claim
Investment Holdings [Line Items]
Other investments		7,340,000			14,124,000
Enterprise Master [Member] | Lehman Claim
Investment Holdings [Line Items]
Initial value					12,400,000			24,300,000
Claim settlement receivable							1,300,000
Percent of client's Best Claim					90.00%
Value of Best Claim					12,100,000
Dividend percent received						25.20%
Dividend amount received						300,000
Assets returned		2,400,000		9,500,000
Proceeds from sale of returned assets			10,700,000
Distributions of proceeds from returned assets	2,900,000
Other Investments, claim to trust assets held by LBIE through Lehman Brothers					10,600,000
Other Investments, intial claim current value					17,700,000
Recoverable claims assigned to variable interest entities					100.00%
Enterprise Master [Member] | Trust Assets [Member]
Investment Holdings [Line Items]
Claim Resolution Agreement fee					1.00%
Enterprise Master [Member] | Foreign Denominated Assets [Member]
Investment Holdings [Line Items]
Claim Resolution Agreement fee					1.00%
Other Investments, not within control of LBIE					4,900,000
Enterprise Master [Member] | Cash [Member]
Investment Holdings [Line Items]
Initial value					5,300,000
Estimated recoverable percent					80.00%
Other investments					4,200,000
Enterprise LP [Member] | Lehman Claim
Investment Holdings [Line Items]
Other investments					$ 14,100,000