Investments of Operating Entities and Consolidated Funds - Real Estate Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Investment Holdings [Line Items]
Other investments	$ 70,151	$ 59,943
Operating Entities [Member]
Investment Holdings [Line Items]
Other investments	70,151	59,943
Operating Entities [Member] | Real Estate Investments [Member]
Investment Holdings [Line Items]
Other investments	2,102	2,353
RCG RE Manager, LLC [Member] | Operating Entities [Member] | Real Estate Equity Investment [Member]
Investment Holdings [Line Items]
Other investments	1,800	1,600
RCG RE Manager, LLC [Member] | Operating Entities [Member] | Real Estate Debt Investment [Member]
Investment Holdings [Line Items]
Other investments	$ 300	$ 800