Fair Value Measurements for Operating Entities and Consolidated Funds Carrying Value Disclosures (Details) (USD $)	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Cash and cash equivalents	$ 129,509,000		$ 54,720,000		$ 83,538,000	$ 128,875,000
Restricted Cash and Cash Equivalents	8,306,000		10,907,000
Securities borrowed	676,100,000		927,773,000
Cash and cash equivalents	501,000		2,048,000
Securities sold under agreement to repurchase	0		3,657,000
Securities loaned, Gross	682,493,000		918,577,000
Convertible debt	118,475,000	[1]	0
Note Payable	67,144,000		2,564,000
Convertible Debt
Convertible debt	118,475,000
Debt Instrument, Unamortized Premium	31,000,000
Level 1
Cash and Cash Equivalents, Fair Value Disclosure	129,509,000		54,720,000
Securities Borrowed, Fair Value Disclosure	660,445,000		892,792,000
Cash and cash Equivalents, Consolidated Funds, Fair Value Disclosure	501,000		2,048,000
Securities Loaned, Fair Value	661,533,000		881,690,000
Level 2
Restricted Cash fair Value Disclosure	8,306,000		10,907,000
Securities Loaned or Sold under Agreements to Repurchase, Fair Value Disclosure	0		3,657,000	[2]
Convertible Debt, Fair Value Disclosures	160,713,000	[3]	0
Long-term Debt, Fair Value	$ 69,548,000		$ 2,564,000

[1] The carrying amount of the convertible debt includes unamortized discount of $31.0 million.

[2] Transactions involving the purchase or sale of securities under repurchase/resell agreements are carried at their contract value, which approximates fair value, and are accounted for as collateralized financings.

[3] The Convertible Notes include the conversion option and is based on the last broker quote available.