Variable Interest Entities and Consolidation of Investment Vehicles (Details 8) (CIVs, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Estimate of Fair Value, Fair Value Disclosure	Mar. 31, 2012 Estimate of Fair Value, Fair Value Disclosure
Debt Instrument
Pre-defined interest rate spread of CLO debt, high end of range (as a percent)	4.00%
Pre-defined interest rate spread of CLO debt, low end of range (as a percent)	0.25%
Derivative liabilities			$ (3,620)	$ (3,872)
Gain on Derivative Assets and Liabilities Recorded in Other Non-Operating Income of Consolidated Investment Vehicles	252	12,090
Loss on Derivative Assets and Liabilities Recorded in Other Non-Operating Income of Consolidated Investment Vehicles	$ (299)	$ (11,811)