Variable Interest Entities and Consolidation of Investment Vehicles (Details 8) (CIVs, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Estimate of Fair Value, Fair Value Disclosure	Mar. 31, 2012 Estimate of Fair Value, Fair Value Disclosure
Debt Instrument
Fair Value Option, Gain (Loss) recognized in other non-operating income of CIVs	$ (5,535)	$ 7,277	$ (8,958)	$ 2,726
Pre-defined interest rate spread of CLO debt, high end of range (as a percent)	4.00%		4.00%		4.00%		4.00%
Pre-defined interest rate spread of CLO debt, low end of range (as a percent)	0.25%		0.25%		0.25%		0.25%
Derivative liabilities									(3,237)	(3,872)
Gain on Derivative Assets and Liabilities Recorded in Other Non-Operating Income of Consolidated Investment Vehicles					277	491	635	54,477
Loss on Derivative Assets and Liabilities Recorded in Other Non-Operating Income of Consolidated Investment Vehicles					$ (307)	$ (552)	$ (911)	$ (47,388)