Variable Interest Entities and Consolidation of Investment Vehicles (Details 4) (CIVs, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2012
Minimum
Unobservable input subject to measurement uncertainty
Discount rate	1.10%	1.70%
Default rate	3.00%	2.50%
Maximum
Unobservable input subject to measurement uncertainty
Discount rate	11.00%	24.50%
Default rate	4.00%	4.00%
Weighted-average
Unobservable input subject to measurement uncertainty
Discount rate	2.30%	3.80%
Default rate	3.50%	3.40%
Constant prepayment rate	25.00%	15.00%
Significant unobservable inputs (Level 3)
Assets measured at fair value using significant unobservable inputs subject to measurement uncertainty
CLO debt	(207,835)	(271,707)