Variable Interest Entities and Consolidation of Investment Vehicles (Details 4) (CIVs, USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Mar. 31, 2013
Minimum
Unobservable input subject to measurement uncertainty
Discount rate	0.90%	1.10%
Default rate	3.00%	3.00%
Maximum
Unobservable input subject to measurement uncertainty
Discount rate	9.00%	11.00%
Default rate	4.00%	4.00%
Weighted-average
Unobservable input subject to measurement uncertainty
Discount rate	2.40%	2.30%
Default rate	3.50%	3.50%
Constant prepayment rate	25.00%	25.00%
Significant unobservable inputs (Level 3)
Assets measured at fair value using significant unobservable inputs subject to measurement uncertainty
CLO debt	$ (101,773)	$ (207,835)