Derivatives and Hedging Fair Value of Derivative Liabilities (Details) - Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member] - Not Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Sep. 30, 2016	Mar. 31, 2016
Derivative
Derivative Liability, Fair Value, Gross Liability	$ (6,916)	$ (16,364)
Derivative Liability, Fair Value, Gross Asset	3,499	280
Derivative Liability	(3,417)	(16,084)
Derivative Liability, Not Subject to Master Netting Arrangement	(2,327)	(1,995)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	7,291	5,920
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	1,547	(12,159)
Foreign Exchange Forward [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability	(6,916)	(16,364)
Derivative Liability, Fair Value, Gross Asset	3,499	280
Derivative Liability	(3,417)	(16,084)
Derivative Liability, Not Subject to Master Netting Arrangement	0	0
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	(3,417)	(16,084)
Future [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability	0
Derivative Liability, Fair Value, Gross Asset	0
Derivative Liability	0
Derivative Liability, Not Subject to Master Netting Arrangement	(2,327)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	7,291
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement	$ 4,964
Forward Contracts [Member]
Derivative
Derivative Liability, Fair Value, Gross Liability		0
Derivative Liability, Fair Value, Gross Asset		0
Derivative Liability		0
Derivative Liability, Not Subject to Master Netting Arrangement		(1,995)
Derivative Liability, Collateral, Right to Reclaim Cash, Offset		5,920
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		$ 3,925