Unconsolidated VIE's (Details 9) - USD ($) $ in Thousands		Sep. 30, 2017	Mar. 31, 2017
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	[1]	$ 58,026	$ 58,723
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[2]	76,435	89,473
Assets Under Management		29,159,845	26,735,285
Real Estate Investment Trusts [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	[1]	12,160	11,660
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[2]	13,968	15,763
Other sponsored investments fund [Member]
Variable Interest Entity
Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net	[1]	45,866	47,063
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	[2]	$ 62,467	$ 73,710

[1] Amounts are related to investments in proprietary and other fund products.

[2] Includes equity investments the Company has made or is required to make and any earned but uncollected management fees.