Changes in Level 3 Assets and Liabilities (Details 3) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unrealized Gains (Losses) Relating to Fair Value Measurements Using Unobservable Inputs Assets and Liabilities Still Held at Reporting Date	$ 4,040	$ 1,331
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value using significant unobservable inputs, value at beginning of period	63,118	84,839
Purchases	1,243	968
Sales	(6,177)	(5,858)
Redemptions/Settlements/Other	(4,960)	(564)
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	512	161
Assets measured at fair value using significant unobservable inputs, value at end of period	53,736	79,546
Proprietary Fund Product And Other Investments [Member] | Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value using significant unobservable inputs, value at beginning of period	186	190
Purchases	0	0
Sales	(7)	(10)
Redemptions/Settlements/Other	0	0
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	12	(1)
Assets measured at fair value using significant unobservable inputs, value at end of period	191	179
Investment In Partnerships And Limited Liability Companies [Member] | Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value using significant unobservable inputs, value at beginning of period	14,511	21,586
Purchases	0	0
Sales	0	0
Redemptions/Settlements/Other	(2,528)	0
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	(76)	68
Assets measured at fair value using significant unobservable inputs, value at end of period	11,907	21,654
Equity Method Investments In Partnerships And LLCs [Member] | Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value using significant unobservable inputs, value at beginning of period	48,344	62,973
Purchases	1,243	968
Sales	(6,170)	(5,848)
Redemptions/Settlements/Other	(2,432)	(564)
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	577	92
Assets measured at fair value using significant unobservable inputs, value at end of period	41,562	57,621
Other Investments [Member] | Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets measured at fair value using significant unobservable inputs, value at beginning of period	77	90
Purchases	0	0
Sales	0	0
Redemptions/Settlements/Other	0	0
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	(1)	2
Assets measured at fair value using significant unobservable inputs, value at end of period	76	92
Contingent Consideration Liability | Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Liabilities measured at fair value using significant unobservable inputs, value at beginning of period	(110,784)	(29,553)
Purchases	0	(14,670)
Sales	0	0
Redemptions/Settlements/Other	22,765	0
Transfers, Net	0	0
Realized and unrealized gains/(losses), net	(4,725)	(1,061)
Liabilities measured at fair value using significant unobservable inputs, value at end of period	$ (92,744)	$ (45,284)