Noncontrolling Interests Rollforward (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2016		Dec. 31, 2015	May 02, 2016	Mar. 31, 2016		Mar. 31, 2015
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		$ 696,800		$ 158,531	$ 696,800		$ 158,531		$ 175,785		$ 45,520
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest		11,063		16	39,335		(993)
Proceeds from (Payments to) Noncontrolling Interests					(18,310)		50,571
APIC reclassified for MEP vesting							2,489
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(18,797)		(691)
Noncontrolling Interest, Increase from Business Combination							61,067
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		510,500			510,500
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(4,094)		568
RE Reclassified for MEP Amortization					6,261
CIVs and Other
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount	[1]	81,375		84,578	81,375		84,578		94,136		36,549
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest	[1]				8,153		(2,542)
Proceeds from (Payments to) Noncontrolling Interests	[1]				(20,914)	[2]	50,571
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					0
Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		590,317		64,442	590,317		64,442		68,922
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					31,182
Proceeds from (Payments to) Noncontrolling Interests					2,604
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(18,797)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		510,500			510,500
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(4,094)
Management Equity Plan [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		25,108		9,511	25,108		9,511		12,727		$ 7,022
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					0		0
Proceeds from (Payments to) Noncontrolling Interests					6,120		0
APIC reclassified for MEP vesting							2,489
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					0
RE Reclassified for MEP Amortization					6,261
EnTrustPermal [Member]
Noncontrolling Interest [Line Items]
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value								$ 403,200
EnTrustPermal [Member] | Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		407,444			407,444				0
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					17,099
Proceeds from (Payments to) Noncontrolling Interests					0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(12,855)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		403,200			403,200
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					0
Clarion Partners [Member] | Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		111,406			111,406				0
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					8,839
Proceeds from (Payments to) Noncontrolling Interests					0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(2,733)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		105,300			105,300
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					0
RARE Infrastructure, Ltd [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Increase from Business Combination							61,067
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange							568
RARE Infrastructure, Ltd [Member] | Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		65,089			65,089				67,155
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					4,731
Proceeds from (Payments to) Noncontrolling Interests					0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(2,703)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		0			0
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					(4,094)
Royce [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest		2,025		0	5,732		0
Management Equity Plan [Member] | Royce [Member]
Noncontrolling Interest [Line Items]
Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest					5,732		0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(4,555)	[3]	0
Stockholders' Equity Attributable to Noncontrolling Interest		23,379	[3]	$ 0	23,379	[3]	$ 0		22,202	[3]
Other Affiliates [Member] | Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Redeemable Noncontrolling Interest, Equity, Carrying Amount		6,378			6,378				$ 1,767
Net Income (Loss) Attributable to Redeemable Noncontrolling Interest					513
Proceeds from (Payments to) Noncontrolling Interests					2,604
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders					(506)
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		$ 2,000			2,000
Noncontrolling Interest, Period Increase (Decrease), Foreign Exchange					$ 0

[1] Principally related to VIE and seeded investment products.

[2] Includes the impact related to the adoption of updated consolidation accounting guidance further discussed in Note 2.

[3] Related to Royce management equity plan.