Noncontrolling Interests Rollforward (Details) - USD ($) $ in Thousands		6 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015	Mar. 31, 2014
CIVs and Other
Noncontrolling Interest [Line Items]
REDEEMABLE NONCONTROLLING INTERESTS	[1]	$ 70,630	$ 45,633	$ 38,498	$ 43,328
Net Income (Loss) Attributable to Noncontrolling Interest	[1]	(1,009)	1,548
Net subscriptions received from noncontrolling interests	[1]	33,141	757
RE Reclassified for MEP Amortization	[1]	0
Management Equity Plan [Member]
Noncontrolling Interest [Line Items]
REDEEMABLE NONCONTROLLING INTERESTS		7,848	1,816	7,022	1,816
Net Income (Loss) Attributable to Noncontrolling Interest		0	0
Net subscriptions received from noncontrolling interests		0	0
RE Reclassified for MEP Amortization		826
Consolidated Legg Mason, Inc.
Noncontrolling Interest [Line Items]
REDEEMABLE NONCONTROLLING INTERESTS		78,478	47,449	$ 45,520	$ 45,144
Net Income (Loss) Attributable to Noncontrolling Interest		(1,009)	1,548
Net subscriptions received from noncontrolling interests		33,141	$ 757
RE Reclassified for MEP Amortization		$ 826

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