VIE Consolidated Balance Sheet Detail (Details) - USD ($) $ in Thousands		Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016
Variable Interest Entity
REDEEMABLE NONCONTROLLING INTERESTS		$ 684,203	$ 677,772	$ 722,562	$ 175,785
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity
Current Assets	[1]	97,091	77,406
Non-current Assets	[1]	9,968	9,987
TOTAL ASSETS	[1]	107,059	87,393
Current Liabilities	[1]	1,762	736
Non-current Liabilities	[1]	0	0
TOTAL LIABILITIES	[1]	1,762	736
REDEEMABLE NONCONTROLLING INTERESTS	[1]	12,691	26,853
Total Stockholders' Equity	[1]	92,606	59,804
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	[1]	107,059	87,393
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Variable Interest Entity
Current Assets	[1]	1,541,578	1,749,959
Non-current Assets	[1]	6,441,831	6,481,376
TOTAL ASSETS	[1]	7,983,409	8,231,335
Current Liabilities	[1]	584,635	808,664
Non-current Liabilities	[1]	2,789,069	2,792,084
TOTAL LIABILITIES	[1]	3,373,704	3,600,748
REDEEMABLE NONCONTROLLING INTERESTS	[1]	614,819	619,302
Total Stockholders' Equity	[1]	3,994,886	4,011,285
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	[1]	7,983,409	8,231,335
Consolidated Legg Mason, Inc.
Variable Interest Entity
Current Assets		1,605,601	1,801,747
Non-current Assets		6,448,828	6,488,668
TOTAL ASSETS		8,054,429	8,290,415
Current Liabilities		586,384	809,387
Non-current Liabilities		2,789,069	2,792,084
TOTAL LIABILITIES		3,375,453	3,601,471
REDEEMABLE NONCONTROLLING INTERESTS		684,203	677,772
Total Stockholders' Equity		3,994,773	4,011,172	$ 4,117,570
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		8,054,429	8,290,415
Consolidation, Eliminations [Member]
Variable Interest Entity
Current Assets		(33,068)	(25,618)
Non-current Assets		(2,971)	(2,695)
TOTAL ASSETS		(36,039)	(28,313)
Current Liabilities		(13)	(13)
Non-current Liabilities		0	0
TOTAL LIABILITIES		(13)	(13)
REDEEMABLE NONCONTROLLING INTERESTS		56,693	31,617
Total Stockholders' Equity		(92,719)	(59,917)
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		$ (36,039)	$ (28,313)

[1] Other represents consolidated sponsored investment products (VREs) that are not designated as CIVs.