VIE Consolidated Balance Sheet Detail (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Variable Interest Entity
REDEEMABLE NONCONTROLLING INTERESTS		$ 696,800	$ 175,785	$ 158,531	$ 45,520
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity
Current Assets	[1]	105,101	110,631
Non-current Assets	[1]	9,998	84
TOTAL ASSETS	[1]	115,099	110,715
Current Liabilities	[1]	2,059	4,548
Non-current Liabilities	[1]	0	0
TOTAL LIABILITIES	[1]	2,059	4,548
REDEEMABLE NONCONTROLLING INTERESTS	[1]	24,016	94,027
Total Stockholders' Equity	[1]	89,024	12,140
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	[1]	115,099	110,715
Consolidated Legg Mason, Inc.
Variable Interest Entity
Current Assets		1,768,026	2,385,044
Non-current Assets		6,491,846	5,135,402
TOTAL ASSETS		8,259,872	7,520,446
Current Liabilities		747,369	841,553
Non-current Liabilities		2,814,838	2,267,343
TOTAL LIABILITIES		3,562,207	3,108,896
REDEEMABLE NONCONTROLLING INTERESTS		696,800	175,785
Total Stockholders' Equity		4,000,865	4,235,765	$ 4,285,257
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		8,259,872	7,520,446
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Variable Interest Entity
Current Assets	[1]	1,691,997	2,288,080
Non-current Assets	[1]	6,484,583	5,135,318
TOTAL ASSETS	[1]	8,176,580	7,423,398
Current Liabilities	[1]	745,338	837,031
Non-current Liabilities	[1]	2,814,838	2,267,343
TOTAL LIABILITIES	[1]	3,560,176	3,104,374
REDEEMABLE NONCONTROLLING INTERESTS	[1]	615,425	81,649
Total Stockholders' Equity	[1]	4,000,979	4,237,375
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	[1]	8,176,580	7,423,398
Consolidation, Eliminations [Member]
Variable Interest Entity
Current Assets		(29,072)	(13,667)
Non-current Assets		(2,735)	0
TOTAL ASSETS		(31,807)	(13,667)
Current Liabilities		(28)	(26)
Non-current Liabilities		0	0
TOTAL LIABILITIES		(28)	(26)
REDEEMABLE NONCONTROLLING INTERESTS		57,359	109
Total Stockholders' Equity		(89,138)	(13,750)
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY		$ (31,807)	$ (13,667)

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