Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Consolidated Legg Mason, Inc.	Consolidated Legg Mason, Inc. COMMON STOCK	Consolidated Legg Mason, Inc. ADDITIONAL PAID-IN CAPITAL	Consolidated Legg Mason, Inc. EMPLOYEE STOCK TRUST	Consolidated Legg Mason, Inc. DEFERRED COMPENSATION EMPLOYEE STOCK TRUST	Consolidated Legg Mason, Inc. RETAINED EARNINGS, UNAPPROPRIATED	Consolidated Legg Mason, Inc. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), NET	Consolidated Investment Vehicles [Member]
Beginning Balance at Mar. 31, 2014			$ 11,717	$ 3,148,396	$ (29,922)	$ 29,922	$ 1,526,662	$ 37,949
Stock options exercised			25	7,622
Deferred compensation employee stock trust			2	1,139
Stock-based compensation			99	12,070
Adjustments to Additional Paid in Capital, Other				0
Employee tax withholdings by settlement of net share transactions			(45)	(20,851)
Shares repurchased and retired	$ (89,999)		(187)	(89,812)
Shares Issued to plans					(1,141)	1,141
Distributions and forfeitures					231	(231)
Net Income Attributable to Legg Mason, Inc.		$ 72,188					72,188		$ 1,736
Dividends declared							(19,191)
RE Reclassified for MEP Amortization							0
Net unrealized gain on reverse treasury rate lock								773
Reclassification for assets held for sale								(114)
Foreign currency translation adjustment		10,716						10,716
Ending Balance at Jun. 30, 2014		4,699,158	11,611	3,058,564	(30,832)	30,832	1,579,659	49,324
Beginning Balance at Mar. 31, 2015		4,484,901	11,147	2,844,441	(29,570)	29,570	1,690,055	(60,742)
Stock options exercised			16	5,014
Deferred compensation employee stock trust			0	111
Stock-based compensation			15	18,555
Adjustments to Additional Paid in Capital, Other				9,134
Employee tax withholdings by settlement of net share transactions			(39)	(20,963)
Shares repurchased and retired	$ (68,000)		(126)	(67,874)
Shares Issued to plans					(111)	111
Distributions and forfeitures					0	0
Net Income Attributable to Legg Mason, Inc.		94,548					94,548		$ 302
Dividends declared							(22,338)
RE Reclassified for MEP Amortization							(480)
Net actuarial gain on defined benefit pension plan								1,068
Reclassification for assets held for sale								0
Foreign currency translation adjustment		20,664						20,664
Ending Balance at Jun. 30, 2015		$ 4,522,206	$ 11,013	$ 2,788,418	$ (29,681)	$ 29,681	$ 1,761,785	$ (39,010)