CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (USD $) In Thousands	Total	COMMON STOCK	SHARES EXCHANGEABLE INTO COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	EMPLOYEE STOCK TRUST	DEFERRED COMPENSATION EMPLOYEE STOCK TRUST	RETAINED EARNINGS	APPROPRIATED RETAINED EARNINGS OF CONSOLIDATED INVESTMENT VEHICLES	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), NET
Balance at Mar. 31, 2008		$ 13,856	$ 4,982	$ 3,446,559	$ (29,307)	$ 29,307	$ 3,236,314		$ 82,930
Increase (Decrease) in Stockholders' Equity
Stock options and other stock-based compensation		109		37,988
Deferred compensation employee stock trust		16		6,505
Deferred compensation, net		92		33,107
Convertible debt				(73,430)
Exchangeable shares		76	(1,913)	1,837
Preferred share conversions		36		(36)
Shares issued to plans					(5,787)	5,787
Net income (loss) attributable to Legg Mason, Inc.	(1,967,918)						(1,967,918)
Dividends declared							(136,771)
Realized and unrealized holding gains (losses) on investment securities, net of tax	61								61
Unrealized and realized gains on cash flow hedge, net of tax	938								938
Foreign currency translation adjustment	(86,713)								(86,713)
Balance at Mar. 31, 2009	4,598,625	14,185	3,069	3,452,530	(35,094)	35,094	1,131,625		(2,784)
Increase (Decrease) in Stockholders' Equity
Stock options and other stock-based compensation		8		18,758
Deferred compensation employee stock trust		13		3,156
Deferred compensation, net		66		29,056
Exchangeable shares		12	(309)	297
Equity Units exchanged		1,860		943,815
Shares issued to plans					(2,938)	2,938
Distributions and forfeitures					4,937	(4,937)
Net income (loss) attributable to Legg Mason, Inc.	204,357						204,357
Dividends declared							(19,001)
Realized and unrealized holding gains (losses) on investment securities, net of tax	(18)								(18)
Foreign currency translation adjustment	61,029								61,029
Balance at Mar. 31, 2010	5,841,724	16,144	2,760	4,447,612	(33,095)	33,095	1,316,981		58,227
Increase (Decrease) in Stockholders' Equity
Stock options and other stock-based compensation		64		31,674
Deferred compensation employee stock trust		7		2,673
Deferred compensation, net		152		34,619
Exchangeable shares		110	(2,760)	2,650
Equity Units exchanged				35,877
Shares repurchased and retired		(1,455)		(444,010)
Shares issued to plans					(2,136)	2,136
Distributions and forfeitures					765	(765)
Cumulative effect of change in accounting principle								24,666
Net income (loss) attributable to Legg Mason, Inc.	253,923						253,923
Dividends declared							(30,920)
Net loss reclassified to Appropriated retained earnings								(13,744)
Realized and unrealized holding gains (losses) on investment securities, net of tax	(25)								(25)
Foreign currency translation adjustment	35,159								35,159
Balance at Mar. 31, 2011	$ 5,770,384	$ 15,022		$ 4,111,095	$ (34,466)	$ 34,466	$ 1,539,984	$ 10,922	$ 93,361