CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Consolidated Legg Mason Group [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Consolidated Legg Mason Group [Member]
Net Income	$ 35,141	$ 53,364	$ 154,222	$ 174,995
Other comprehensive income:
Foreign currency translation adjustment	3,309	7,760	(29,357)	27,733
Unrealized gains (losses) on investment securities:
Unrealized holding gains (losses), net of tax provision of ($2), $(54), $167 and $3, respectively	(3)	(80)	250	4
Reclassification adjustment for losses (gains) included in net income	4	3	8	0
Net unrealized gains on investment securities	1	(77)	258	4
Total other comprehensive income (loss)	3,310	7,683	(29,099)	27,737
COMPREHENSIVE INCOME	38,451	61,047	125,123	202,732
Less: Comprehensive income (loss) attributable to noncontrolling interests	7,009	(8,256)	9,474	(9,891)
COMPREHENSIVE INCOME ATTRIBUTABLE TO LEGG MASON, INC.	$ 31,442	$ 69,303	$ 115,649	$ 212,623