CONSOLIDATED STATEMENTS OF INCOME (LOSS) (USD $) In Thousands, except Per Share data	12 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2009
Investment advisory fees
Separate accounts	$ 815,633	$ 814,824	$ 1,017,195
Funds	1,486,615	1,367,297	1,836,350
Performance fees	96,661	71,452	17,429
Distribution and service fees	379,161	375,333	475,003
Other	6,247	5,973	11,390
Total operating revenues	2,784,317	2,634,879	3,357,367
OPERATING EXPENSES
Compensation and benefits	1,140,305	1,111,298	1,132,216
Transition-related compensation	45,048
Total compensation and benefits	1,185,353	1,111,298	1,132,216
Distribution and servicing	712,839	691,931	969,964
Communications and technology	161,969	163,098	188,312
Occupancy	137,861	156,967	209,537
Amortization of intangible assets	22,913	22,769	36,488
Impairment of goodwill and intangible assets			1,307,970
Other	176,574	167,633	182,060
Total operating expenses	2,397,509	2,313,696	4,026,547
OPERATING INCOME (LOSS)	386,808	321,183	(669,180)
OTHER NON-OPERATING INCOME (EXPENSE)
Interest income	9,246	7,354	56,272
Interest expense	(92,157)	(126,273)	(182,805)
Fund support		23,171	(2,283,236)
Other	59,596	86,892	(117,044)
Other non-operating income of consolidated investment vehicles, net	1,704	17,329	7,796
Total other non-operating income (expense)	(21,611)	8,473	(2,519,017)
INCOME (LOSS) BEFORE INCOME TAX PROVISION (BENEFIT)	365,197	329,656	(3,188,197)
Income tax provision (benefit)	119,434	118,676	(1,223,203)
NET INCOME (LOSS)	245,763	210,980	(1,964,994)
Less: Net income (loss) attributable to noncontrolling interests	(8,160)	6,623	2,924
NET INCOME (LOSS) ATTRIBUTABLE TO LEGG MASON, INC.	$ 253,923	$ 204,357	$ (1,967,918)
NET INCOME (LOSS) PER SHARE ATTRIBUTABLE TO LEGG MASON, INC. COMMON SHAREHOLDERS
Basic (in dollars per share)	$ 1.63	$ 1.33	$ (13.99)
Diluted (in dollars per share)	$ 1.63	$ 1.32	$ (13.99)