Earnings Per Share (Tables)

3 Months Ended

6 Months Ended

Sep. 30, 2011

Sep. 30, 2011

Earnings Per Share, Basic and Diluted [Abstract]

Computations of basic and diluted EPS

	Three Months Ended September 30,
	2011				2010
	Basic		Diluted		Basic		Diluted
Weighted-average basic shares outstanding	143,877		143,877		151,416		151,416
Potential common shares:
Employee stock options	—		54		—		111
Shares related to deferred compensation	—		—		—		413
Total weighted-average diluted shares	143,877		143,931		151,416		151,940
Net Income	$	57,383	$	57,383	$	76,588	$	76,588
Less: Net income attributable to noncontrolling interests	719		719		1,253		1,253
Net Income Attributable to Legg Mason, Inc.	$	56,664	$	56,664	$	75,335	$	75,335
Net Income per Share Attributable to  Legg Mason, Inc. Common Shareholders	$	0.39	$	0.39	$	0.50	$	0.50

	Six Months Ended September 30,
	2011				2010
	Basic		Diluted		Basic			Diluted
Weighted-average basic shares outstanding	146,529		146,529		155,746			155,746
Potential common shares:
Employee stock options	—		96		—			143
Shares related to deferred compensation	—		—		—			438
Total weighted-average diluted shares	146,529		146,625		155,746			156,327
Net Income	$	119,081	$	119,081	$	121,631		$	121,631
Less: Net income (loss) attributable to noncontrolling interests	2,465		2,465		(1,635		)	(1,635		)
Net Income Attributable to Legg Mason, Inc.	$	116,616	$	116,616	$	123,266		$	123,266
Net Income per Share Attributable to  Legg Mason, Inc. Common Shareholders	$	0.80	$	0.80	$	0.79		$	0.79