Earnings Per Share (Tables)

3 Months Ended

9 Months Ended

Dec. 31, 2011

Dec. 31, 2011

Earnings Per Share, Basic and Diluted [Abstract]

Computations of basic and diluted EPS

	Three Months Ended December 31,
	2011				2010
	Basic		Diluted		Basic			Diluted
Weighted-average basic shares outstanding	140,053		140,053		149,980			149,980
Potential common shares:
Employee stock options	—		29		—			231
Shares related to deferred compensation	—		—		—			761
Total weighted-average diluted shares	140,053		140,082		149,980			150,972
Net Income	$	35,141	$	35,141	$	53,364		$	53,364
Less: Net income (loss) attributable to noncontrolling interests	7,009		7,009		(8,256		)	(8,256		)
Net Income Attributable to Legg Mason, Inc.	$	28,132	$	28,132	$	61,620		$	61,620
Net Income per Share Attributable to  Legg Mason, Inc. Common Shareholders	$	0.20	$	0.20	$	0.41		$	0.41

	Nine Months Ended December 31,
	2011				2010
	Basic		Diluted		Basic			Diluted
Weighted-average basic shares outstanding	144,363		144,363		153,817			153,817
Potential common shares:
Employee stock options	—		65		—			200
Shares related to deferred compensation	—		—		—			531
Total weighted-average diluted shares	144,363		144,428		153,817			154,548
Net Income	$	154,222	$	154,222	$	174,995		$	174,995
Less: Net income (loss) attributable to noncontrolling interests	9,474		9,474		(9,891		)	(9,891		)
Net Income Attributable to Legg Mason, Inc.	$	144,748	$	144,748	$	184,886		$	184,886
Net Income per Share Attributable to  Legg Mason, Inc. Common Shareholders	$	1.00	$	1.00	$	1.20		$	1.20