Significant Accounting Policies (Details 2) (Legg Mason, Inc., USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Legg Mason, Inc.
Noncontrolling Interests Redeemable
Balance, beginning of period	$ 36,712	$ 29,577
Net income attributable to redeemable noncontrolling interests	8,120	1,941
Net subscriptions received from (redemptions/distributions paid to) noncontrolling interest holders	(16,016)	776
Balance, end of period	$ 28,816	$ 32,294