Investments and Fair Values of Assets and Liabilities (Details 4) (Legg Mason, Inc., USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013		Jun. 30, 2013
Funds-of-hedge funds
Nature of Investments
Fair Value Determined Using Nav	$ 38,811		$ 39,161	[1]
Percentage of Monthly Redemption (as a percent)	49.00%		49.00%
Percentage of Quarterly Redemption (as a percent)	51.00%		51.00%
Hedge funds
Nature of Investments
Fair Value Determined Using Nav	24,716		23,138
Unfunded Commitments			20,000
Private equity funds
Nature of Investments
Fair Value Determined Using Nav	23,763		22,982	[2]
Unfunded Commitments			5,043
Remaining term, high end of range (in years)	7
Other
Nature of Investments
Fair Value Determined Using Nav	2,408		2,116	[3]
Percentage of investment with less than 1 year remaining term (as a percent)	5.00%
Percentage of investment with 20-year remaining term (as a percent)	95.00%
Remaining term, low end of range (in years)	1
Remaining term, high end of range (in years)	20
Investments
Nature of Investments
Fair Value Determined Using Nav	89,698	[4]	87,397	[4]
Unfunded Commitments			$ 25,043
Assets valued using net asset value as practical expedient - Level 2	32.00%		33.00%
Assets at fair value using net asset as practical expedient - Level 3	68.00%		67.00%

[1] 49% monthly redemption; 51% quarterly redemption. Any remaining lock-up expired in June 2013.

[2] Liquidations are expected over the remaining term.

[3] Of this balance, 5% has a remaining term of less than one year and 95% has a remaining term of 20 years.

[4] Comprised of approximately 33% and 67% of Level 2 and Level 3 assets, respectively, as of June 30, 2013 and 32% and 68% of Level 2 and Level 3 assets, respectively, as of March 31, 2013.