Fair Values of Assets and Liabilities (Details 1) (Legg Mason Group, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Quoted prices in active markets (Level 1)
Cash equivalents:
Money market funds	$ 485,776		$ 893,738
Time deposits and other	0		0
Total cash equivalents	485,776		893,738
Current investments:
Trading investments relating to long-term incentive compensation plans	86,583		111,257
Trading proprietary fund products and other investments	158,846		143,002
Equity method investments relating to long-term incentive compensation plans, proprietary fund products and other investments	12,600		11,565
Total current investments	258,029		265,824
Available-for-sale investment securities	2,034		2,091
Investments in partnerships, LLCs and other	761		851
Equity method investments in partnerships and LLCs	1,518		1,415
Derivative Assets:
Currency and market hedges	1,939		84
Other investments	0		0
Financial assets measured at fair value	750,057		1,164,003
Derivative liabilities:
Currency and market hedges	(781)		(886)
Significant other observable inputs (Level 2)
Cash equivalents:
Money market funds	0		0
Time deposits and other	177,471		88,289
Total cash equivalents	177,471		88,289
Current investments:
Trading investments relating to long-term incentive compensation plans	0		0
Trading proprietary fund products and other investments	69,064		79,583
Equity method investments relating to long-term incentive compensation plans, proprietary fund products and other investments	43,741		54,934
Total current investments	112,805		134,517
Available-for-sale investment securities	10,354		9,810
Investments in partnerships, LLCs and other	2,620		5,351
Equity method investments in partnerships and LLCs	924		1,348
Derivative Assets:
Currency and market hedges	0		0
Other investments	0		0
Financial assets measured at fair value	304,174		239,315
Derivative liabilities:
Currency and market hedges	0		0
Significant unobservable inputs (Level 3)
Cash equivalents:
Money market funds	0		0
Time deposits and other	0		0
Total cash equivalents	0		0
Current investments:
Trading investments relating to long-term incentive compensation plans	0		0
Trading proprietary fund products and other investments	246		0
Equity method investments relating to long-term incentive compensation plans, proprietary fund products and other investments	0		11,778
Total current investments	246		11,778
Available-for-sale investment securities	12		12
Investments in partnerships, LLCs and other	27,762		28,763
Equity method investments in partnerships and LLCs	66,338		166,438
Derivative Assets:
Currency and market hedges	0		0
Other investments	99		112
Financial assets measured at fair value	94,457		207,103
Derivative liabilities:
Currency and market hedges	0		0
Total
Cash equivalents:
Money market funds	485,776	[1]	893,738	[1]
Time deposits and other	177,471	[1]	88,289	[1]
Total cash equivalents	663,247	[1]	982,027	[1]
Current investments:
Trading investments relating to long-term incentive compensation plans	86,583	[2]	111,257	[2]
Trading proprietary fund products and other investments	228,156	[3]	222,585	[3]
Equity method investments relating to long-term incentive compensation plans, proprietary fund products and other investments	56,341	[4],[5]	78,277	[4],[5]
Total current investments			412,119
Available-for-sale investment securities	12,400	[6]	11,913	[6]
Investments in partnerships, LLCs and other	31,143	[6]	34,965	[6]
Equity method investments in partnerships and LLCs	68,780	[4],[6]	169,201	[4],[6]
Derivative Assets:
Currency and market hedges	1,939		84
Other investments	99	[6]	112	[6]
Financial assets measured at fair value	1,148,688		1,610,421
Derivative liabilities:
Currency and market hedges	(781)		(886)
Cash and Cash Equivalents, Maturity Period	90
Proprietary fund products disclosures
Proprietary fund products and other investments, equity securities percentage (as a percent)	49.00%		52.00%
Proprietary fund products and other investments, debt securities percentage (as a percent)	51.00%		48.00%
Equity method investments relating to long-term incentive compensation plans	43,741		54,934
Equity method investments relating to proprietary fund products and other investments	$ 12,600		$ 23,343

[1] Cash equivalents include highly liquid investments with original maturities of 90 days or less. Cash investments in actively traded money market funds are measured at NAV and are classified as Level 1. Cash investments in time deposits and other are measured at amortized cost, which approximates fair value because of the short time between the purchase of the instrument and its expected realization, and are classified as Level 2.

[2] Primarily mutual funds where there is minimal market risk to the Company as any change in value is primarily offset by an adjustment to compensation expense and related deferred compensation liability.

[3] Trading proprietary fund products and other investments primarily represent mutual funds that are invested approximately 49% and 51% in equity and debt securities, respectively, as of March 31, 2013, and were invested approximately 52% and 48% in equity and debt securities, respectively, as of March 31, 2012.

[4] Substantially all of Legg Mason's equity method investments are investment companies which record their underlying investments at fair value. Fair value is measured using Legg Mason's share of the investee's underlying net income or loss, which is predominately representative of fair value adjustments in the investments held by the equity method investee.

[5] Includes investments under the equity method (which approximates fair value) relating to long-term incentive compensation plans of $43,741 and $54,934 as of March 31, 2013 and March 31, 2012, respectively, and proprietary fund products and other investments of $12,600 and $23,343 as of March 31, 2013 and March 31, 2012, respectively, which are classified as Investment securities on the Consolidated Balance Sheets.

[6] Amounts are included in Other non-current assets on the Consolidated Balance Sheets for each of the periods presented.