Components Intangible Assets (Details 1) - USD ($) $ in Thousands	Sep. 30, 2015	Mar. 31, 2015
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	$ 3,294,084	$ 3,291,605
U.S. Domestic Mutual Fund Management Contracts
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	2,106,351	2,106,351
Permal/Fauchier Funds-Of-Hedge Fund Management Contracts
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	698,104	698,104
Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	430,176	427,816
Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	59,453	59,334
Asset Management Contracts
Finite-Lived and Indefinite-lived Intangible Assets
Cost	187,230	188,312
Accumulated amortization	(166,573)	(166,583)
Total	20,657	21,729
Consolidated Legg Mason, Inc.
Finite-Lived and Indefinite-lived Intangible Assets
Intangible assets, net	$ 3,314,741	$ 3,313,334

Finite-Lived and Indefinite-Lived Intangible Assets [Line Items]

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274

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