Components Intangible Assets (Details 1) - USD ($) $ in Thousands	Sep. 30, 2016		Mar. 31, 2016	Dec. 31, 2015
Finite-Lived and Indefinite-lived Intangible Assets
Cost	$ 430,753		$ 259,513
Accumulated amortization	(183,266)		(171,169)
Total	247,487	[1]	88,344
Indefinite-life intangible assets	3,842,279		3,058,141
U.S. Domestic Mutual Fund Management Contracts
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	2,106,351		2,106,351
Reporting Unit, Percentage of Fair Value in Excess of Carrying Amount				48.00%
Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	547,255		560,499
Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	87,069	[1]	57,187
Permal [Member] | Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	334,104		334,104
EnTrust Capital [Member] | Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	262,300		0
Clarion Partners [Member] | Other Fund Management Contracts [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	505,200		0
Consolidated Legg Mason, Inc.
Finite-Lived and Indefinite-lived Intangible Assets
Intangible assets, net	4,089,766		$ 3,146,485
EnTrust Capital [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Total	62,089
EnTrust Capital [Member] | Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	7,400
Clarion Partners [Member]
Finite-Lived and Indefinite-lived Intangible Assets
Total	98,275
Clarion Partners [Member] | Trade Names
Finite-Lived and Indefinite-lived Intangible Assets
Indefinite-life intangible assets	$ 23,100

[1] As of September 30, 2016, Amortizable intangible asset management contracts, net and Trade names include $98,275 and $23,100, respectively, related to the acquisition of Clarion Partners and $62,089 and $7,400, respectively, related to the acquisition of EnTrust. See Note 3 for additional information.