Schedule of Fixed Assets (Details) (Legg Mason, Inc, USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Fixed assets:
Total cost	$ 606,778	$ 602,064
Less: accumulated depreciation and amortization	(417,537)	(400,245)
Fixed assets, net	189,241	201,819
Equipment
Fixed assets:
Total cost	147,663	152,065
Software and Software Development Costs
Fixed assets:
Total cost	249,368	227,739
Leasehold improvements
Fixed assets:
Total cost	$ 209,747	$ 222,260