Commitments and Contingencies Information Regarding Other Commitments (Details 4) - USD ($) $ in Thousands		Sep. 30, 2015	Mar. 31, 2015
Other Noncurrent Liabilities [Member]
Other Commitments [Line Items]
Business Combination, Contingent Consideration, Liability	[1]	$ 90,219
Investment In Limited Partnerships [Member]
Other Commitments [Line Items]
Other Commitment		29,484
Consolidated Legg Mason, Inc.
Other Commitments [Line Items]
Business Combination, Contingent Consideration, Liability, Current		$ 13,332	$ 22,276

[1] See Note 3.