Consolidated Balance Sheets (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Common Stock, Par or Stated Value Per Share	$ 0.10	$ 0.10
Current Assets
Cash and cash equivalents	$ 400,000
Receivables:
Fixed assets, net	179,606us-gaap_PropertyPlantAndEquipmentNet	189,241us-gaap_PropertyPlantAndEquipmentNet
STOCKHOLDERS' EQUITY
Accumulated other comprehensive income, net	(60,742)	37,949
Common Stock, Shares Authorized	500,000,000us-gaap_CommonStockSharesAuthorized	500,000,000us-gaap_CommonStockSharesAuthorized
Common Stock, Shares, Issued	111,469,142us-gaap_CommonStockSharesIssued	117,173,639us-gaap_CommonStockSharesIssued
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Current Assets
Cash and cash equivalents	669,552	858,022
Receivables:
Investment securities	454,735	467,726
Other current assets	51,750	47,677
Other non-current assets	157,514	183,706
Current Liabilities
Current portion of long-term debt	0	438
Business Combination, Contingent Consideration, Liability, Current	22,276	0
Other current liabilities	177,879	91,586
Business Combination, Contingent Consideration, Liability, Noncurrent	88,508	29,553
Other non-current liabilities	167,998	136,656
Long-term Debt	1,058,089	1,038,826
Consolidated Investment Vehicles [Member]
Current Assets
Cash and cash equivalents	2,808	56,372
Receivables:
Investment securities	48,000	50,463
Other current assets	6,121	31,910
Investments of consolidated investment vehicles	0	31,810
Current Liabilities
Other current liabilities	6,436	88,936
REDEEMABLE NONCONTROLLING INTERESTS	38,498	43,328
Consolidated Legg Mason, Inc.
Current Assets
Restricted cash	32,114	13,455
Receivables:
Investment advisory and related fees	368,399	348,633
Other receivables	118,850	68,186
Deferred income taxes	169,706	186,147
Total Current Assets	1,922,035	2,128,591
Fixed assets, net	179,606	189,241
Intangible assets, net	3,313,334	3,171,773
Goodwill	1,339,510	1,240,523
Deferred income taxes	161,978	165,705
TOTAL ASSETS	7,073,977	7,111,349
Current Liabilities
Accrued compensation	400,245	425,466
Accounts Payable and Accrued Liabilities, Current	208,210	214,819
Total Current Liabilities	815,046	821,245
Deferred compensation	51,706	49,618
Deferred income taxes	362,209	265,583
TOTAL LIABILITIES	2,543,556	2,341,481
REDEEMABLE NONCONTROLLING INTERESTS	45,520	45,144
STOCKHOLDERS' EQUITY
Common stock, par value $.10; authorized 500,000,000 shares; issued 111,469,142 shares in March 2015 and 117,173,639 shares in March 2014	11,147	11,717
Additional paid-in capital	2,844,441	3,148,396
Employee stock trust	(29,570)	(29,922)
Deferred compensation employee stock trust	29,570	29,922
Retained earnings	1,690,055	1,526,662
Accumulated other comprehensive income, net	(60,742)	37,949
TOTAL STOCKHOLDERS' EQUITY	4,484,901	4,724,724
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	7,073,977	7,111,349
Management Equity Plan [Member] \| Consolidated Legg Mason, Inc.
Current Liabilities
REDEEMABLE NONCONTROLLING INTERESTS	$ 7,022	$ 1,816

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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Aggregate carrying amount, as of the balance sheet date, of noncurrent obligations not separately disclosed in the balance sheet. Noncurrent liabilities are expected to be paid after one year (or the normal operating cycle, if longer).

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The carrying amount of other receivables, net, due within one year of the balance sheet date (or one operating cycle, if longer) from third parties or arising from transactions not separately disclosed.

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No definition available.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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As of the reporting date, the aggregate carrying amount of all noncontrolling interests which are redeemable by the (parent) entity (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the (parent) entity. This item includes noncontrolling interest holder's ownership (or holders' ownership) regardless of the type of equity interest (common, preferred, other) including all potential organizational (legal) forms of the investee entity.

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The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

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A segregation of retained earnings which is available for dividend distribution. Earnings not paid out as dividends but instead reinvested in the core business or used to pay off debt. Unappropriated profit is part of shareholder equity. Also called cumulative distributions or earned surplus or accumulated earnings or unappropriated profit.

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Investments which are intended to be sold in the short term (usually less than one year or the normal operating cycle, whichever is longer) including trading securities, available-for-sale securities, held-to-maturity securities, and other short-term investments not otherwise listed in the existing taxonomy.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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