Consolidated Statements of Cash Flows (Consolidated Legg Mason [Domain], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Consolidated Legg Mason [Domain]
Cash Flows from Operating Activities
Net Income (Loss)	$ 68,111	$ 119,081
2.5% Convertible Senior Notes:
Allocation of repurchase payment	(216,038)	0
Loss on extinguishment	68,975	0
Adjustments to reconcile Net Income (Loss) to net cash provided by operations:
Depreciation and amortization	33,480	45,045
Imputed interest for 2.5% Convertible Senior Notes	5,839	19,230
Accretion and amortization of securities discounts and premiums, net	1,790	2,381
Stock-based compensation	27,160	25,948
Net (gains) losses on investments	(23,072)	37,846
Net losses (gains) of consolidated investment vehicles	4,063	2,198
Deferred income taxes	(6,278)	17,701
Other	2,387	901
Decrease (increase) in assets:
Investment advisory and related fees receivable	9,458	40,218
Net (purchases) sales of trading and other current investments	119,265	(44,822)
Other receivables	7,927	(3,605)
Other assets	6,030	14,419
Other assets of consolidated investment vehicles	666	22,479
Increase (decrease) in liabilities:
Accrued compensation	(126,576)	(73,968)
Deferred compensation	(12,583)	(32,134)
Accounts payable and accrued expenses	(2,348)	(18,370)
Other liabilities	(1,469)	9,186
Increase (decrease) in other liabilities of consolidated investment vehicles	(3,666)	(15,565)
Cash Provided by (Used in) Operating Activities	(36,879)	168,169
Cash Flows From Investing Activities
Payments for fixed assets	(18,316)	(14,577)
Change in restricted cash	(757)	7,705
Purchases of investment securities	(4,406)	(3,754)
Proceeds from sales and maturities of investment securities	4,000	3,590
Purchases of investments by consolidated investment vehicles	(74,172)	(113,668)
Proceeds from sales and maturities of investments by consolidated investment vehicles	81,508	123,765
Cash Provided by (Used In) Investing Activities	(12,143)	3,061
Cash Flows From Financing Activities
Repayment of short-term borrowings	(250,000)	0
Repayment of 2.5% Convertible Senior Notes, net of operating allocation	(1,040,212)	0
Repayment of long-term debt	(634)	(391)
Proceeds from issuance of long-term debt	1,143,246	0
Debt issuance cost	(8,642)	0
Issuance of common stock	1,014	1,453
Repurchase of common stock	(252,732)	(400,266)
Dividends paid	(26,251)	(21,029)
Net repayments of consolidated investment vehicles	0	(18,309)
Net (redemptions/distributions paid to)/subscriptions received from noncontrolling interest holders	(2,300)	649
Cash Used In Financing Activities	(436,511)	(437,893)
Effect of Exchange Rate on Cash and Cash Equivalents	1,238	(15,611)
Net Increase (Decrease) in Cash and Cash Equivalents	(484,295)	(282,274)
Cash and Cash Equivalents at Beginning of Period	1,382,263	1,375,918
Cash and Cash Equivalents at End of Period	$ 897,968	$ 1,093,644