Long-Term Debt and Equity Units (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Mar. 31, 2011
Debt Instrument [Line Items]
Unamortized Discount	$ 133,045
Legg Mason, Inc.
Debt Instrument [Line Items]
Accreted Value of Long-term debt	1,127,041	1,201,868
Less: current portion	1,266	792
Total	1,125,775	1,201,076
Unamortized Discount	133,045
Maturity Amount	1,260,086
Debt Instrument Maturity Amount, Current	1,266
Total Maturity Amount, noncurrent	1,258,820
Legg Mason, Inc. \| 2.5% convertible senior notes
Debt Instrument [Line Items]
Accreted Value of Long-term debt	1,116,955	1,087,932
Unamortized Discount	133,045
Maturity Amount	1,250,000
Legg Mason, Inc. \| 5.6% senior notes from Equity Units
Debt Instrument [Line Items]
Accreted Value of Long-term debt	0	103,039
Unamortized Discount	0
Maturity Amount	0
Legg Mason, Inc. \| Other term loans [Member]
Debt Instrument [Line Items]
Accreted Value of Long-term debt	10,086	10,897
Unamortized Discount	0
Maturity Amount	$ 10,086

The current portion of the amount due to satisfy the obligation at the maturity date.

No definition available.

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- Definition

The noncurrent portion of the aggregate carrying amount of all long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any), which is debt initially having maturities due after one year from the balance sheet date.

+ References

No definition available.

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Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

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- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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Total of the portions of the carrying amounts as of the balance sheet date of long-term debt, which may include notes payable, bonds payable, debentures, mortgage loans, and commercial paper, which are scheduled to be repaid within one year or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year (current maturities) or the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

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