| **Financing Arrangement (Carrying Values Of Liability And Equity Components Of Notes) (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2012 | Mar. 31, 2012 |
|--------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Debt Instruments [Abstract]**                                                                                                                  |          |          |  |
| Principal amount of Notes                                                                                                                        | $ 632.5       | $ 632.5       |  |
| Unamortized discount of the liability component                                                                                                  | (79)          | (94)          |  |
| Net carrying amount of Notes                                                                                                                     | 554           | 539           | [1] |
| Equity component, net                                                                                                                            | $ 105         | $ 105         |  |
|                                                                                                                                                  |
| [1]Derived from audited consolidated financial statements.                                                                                       |

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| - Definition
Carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Convertible Notes Payable, excluding current portion. Convertible Notes Payable is a written promise to pay a note which can be exchanged for a specified amount of another, related security, at the option of the issuer and the holder.
+ References
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| - Definition
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 carrying amount of the equity component of convertible debt which may be settled in cash upon conversion.
+ References
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| - Definition
The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.
+ References
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