|
(Fair Value Of Short-Term Investments By Stated Maturity Date Schedule) (Details) (USD $)
In Millions, unless otherwise specified
|
Mar. 31, 2015
|
Mar. 31, 2014
|
| Financial Instruments [Line Items] |
|
|
| Short-term investments, Fair Value |
$ 953 |
$ 583 |
| Short-Term Investments [Member] |
|
|
| Financial Instruments [Line Items] |
|
|
| Short-term investments, Amortized Cost |
952 |
583 |
| Short-term investments, Fair Value |
953 |
583 |
| Due in 1 year or less [Member] | Short-Term Investments [Member] |
|
|
| Financial Instruments [Line Items] |
|
|
| Due in 1 year or less, Amortized Cost |
417 |
318 |
| Due in 1 year or less, Fair Value |
417 |
318 |
| Due in 1-2 years [Member] |
|
|
| Financial Instruments [Line Items] |
|
|
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis |
281 |
156 |
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value |
281 |
156 |
| Due in 2-3 years [Member] | Short-Term Investments [Member] |
|
|
| Financial Instruments [Line Items] |
|
|
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis |
244 |
104 |
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value |
245 |
104 |
| Due in 3-4 years [Member] | Short-Term Investments [Member] |
|
|
| Financial Instruments [Line Items] |
|
|
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis |
10 |
5 |
| Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value |
$ 10 |
$ 5 |