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Summary of Contractual Maturities of Cash Equivalent and Marketable Fixed Income Securities (Detail) (USD $)
In Millions, unless otherwise specified |
Mar. 31, 2013
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|---|---|
| Investments Classified by Contractual Maturity Date [Line Items] | |
| Amortized Cost | $ 5,828 |
| Estimated Fair Value | 5,840 |
|
Due within one year
|
|
| Investments Classified by Contractual Maturity Date [Line Items] | |
| Amortized Cost | 3,565 |
| Estimated Fair Value | 3,568 |
|
Due after one year through five years
|
|
| Investments Classified by Contractual Maturity Date [Line Items] | |
| Amortized Cost | 1,986 |
| Estimated Fair Value | 1,994 |
|
Due After Five Years
|
|
| Investments Classified by Contractual Maturity Date [Line Items] | |
| Amortized Cost | 277 |
| Estimated Fair Value | $ 278 |