|
Accumulated Other Comprehensive Income Effects on net income of amounts reclassified from accumulated other comprehensive income (loss) (Details) (USD $)
In Millions, unless otherwise specified
|
12 Months Ended |
|
Mar. 31, 2015
|
Mar. 31, 2014
|
Mar. 31, 2013
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
$ 11 |
$ 9 |
$ (37) |
| Unrealized Gains (Losses) on Available-for-Sale Securities |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
0 |
0 |
(41) |
| Unrealized Gains (Losses) on Available-for-Sale Securities | Investment Income [Member] |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
0 |
0 |
(39) |
| Unrealized Gains (Losses) on Available-for-Sale Securities | Interest Income [Member] |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
0 |
0 |
(2) |
| Unrealized Gains (Losses) on Derivative Instruments |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
11 |
9 |
4 |
| Unrealized Gains (Losses) on Derivative Instruments | Sales Revenue, Net [Member] |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
(2) |
7 |
3 |
| Unrealized Gains (Losses) on Derivative Instruments | Research and Development |
|
|
|
| Accumulated Other Comprehensive Income (Loss) [Line Items] |
|
|
|
| Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax |
$ 13 |
$ 2 |
$ 1 |