| **Accumulated other Comprehensive Income (Tables)**                               | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
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| **Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]**          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| Components of Accumulated Other Comprehensive Income (Loss) [Table Text Block]    | fiscal years ended March 31, 2016, 2015 and 2014 are as follows (in millions): Unrealized Net Gains (Losses) on Available-for-Sale Securities Unrealized Net Gains (Losses) on Derivative Instruments Foreign Currency Translation Adjustments TotalBalances as of March 31, 2013$(4) $— $73 $69Other comprehensive income (loss) before reclassifications— (19) (22) (41)Amounts reclassified from accumulated other comprehensive income (loss)— 9 — 9Net current-period other comprehensive income (loss)— (10) (22) (32)Balances as of March 31, 2014$(4) $(10) $51 $37Other comprehensive income (loss) before reclassifications$1 $20 $(67) $(46)Amounts reclassified from accumulated other comprehensive income— 11 — 11Net current-period other comprehensive income (loss)1 31 (67) (35)Balances as of March 31, 2015(3) 21 (16) 2Other comprehensive income (loss) before reclassifications$4 $5 $(15) $(6)Amounts reclassified from accumulated other comprehensive income— (12) — (12)Net current-period other comprehensive income (loss)4 (7) (15) (18)Balances as of March 31, 20161 14 (31) (16) |
| Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] | The effects on net income of amounts reclassified from accumulated other comprehensive income (loss) for the fiscal years ended March 31, 2016, 2015 and 2014 were as follows (in millions): Statement of Operations Classification Amount Reclassified From Accumulated Other Comprehensive Income (Loss)Year Ended March 31,2016 2015 2014(Gains) losses on cash flow hedges from forward contracts      Net revenue (23) (2) 7Research and development 11 13 2Total amount reclassified, net of tax $(12) $11 $9                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |

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| - References
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| - Definition
Tabular disclosure of information about items reclassified out of accumulated other comprehensive income (loss).
+ References
No definition available.
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| - Definition
Tabular disclosure of the components of accumulated other comprehensive income (loss).
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=36458714&loc=SL7669686-108580
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