| **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] |  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, 2011$125 $(2) $96 $219Other comprehensive loss before reclassifications(40) (4) (4) (48)Amounts reclassified from accumulated other comprehensive income(2) 4 — 2Net current-period other comprehensive income (loss)(42) — (4) (46)Balances as of March 31, 2012$83 $(2) $92 $173Other comprehensive loss before reclassifications$(46) $(2) $(19) $(67)Amounts reclassified from accumulated other comprehensive income(41) 4 — (37)Net current-period other comprehensive income (loss)(87) 2 (19) (104)Balances as of March 31, 2013(4) — 73 69Other comprehensive loss before reclassifications$— $(19) $(22) $(41)Amounts reclassified from accumulated other comprehensive income— 9 — 9Net current-period other comprehensive income (loss)— (10) (22) (32)Balances as of March 31, 2014(4) (10) 51 37The effects on net loss of amounts reclassified from accumulated other comprehensive income (loss) for the fiscal years ended March 31, 2014, 2013 and 2012 were as follows (in millions):  Amount Reclassified From Accumulated Other Comprehensive Income (loss)  Details about Accumulated Other Comprehensive Income (Loss) Components Year Ended March 31, 2014 Year Ended March 31, 2013 Year Ended March 31, 2012 Statement of Operations ClassificationReclassification adjustment for realized gains on available-for-sale securities          $— $(39) $— Gains on strategic investments  — (2) (2) Interest and other income (expense)  — (41) (2) Net of tax         Reclassification adjustment for net realized losses on derivative instruments          7 3 3 Net revenue  2 1 1 Research and development  9 4 4 Net of tax         Total amount reclassified, net of tax $9 $(37) $2   |

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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=28358780&loc=SL7669686-108580
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