| **Earnings (Loss) Per Share (Tables)**                                     | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
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| **Earnings Per Share Reconciliation [Abstract]**                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Computation Of Basic Earnings (Loss) And Diluted Earnings (Loss) Per Share | The following table summarizes the computations of basic earnings per share (“Basic EPS”) and diluted earnings per share (“Diluted EPS”). Basic EPS is computed as net income divided by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur from common shares issuable through stock-based compensation plans including stock options, restricted stock, restricted stock units, common stock through our ESPP, warrants, and other convertible securities using the treasury stock method. Three Months Ended December 31,  Nine Months Ended December 31,(In millions, except per share amounts)2015 2014 2015 2014Net income (loss)$(45) $142 $257 $480Shares used to compute earnings (loss) per share:       Weighted-average common stock outstanding — basic311 311 311 312Dilutive potential common shares related to stock award plans and from assumed exercise of stock options— 8 7 8Dilutive potential common shares related to the Notes— 4 8 2Dilutive potential common shares related to the Warrants— — 7 —Weighted-average common stock outstanding — diluted311 323 333 322Earnings (loss) per share:       Basic$(0.14) $0.46 $0.83 $1.54Diluted$(0.14) $0.44 $0.77 $1.49 |

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| - References
No definition available.
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| - Definition
Tabular disclosure of an entity's basic and diluted earnings per share calculations, including a reconciliation of numerators and denominators of the basic and diluted per-share computations for income from continuing operations.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257
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