| **Net Income Per Common Share (Tables)**              | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
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| **Earnings Per Share [Abstract]**                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
| Calculations For Basic And Diluted Earnings Per Share | The table shows calculations for basic and diluted earnings per share:(In millions except per share data)Three months ended March 31,2016 2015Numerator:   Net income—basic and diluted$188 $128Denominator:   Basic weighted-average common shares outstanding164.2 164.0Effect of share-based awards:   Stock options1.0 1.0Nonvested shares0.8 0.6Diluted weighted-average shares 166.0 165.6Earnings per share:   Basic$1.14 $0.78Diluted1.13 0.77Number of anti-dilutive share-based awards:0.4 0.7     |

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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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