| **Net Income Per Common Share (Tables)**              | 12 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) Years ended December 31, 2014 2013 2012Numerator:      Net income—basic and diluted $525 $517 $421Denominator:      Basic weighted-average common shares outstanding 163.5 163.5 162.5Effect of stock-based awards:      Stock options 1.0 1.2 0.5Nonvested shares 0.6 0.7 0.7Diluted weighted-average shares 165.1 165.4 163.7Earnings per share:      Basic $3.21 $3.16 $2.59Diluted 3.18 3.12 2.57Number of anti-dilutive stock-based awards 0.7 0.4 5.9        |

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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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