| **Benefit Plans (Tables)**                            | 3 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                     |
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| **Compensation and Retirement Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                               |
| Components of net periodic cost (benefit)             | The components of net periodic cost (benefit) are presented in the following table.Three months ended March 31   (In millions)2016 2015Pension cost (benefit)   Service cost$— $2Interest cost on projected benefit obligation28 28Expected return on plan assets(40) (43)Amortization of net actuarial loss9 9Net periodic pension cost (benefit)$(3) $(4) |

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| - References
No definition available.
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| - Definition
Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920
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