| **Benefit Plans (Tables)**                                                                       | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
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| **Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Components of net periodic cost (benefit)                                                        | Net Periodic Cost (Benefit)Periods ended September 30Three Months Nine Months(In millions)2012 2011 2012 2011Pension cost (benefit)       Service cost$3 $3 $9 $10Interest cost on projected benefit obligation34 37 101 110Expected return on plan assets(43) (44) (128) (130)Amortization of net actuarial (gain) loss10 7 29 19Net periodic pension cost (benefit)$4 $3 $11 $9        Postretirement cost (benefit)       Interest cost on projected benefit obligation$1 $1 $2 $3Amortization of prior service credit(4) (5) (13) (14)Net periodic postretirement cost (benefit)$(3) $(4) $(11) $(11) |

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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 -Topic 715 -SubTopic 20 -Publisher FASB -Number  -Article  -Subparagraph (h) -Name Accounting Standards Codification -Paragraph 1 -Section 50 -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920
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