| **Benefit Plans (Tables)**                                                                       | 6 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 June 30Three Months Six Months(In millions)2012 2011 2012 2011Pension cost (benefit)       Service cost$3 $3 $6 $7Interest cost on projected benefit obligation33 36 67 73Expected return on plan assets(42) (43) (85) (86)Amortization of net actuarial (gain) loss9 6 19 12Net periodic pension cost (benefit)$3 $2 $7 $6        Postretirement cost (benefit)       Interest cost on projected benefit obligation$1 $1 $1 $2Amortization of prior service credit(5) (4) (9) (9)Amortization of net actuarial (gain) loss— (1) — —Net periodic postretirement cost (benefit)$(4) $(4) $(8) $(7) |

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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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