| **Benefit Plans (Estimated Future Minimum Benefit Payments to Participants) (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2012 |
|----------------------------------------------------------------------------------------------------------------------------------------|---------------|
| Pension Plans, Defined Benefit [Member]                                                                                                |          |
| Defined Benefit Plan, Expected Future Benefit Payments in Year One                                                                     | $ 186         |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Two                                                                     | 187           |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Three                                                                   | 193           |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Four                                                                    | 194           |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Five                                                                    | 200           |
| Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter                                                 | 1,024         |
| Other Postretirement Benefit Plans, Defined Benefit [Member]                                                                           |          |
| Defined Benefit Plan, Expected Future Benefit Payments in Year One                                                                     | 6             |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Two                                                                     | 5             |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Three                                                                   | 5             |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Four                                                                    | 5             |
| Defined Benefit Plan, Expected Future Benefit Payments in Year Five                                                                    | 5             |
| Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter                                                 | $ 16          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid  in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.
+ 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 (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920
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