| **Benefit Plans (Reconciliation of Level 3 Plan Assets) (Details) (USD $)In Millions, unless otherwise specified** | 12 Months Ended |              |
|--------------------------------------------------------------------------------------------------------------------|-----------------|--------------|
||
| Corporate and other bonds [Member]                                                                                 |            |         |   |
| Fair value of plan assets                                                                                          | $ 447           | $ 387        |   |
| Commercial Mortgage Backed Securities [Member]                                                                     |            |         |   |
| Fair value of plan assets                                                                                          | 105             | 68           |   |
| Other asset-backed [Member]                                                                                        |            |         |   |
| Fair value of plan assets                                                                                          |            | 10           |   |
| Total asset-backed [Member]                                                                                        |            |         |   |
| Fair value of plan assets                                                                                          | 266             | 276          |   |
| Fixed Maturities [Member]                                                                                          |            |         |   |
| Fair value of plan assets                                                                                          | 804             | 767          |   |
| Equity securities [Member]                                                                                         |            |         |   |
| Fair value of plan assets                                                                                          | 493             | 433          |   |
| Hedge Funds [Member]                                                                                               |            |         |   |
| Fair value of plan assets                                                                                          | 896             | 818          |   |
| Private Equity Funds [Member]                                                                                      |            |         |   |
| Fair value of plan assets                                                                                          | 62              | 65           |   |
| Total limited partnerships [Member]                                                                                |            |         |   |
| Fair value of plan assets                                                                                          | 958             | 883          |   |
| Investment Contracts with Insurance Company [Member]                                                               |            |         |   |
| Fair value of plan assets                                                                                          | 10              | 10           |   |
| Total assets [Member]                                                                                              |            |         |   |
| Fair value of plan assets                                                                                          | 2,425           | 2,212        |   |
| Fair Value, Inputs, Level 3 [Member] | Corporate and other bonds [Member]                                          |            |         |   |
| Fair value of plan assets                                                                                          | 11              | 10           | 10 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 1               |    |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |       |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |       |    |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Commercial Mortgage Backed Securities [Member]                              |            |         |   |
| Fair value of plan assets                                                                                          |       |    | 9 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      |            |    |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |            |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |            | (9)          |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |            |    |   |
| Fair Value, Inputs, Level 3 [Member] | Other asset-backed [Member]                                                 |            |         |   |
| Fair value of plan assets                                                                                          |            |    | 1 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      |            |    |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |            |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |            | (1)          |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |            |    |   |
| Fair Value, Inputs, Level 3 [Member] | Total asset-backed [Member]                                                 |            |         |   |
| Fair value of plan assets                                                                                          |       |    | 10 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      |            |    |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |            |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |            | (10)         |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |            |    |   |
| Fair Value, Inputs, Level 3 [Member] | Fixed Maturities [Member]                                                   |            |         |   |
| Fair value of plan assets                                                                                          | 11              | 10           | 20 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 1               |    |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |       |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |       | (10)         |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Equity securities [Member]                                                  |            |         |   |
| Fair value of plan assets                                                                                          | 5               | 5            | 6 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      |       | (1)          |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |       |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |       |    |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Hedge Funds [Member]                                                        |            |         |   |
| Fair value of plan assets                                                                                          | 359             | 330          | 394 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 41              | 5            |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              | 3               | 5            |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            | (15)            | (74)         |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Private Equity Funds [Member]                                               |            |         |   |
| Fair value of plan assets                                                                                          | 62              | 65           | 59 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 8               | 9            |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |       |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            | (11)            | (3)          |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Total limited partnerships [Member]                                         |            |         |   |
| Fair value of plan assets                                                                                          | 421             | 395          | 453 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 49              | 14           |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              | 3               | 5            |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            | (26)            | (77)         |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Investment Contracts with Insurance Company [Member]                        |            |         |   |
| Fair value of plan assets                                                                                          | 10              | 10           | 9 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      |       | 1            |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              |       |    |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            |       |    |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |
| Fair Value, Inputs, Level 3 [Member] | Total assets [Member]                                                       |            |         |   |
| Fair value of plan assets                                                                                          | 447             | 420          | 488 |
| Defined Benefit Plan, Actual Return on Plan Assets Still Held                                                      | 50              | 14           |   |
| Defined Benefit Plan, Actual Return on Plan Assets Sold During Period                                              | 3               | 5            |   |
| Defined Benefit Plan, Purchases, Sales, and Settlements                                                            | (26)            | (87)         |   |
| Defined Benefit Plan, Net transfers into (out of) Level 3                                                          |       |    |   |

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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Actual return on plan assets, separately identifying the amount related to assets sold during the period.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph d(iv)(b)(i) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c)(iv)(02)(A) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e2446-114920
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Actual return on plan assets, separately identifying the amount related to assets still held at the reporting date.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Purchases, sales, and settlements of plan assets that occurred during the period.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Transfers in and out of Level 3. For example, transfers due to changes in the observability of significant inputs.
+ References
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