| **Benefit Plans (Fair Value of Plan Assets Measured on a Recurring Basis) (Details) (USD $)In Millions, unless otherwise specified** | Dec. 31, 2011 | Dec. 31, 2010 |
|--------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| Corporate and other bonds [Member]                                                                                                   |          |          |
| Fair value of plan assets                                                                                                            | $ 387         | $ 315         |
| Corporate and other bonds [Member] | Fair Value, Inputs, Level 1 [Member]                                                            |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Corporate and other bonds [Member] | Fair Value, Inputs, Level 2 [Member]                                                            |          |          |
| Fair value of plan assets                                                                                                            | 377           | 305           |
| Corporate and other bonds [Member] | Fair Value, Inputs, Level 3 [Member]                                                            |          |          |
| Fair value of plan assets                                                                                                            | 10            | 10            |
| States, municipalities and political subdivisions [Member]                                                                           |          |          |
| Fair value of plan assets                                                                                                            | 104           | 92            |
| States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 1 [Member]                                    |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 2 [Member]                                    |          |          |
| Fair value of plan assets                                                                                                            | 104           | 92            |
| States, municipalities and political subdivisions [Member] | Fair Value, Inputs, Level 3 [Member]                                    |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Residential Mortgage Backed Securities [Member]                                                                                      |          |          |
| Fair value of plan assets                                                                                                            | 198           | 179           |
| Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]                                               |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]                                               |          |          |
| Fair value of plan assets                                                                                                            | 198           | 179           |
| Residential Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]                                               |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Commercial Mortgage Backed Securities [Member]                                                                                       |          |          |
| Fair value of plan assets                                                                                                            | 68            | 49            |
| Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 1 [Member]                                                |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 2 [Member]                                                |          |          |
| Fair value of plan assets                                                                                                            | 68            | 40            |
| Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member]                                                |          |          |
| Fair value of plan assets                                                                                                            |     | 9             |
| Other asset-backed [Member]                                                                                                          |          |          |
| Fair value of plan assets                                                                                                            | 10            | 10            |
| Other asset-backed [Member] | Fair Value, Inputs, Level 1 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Other asset-backed [Member] | Fair Value, Inputs, Level 2 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            | 10            | 9             |
| Other asset-backed [Member] | Fair Value, Inputs, Level 3 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            |     | 1             |
| Total asset-backed [Member]                                                                                                          |          |          |
| Fair value of plan assets                                                                                                            | 276           | 238           |
| Total asset-backed [Member] | Fair Value, Inputs, Level 1 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Total asset-backed [Member] | Fair Value, Inputs, Level 2 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            | 276           | 228           |
| Total asset-backed [Member] | Fair Value, Inputs, Level 3 [Member]                                                                   |          |          |
| Fair value of plan assets                                                                                                            |     | 10            |
| Fixed Maturities [Member]                                                                                                            |          |          |
| Fair value of plan assets                                                                                                            | 767           | 645           |
| Fixed Maturities [Member] | Fair Value, Inputs, Level 1 [Member]                                                                     |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Fixed Maturities [Member] | Fair Value, Inputs, Level 2 [Member]                                                                     |          |          |
| Fair value of plan assets                                                                                                            | 757           | 625           |
| Fixed Maturities [Member] | Fair Value, Inputs, Level 3 [Member]                                                                     |          |          |
| Fair value of plan assets                                                                                                            | 10            | 20            |
| Equity securities [Member]                                                                                                           |          |          |
| Fair value of plan assets                                                                                                            | 433           | 504           |
| Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]                                                                    |          |          |
| Fair value of plan assets                                                                                                            | 353           | 421           |
| Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]                                                                    |          |          |
| Fair value of plan assets                                                                                                            | 75            | 77            |
| Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]                                                                    |          |          |
| Fair value of plan assets                                                                                                            | 5             | 6             |
| Short-term Investments [Member]                                                                                                      |          |          |
| Fair value of plan assets                                                                                                            | 98            | 113           |
| Short-term Investments [Member] | Fair Value, Inputs, Level 1 [Member]                                                               |          |          |
| Fair value of plan assets                                                                                                            | 63            | 106           |
| Short-term Investments [Member] | Fair Value, Inputs, Level 2 [Member]                                                               |          |          |
| Fair value of plan assets                                                                                                            | 35            | 7             |
| Short-term Investments [Member] | Fair Value, Inputs, Level 3 [Member]                                                               |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Hedge Funds [Member]                                                                                                                 |          |          |
| Fair value of plan assets                                                                                                            | 818           | 912           |
| Hedge Funds [Member] | Fair Value, Inputs, Level 1 [Member]                                                                          |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Hedge Funds [Member] | Fair Value, Inputs, Level 2 [Member]                                                                          |          |          |
| Fair value of plan assets                                                                                                            | 488           | 518           |
| Hedge Funds [Member] | Fair Value, Inputs, Level 3 [Member]                                                                          |          |          |
| Fair value of plan assets                                                                                                            | 330           | 394           |
| Private Equity Funds [Member]                                                                                                        |          |          |
| Fair value of plan assets                                                                                                            | 65            | 59            |
| Private Equity Funds [Member] | Fair Value, Inputs, Level 1 [Member]                                                                 |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Private Equity Funds [Member] | Fair Value, Inputs, Level 2 [Member]                                                                 |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Private Equity Funds [Member] | Fair Value, Inputs, Level 3 [Member]                                                                 |          |          |
| Fair value of plan assets                                                                                                            | 65            | 59            |
| Total limited partnerships [Member]                                                                                                  |          |          |
| Fair value of plan assets                                                                                                            | 883           | 971           |
| Total limited partnerships [Member] | Fair Value, Inputs, Level 1 [Member]                                                           |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Total limited partnerships [Member] | Fair Value, Inputs, Level 2 [Member]                                                           |          |          |
| Fair value of plan assets                                                                                                            | 488           | 518           |
| Total limited partnerships [Member] | Fair Value, Inputs, Level 3 [Member]                                                           |          |          |
| Fair value of plan assets                                                                                                            | 395           | 453           |
| Derivative [Member]                                                                                                                  |          |          |
| Fair value of plan assets                                                                                                            |          | 1             |
| Derivative [Member] | Fair Value, Inputs, Level 1 [Member]                                                                           |          |          |
| Fair value of plan assets                                                                                                            |          | 1             |
| Derivative [Member] | Fair Value, Inputs, Level 2 [Member]                                                                           |          |          |
| Fair value of plan assets                                                                                                            |          |     |
| Derivative [Member] | Fair Value, Inputs, Level 3 [Member]                                                                           |          |          |
| Fair value of plan assets                                                                                                            |          |     |
| Other Assets [Member]                                                                                                                |          |          |
| Fair value of plan assets                                                                                                            | 21            | 15            |
| Other Assets [Member] | Fair Value, Inputs, Level 1 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Other Assets [Member] | Fair Value, Inputs, Level 2 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            | 21            | 15            |
| Other Assets [Member] | Fair Value, Inputs, Level 3 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Investment Contracts with Insurance Company [Member]                                                                                 |          |          |
| Fair value of plan assets                                                                                                            | 10            | 9             |
| Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 1 [Member]                                          |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 2 [Member]                                          |          |          |
| Fair value of plan assets                                                                                                            |     |     |
| Investment Contracts with Insurance Company [Member] | Fair Value, Inputs, Level 3 [Member]                                          |          |          |
| Fair value of plan assets                                                                                                            | 10            | 9             |
| Total assets [Member]                                                                                                                |          |          |
| Fair value of plan assets                                                                                                            | 2,212         | 2,258         |
| Total assets [Member] | Fair Value, Inputs, Level 1 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            | 416           | 528           |
| Total assets [Member] | Fair Value, Inputs, Level 2 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            | 1,376         | 1,242         |
| Total assets [Member] | Fair Value, Inputs, Level 3 [Member]                                                                         |          |          |
| Fair value of plan assets                                                                                                            | $ 420         | $ 488         |

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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
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=6867990&loc=d3e12355-114930Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 49 -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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920
+ Details**Name:**us-gaap_DefinedBenefitPlanFairValueOfPlanAssets**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |