| **Benefit Plans (Schedule of Non-Service Cost (Benefit) Presented in the Consolidated Statement of Operations) (Details) - Pension Benefits - USD ($) $ in Millions** | 12 Months Ended |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
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| **Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]**                                                                        |            |   |   |
| Net periodic defined benefits expense (reversal of expense), excluding service cost component                                                                         | $ (55)          | $ (45) | $ (27) |
| Insurance claims and policyholder's benefits                                                                                                                          |            |   |   |
| **Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]**                                                                        |            |   |   |
| Net periodic defined benefits expense (reversal of expense), excluding service cost component                                                                         | (15)            | (13) | (8) |
| Other operating expenses                                                                                                                                              |            |   |   |
| **Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]**                                                                        |            |   |   |
| Net periodic defined benefits expense (reversal of expense), excluding service cost component                                                                         | $ (40)          | $ (32) | $ (19) |

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| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
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| - Definition
Amount of expense (reversal of expense) for net periodic benefit cost components, excluding service cost component, of defined benefit plan. Amount includes, but is not limited to, interest cost, expected (return) loss on plan asset, amortization of prior service cost (credit), amortization of (gain) loss, amortization of transition (asset) obligation, settlement (gain) loss, curtailment (gain) loss and certain termination benefits.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 45 -Paragraph 3A -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123453770&loc=SL108413299-114919
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| X                                                                                                                                                               |
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| X                                                                                                                                                                                                            |
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| X                                                                                                                                                                     |
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