| **General (Narrative) (Details) - USD ($) $ in Millions**                                                     | 9 Months Ended                               |         |
|---------------------------------------------------------------------------------------------------------------|----------------------------------------------|---------|
||
| **New Accounting Pronouncements or Change in Accounting Principle [Line Items]**                              |                                         |    |
| Accounting Standards Update [Extensible Enumeration]                                                          | Accounting Standards Update 2018-12 [Member] |    |
| Pro Forma | Accumulated Other Comprehensive (Loss) Income | Cumulative Effect, Period of Adoption, Adjustment |                                         |    |
| **New Accounting Pronouncements or Change in Accounting Principle [Line Items]**                              |                                         |    |
| Decrease in accumulated other comprehensive income                                                            |                                         | $ 2,300 |
| Loews | CNAF Consolidated                                                                                     |                                         |    |
| **New Accounting Pronouncements or Change in Accounting Principle [Line Items]**                              |                                         |    |
| Noncontrolling interest, ownership percentage by parent (as a percent)                                        | 90.00%                                       |    |

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| - Definition
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The parent entity's interest in net assets of the subsidiary, expressed as a percentage.
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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.
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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.
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