| **Non-Insurance Revenues from Contracts with Customers** | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
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| **Revenue from Contract with Customer [Abstract]**       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Non-Insurance Revenues from Contracts with Customers     | Non-Insurance Revenues from Contracts with CustomersThe Company had balances of $4.7 billion reported in Deferred non-insurance warranty revenue as of September 30, 2023 and December 31, 2022.  For the three and nine months ended September 30, 2023, the Company recognized $0.2 billion and $0.9 billion of revenues that were included in the deferred revenue balance as of January 1, 2023.  For the three and nine months ended September 30, 2022, the Company recognized $0.3 billion and $1.0 billion of revenues that were included in the deferred revenue balance as of January 1, 2022.  For the three and nine months ended September 30, 2023, non-insurance warranty revenue recognized from performance obligations related to prior periods due to a change in estimate was not material.  The Company expects to recognize $0.4 billion of the deferred revenue in the remainder of 2023, $1.3 billion in 2024, $1.0 billion in 2025 and $2.0 billion thereafter. |

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No definition available.
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| - Definition
The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.
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