| **Non-Insurance Revenues from Contracts with Customers** | 6 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 deferred non-insurance warranty revenue balances of $3.6 billion and $3.4 billion reported in Deferred non-insurance warranty revenue as of June 30, 2019 and December 31, 2018.  For the three and six months ended June 30, 2019, the Company recognized $246 million and $511 million of revenues that were included in the deferred revenue balance as of January 1, 2019.  For the three and six months ended June 30, 2018, the Company recognized $213 million and $435 million of revenues that were included in the deferred revenue balance as of January 1, 2018.  For the three and six months ended June 30, 2019 and 2018, 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 approximately $530 million of the deferred revenue in the remainder of 2019, $927 million in 2020, $746 million in 2021 and $1.4 billion thereafter. |

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| - References
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.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -URI http://asc.fasb.org/topic&trid=49130388
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