| **Non-Insurance Revenues from Contracts with Customers (Details) - USD ($) $ in Millions**       | 3 Months Ended | 9 Months Ended |         |
|--------------------------------------------------------------------------------------------------|----------------|----------------|---------|
||
| **Disaggregation of Revenue [Line Items]**                                                       |           |           |    |
| Unearned revenue associated with outstanding non-insurance warrany product and service contracts | $ 3,300        | $ 3,300        | $ 2,900 |
| Contract with customer, liability, revenue recognized                                            | 200            | 635            |    |
| Amortization of deferred sales commissions                                                       | 173            | $ 494          |    |
| Minimum                                                                                          |           |           |    |
| **Disaggregation of Revenue [Line Items]**                                                       |           |           |    |
| Warranty contract duration                                                                       |           | 1 month        |    |
| Maximum                                                                                          |           |           |    |
| **Disaggregation of Revenue [Line Items]**                                                       |           |           |    |
| Warranty contract duration                                                                       |           | 10 years       |    |
| Capitalized Commission Costs                                                                     |           |           |    |
| **Disaggregation of Revenue [Line Items]**                                                       |           |           |    |
| Capitalized commission costs                                                                     | 2,400          | $ 2,400        |    |
| Capitalized Administrator Service Costs                                                          |           |           |    |
| **Disaggregation of Revenue [Line Items]**                                                       |           |           |    |
| Capitalized commission costs                                                                     | $ 22           | $ 22           |    |

| X                                                                                                                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Revenue, Contract Duration
+ References
No definition available.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
The amount of expense recognized in the current period for the periodic realization of capitalized fees that were paid to salespeople, distributors, brokers, and agents at the time of the conclusion of the sale. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.
+ References
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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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