| **Future Policy Benefits Reserves - Undiscounted Expected Future Benefit and Expense Payments and Undiscounted Expected Future Gross Premiums (Details) - USD ($) $ in Millions** | Jun. 30, 2024 | Jun. 30, 2023 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Insurance [Abstract]**                                                                                                                                                          |          |          |
| Expected future benefit and expense payments                                                                                                                                      | $ 32,212      | $ 33,287      |
| Expected future gross premiums                                                                                                                                                    | $ 5,149       | $ 5,536       |

| X                                                                                                                                                                                           |
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| - References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of reinsurance, of undiscounted balance for expected future gross premium component of liability for future policy benefit.
+ References
Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-6Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29E -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-29E
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of reinsurance, of undiscounted balance for expected future policy benefit and expense component of liability for future policy benefit.
+ References
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