| **Future Policy Benefit Reserves - Undiscounted Expected Future Benefit and Expense Payments and Undiscounted Expected Future Gross Premiums (Details) - USD ($) $ in Millions** | Jun. 30, 2023 | Jun. 30, 2022 |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Insurance [Abstract]**                                                                                                                                                         |          |          |
| Expected future benefit and expense payments                                                                                                                                     | $ 33,287      | $ 33,429      |
| Expected future gross premiums                                                                                                                                                   | $ 5,536       | $ 5,848       |

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| - References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
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| - 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/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 29E -Publisher FASB -URI https://asc.fasb.org//1943274/2147480046/944-40-55-29EReference 2: 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//1943274/2147480081/944-40-50-6
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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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