| **Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions** | Sep. 30, 2022 USD ($) |
|-------------------------------------------------------------------------------------|-----------------------|
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | $ 129                 |
| 2021                                                                                | 94                    |
| 2020                                                                                | 150                   |
| 2019                                                                                | 208                   |
| 2018                                                                                | 64                    |
| Prior                                                                               | 332                   |
| Total                                                                               | 977                   |
| DSCR ≥1.6x | LTV less than 55%                                                |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 9                     |
| 2021                                                                                | 13                    |
| 2020                                                                                | 112                   |
| 2019                                                                                | 29                    |
| 2018                                                                                | 54                    |
| Prior                                                                               | 275                   |
| Total                                                                               | 492                   |
| DSCR ≥1.6x | LTV 55% to 65%                                                   |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 0                     |
| 2020                                                                                | 0                     |
| 2019                                                                                | 0                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 0                     |
| DSCR ≥1.6x | LTV greater than 65%                                             |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 18                    |
| 2021                                                                                | 11                    |
| 2020                                                                                | 0                     |
| 2019                                                                                | 0                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 29                    |
| DSCR 1.2x - 1.6x | LTV less than 55%                                                |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 5                     |
| 2021                                                                                | 49                    |
| 2020                                                                                | 18                    |
| 2019                                                                                | 56                    |
| 2018                                                                                | 10                    |
| Prior                                                                               | 42                    |
| Total                                                                               | 180                   |
| DSCR 1.2x - 1.6x | LTV 55% to 65%                                                   |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 87                    |
| 2021                                                                                | 0                     |
| 2020                                                                                | 20                    |
| 2019                                                                                | 0                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 8                     |
| Total                                                                               | 115                   |
| DSCR 1.2x - 1.6x | LTV greater than 65%                                             |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 0                     |
| 2020                                                                                | 0                     |
| 2019                                                                                | 0                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 0                     |
| DSCR ≤1.2 | LTV less than 55%                                                 |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 0                     |
| 2020                                                                                | 0                     |
| 2019                                                                                | 57                    |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 57                    |
| DSCR ≤1.2 | LTV 55% to 65%                                                    |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 21                    |
| 2020                                                                                | 0                     |
| 2019                                                                                | 44                    |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 65                    |
| DSCR ≤1.2 | LTV greater than 65%                                              |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 10                    |
| 2021                                                                                | 0                     |
| 2020                                                                                | 0                     |
| 2019                                                                                | 22                    |
| 2018                                                                                | 0                     |
| Prior                                                                               | 7                     |
| Total                                                                               | $ 39                  |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortized cost excluding accrued interest, of financing receivable originated more than five years prior to current fiscal year. Excludes net investment in lease.
+ References
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| - Definition
Amortized cost excluding accrued interest, of financing receivable originated four years prior to current fiscal year. Excludes net investment in lease.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortized cost excluding accrued interest, of financing receivable originated three years prior to current fiscal year. Excludes net investment in lease.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortized cost excluding accrued interest, of financing receivable originated in current fiscal year. Excludes net investment in lease.
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| - Definition
Amortized cost excluding accrued interest, of financing receivable originated two years prior to current fiscal year. Excludes net investment in lease.
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amortized cost excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year. Excludes net investment in lease.
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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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