| **Investments (Credit quality indicator) (Details) - Mortgage loans $ in Millions** | Mar. 31, 2022 USD ($) |
|-------------------------------------------------------------------------------------|-----------------------|
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | $ 39                  |
| 2021                                                                                | 95                    |
| 2020                                                                                | 151                   |
| 2019                                                                                | 237                   |
| 2018                                                                                | 64                    |
| Prior                                                                               | 372                   |
| Total                                                                               | 958                   |
| DSCR ≥1.6x | LTV less than 55%                                                |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 9                     |
| 2020                                                                                | 94                    |
| 2019                                                                                | 21                    |
| 2018                                                                                | 54                    |
| Prior                                                                               | 247                   |
| Total                                                                               | 425                   |
| DSCR ≥1.6x | LTV 55% to 65%                                                   |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 5                     |
| 2020                                                                                | 19                    |
| 2019                                                                                | 8                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 24                    |
| Total                                                                               | 56                    |
| 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                                                                                | 0                     |
| 2021                                                                                | 13                    |
| 2020                                                                                | 14                    |
| 2019                                                                                | 95                    |
| 2018                                                                                | 10                    |
| Prior                                                                               | 56                    |
| Total                                                                               | 188                   |
| DSCR 1.2x - 1.6x | LTV 55% to 65%                                                   |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 21                    |
| 2021                                                                                | 36                    |
| 2020                                                                                | 24                    |
| 2019                                                                                | 0                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 8                     |
| Total                                                                               | 89                    |
| 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                                                                                | 52                    |
| 2018                                                                                | 0                     |
| Prior                                                                               | 30                    |
| Total                                                                               | 82                    |
| DSCR ≤1.2 | LTV 55% to 65%                                                    |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 0                     |
| 2020                                                                                | 0                     |
| 2019                                                                                | 55                    |
| 2018                                                                                | 0                     |
| Prior                                                                               | 0                     |
| Total                                                                               | 55                    |
| DSCR ≤1.2 | LTV greater than 65%                                              |                  |
| **Debt Securities, Available-for-sale [Line Items]**                                |                  |
| 2022                                                                                | 0                     |
| 2021                                                                                | 21                    |
| 2020                                                                                | 0                     |
| 2019                                                                                | 6                     |
| 2018                                                                                | 0                     |
| Prior                                                                               | 7                     |
| Total                                                                               | $ 34                  |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount excluding accrued interest, before allowance for credit loss, of financing receivable.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount excluding accrued interest of financing receivable originated more than five years prior to current fiscal year.
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| - Definition
Amount excluding accrued interest of financing receivable originated four years prior to current fiscal year.
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount excluding accrued interest of financing receivable originated three years prior to current fiscal year.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount excluding accrued interest of financing receivable originated in current fiscal year.
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| - Definition
Amount excluding accrued interest of financing receivable originated two years prior to current fiscal year.
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| - Definition
Amount excluding accrued interest of financing receivable originated in fiscal year prior to current fiscal year.
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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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