| **Liability for Future Policy Benefit (Details) - USD ($) $ in Millions**   | 3 Months Ended |          |
|-----------------------------------------------------------------------------|----------------|----------|
||
| **Net liability for future policy benefits:**                               |           |     |   |
| Net life policy reserves                                                    | $ 3,013        |     | $ 3,068 |
| Life policy reserves:                                                       |           |     |   |
| **Net liability for future policy benefits:**                               |           |     |   |
| Net life policy reserves                                                    | 1,571          |     | 1,597 |
| Term Life Insurance | Life policy reserves:                                 |           |     |   |
| **Present value of expected net premiums:**                                 |           |     |   |
| Balance, beginning of period                                                | 1,700          | $ 1,643  |   |
| Beginning balance at original discount rate                                 | 1,712          | 1,708    |   |
| Effect of changes in cash flow assumptions                                  | 0              | 0        |   |
| Effect of changes in cash flow assumptions                                  | (9)            | (3)      |   |
| Adjusted beginning of period balance                                        | 1,703          | 1,705    |   |
| Issuances                                                                   | 35             | 38       |   |
| Interest accrual                                                            | 18             | 18       |   |
| Net premiums collected                                                      | (46)           | (46)     |   |
| Ending balance at original discount rate                                    | 1,710          | 1,715    |   |
| Effect of changes in discount rate assumptions                              | (50)           | (16)     |   |
| Balance, end of period                                                      | 1,660          | 1,699    |   |
| **Present value of expected future policy benefits:**                       |           |     |   |
| Balance, beginning of period                                                | 2,751          | 2,584    |   |
| Effect of changes in cash flow assumptions                                  | 2,765          | 2,692    |   |
| Effect of changes in cash flow assumptions                                  | 0              | 0        |   |
| Effect of changes in cash flow assumptions                                  | (14)           | (2)      |   |
| Adjusted beginning of period balance                                        | 2,751          | 2,690    |   |
| Issuances                                                                   | 35             | 38       |   |
| Interest accrual                                                            | 31             | 30       |   |
| Benefits paid                                                               | (37)           | (46)     |   |
| Ending balance at original discount rate                                    | 2,780          | 2,712    |   |
| Effect of changes in discount rate assumptions                              | (82)           | (21)     |   |
| Balance, end of period                                                      | 2,698          | 2,691    |   |
| **Net liability for future policy benefits:**                               |           |     |   |
| Present value of expected future policy benefits less expected net premiums | 1,038          | 992      |   |
| Impact of flooring at cohort level                                          | 16             | 19       |   |
| Net life policy reserves                                                    | 1,054          | 1,011    | 1,066 |
| Less reinsurance recoverable at original discount rate                      | (100)          | (96)     |   |
| Less effect of discount rate assumption changes on reinsurance recoverable  | (8)            | (10)     |   |
| Net life policy reserves, after reinsurance recoverable                     | $ 946          | $ 905    |   |
| Weighted-average duration of the net life policy reserves in years          | 11 years       | 12 years |   |
| Whole Life Insurance | Life policy reserves:                                |           |     |   |
| **Present value of expected net premiums:**                                 |           |     |   |
| Balance, beginning of period                                                | $ 223          | $ 208    |   |
| Beginning balance at original discount rate                                 | 225            | 217      |   |
| Effect of changes in cash flow assumptions                                  | 0              | 0        |   |
| Effect of changes in cash flow assumptions                                  | 0              | 1        |   |
| Adjusted beginning of period balance                                        | 225            | 218      |   |
| Issuances                                                                   | 5              | 7        |   |
| Interest accrual                                                            | 2              | 2        |   |
| Net premiums collected                                                      | (7)            | (7)      |   |
| Ending balance at original discount rate                                    | 225            | 220      |   |
| Effect of changes in discount rate assumptions                              | (6)            | (3)      |   |
| Balance, end of period                                                      | 219            | 217      |   |
| **Present value of expected future policy benefits:**                       |           |     |   |
| Balance, beginning of period                                                | 657            | 614      |   |
| Effect of changes in cash flow assumptions                                  | 628            | 607      |   |
| Effect of changes in cash flow assumptions                                  | 0              | 0        |   |
| Effect of changes in cash flow assumptions                                  | 0              | 1        |   |
| Adjusted beginning of period balance                                        | 628            | 608      |   |
| Issuances                                                                   | 5              | 6        |   |
| Interest accrual                                                            | 8              | 8        |   |
| Benefits paid                                                               | (8)            | (8)      |   |
| Ending balance at original discount rate                                    | 633            | 614      |   |
| Effect of changes in discount rate assumptions                              | 4              | 30       |   |
| Balance, end of period                                                      | 637            | 644      |   |
| **Net liability for future policy benefits:**                               |           |     |   |
| Present value of expected future policy benefits less expected net premiums | 418            | 427      |   |
| Impact of flooring at cohort level                                          | 0              | 0        |   |
| Net life policy reserves                                                    | 418            | 427      | $ 434 |
| Less reinsurance recoverable at original discount rate                      | (24)           | (25)     |   |
| Less effect of discount rate assumption changes on reinsurance recoverable  | (4)            | (6)      |   |
| Net life policy reserves, after reinsurance recoverable                     | $ 390          | $ 396    |   |
| Weighted-average duration of the net life policy reserves in years          | 16 years       | 16 years |   |

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| - Definition
Liability for Future Policy Benefit, before Impact of Flooring at Cohort Level, Before Reinsurance
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| - Definition
Net Liability for Future Policy Benefits
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| - Definition
Amount, before tax, of accumulated other comprehensive income (loss) (AOCI) from (increase) decrease in expected future policy benefit component of liability for future policy benefit from change in discount rate.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before tax, of accumulated other comprehensive income (loss) (AOCI) from increase (decrease) in expected net premium component of liability for future policy benefit from change in discount rate.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after effect of reinsurance, of liability for future policy benefit.
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| - Definition
Amount, before effect of reinsurance and after current period update of cash flow assumption, of expected future benefit and expense component for liability for future policy benefit, discounted at original rate.
+ References
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| - Definition
Amount, before effect of reinsurance and after current period update of cash flow assumption and discount rate change, of expected future policy benefit and expense component of liability for future policy benefit.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cumulative increase (decrease) in expected future policy benefit and expense component for liability of future policy benefit from cash flow assumption change for future cash flows.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cumulative increase (decrease) in expected future policy benefit and expense component for liability of future policy benefit from effect of variance from cash flow assumption change for actual experience.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of interest expense for expected future policy benefit and expense component of liability for future policy benefit.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in expected future policy benefit and expense component of liability for future policy benefit from contract issuance.
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| - Definition
Amount, before effect of reinsurance and current period update of cash flow assumption, of expected future policy benefit and expense component of liability for future policy benefit, discounted at original rate.
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| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
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| - Definition
Amount, before effect of reinsurance and after current period update of cash flow assumption and discount rate change, of expected net premium component of liability for future policy benefit.
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cumulative increase (decrease) in expected net premium component of liability for future policy benefit from cash flow assumption change for future cash flows.
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cumulative increase (decrease) in expected net premium component for liability of future policy benefit from effect of variance from cash flow assumption change for actual experience.
+ References
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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of interest income for expected net premium component of liability for future policy benefit.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of increase in expected net premium component of liability for future policy benefit from contract issuance.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of premium collected from policyholder to fund expected benefit payment for expected net premium component of liability for future policy benefit.
+ References
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of reinsurance and current period update of cash flow assumption, of expected net premium component of liability for future policy benefit, discounted at original rate.
+ References
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|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of reinsurance and after current period update of cash flow assumption, of expected net premium component for liability for future policy benefit, discounted at original rate.
+ References
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| - Definition
A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.
+ References
No definition available.
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, after allowance for credit loss, recoverable under reinsurance of liability for future policy benefit.
+ References
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|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Weighted-average duration of liability for future policy benefit, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount, before effect of reinsurance, of present value of future benefit to be paid to or on behalf of policyholder and related expense less present value of future net premium receivable under insurance contract.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cash outflow to policyholder from benefit payment for expected future policy benefit and expense component of liability for future policy benefit.
+ References
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