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Investments - Available for sale fixed maturities (Details) - USD ($) $ in Millions | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2020 | Jun. 30, 2020 | Mar. 31, 2020 | Jan. 01, 2020 | Dec. 31, 2019
--- | --- | --- | --- | --- | --- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | $ 9,481 |  | $ 8,812 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 9 | $ 10 | 12 | $ 14 | $ 14 |  | $ 0
Available for sale (AFS) fixed maturities | 9,732 |  | 9,084 |  |  |  |
Total fixed maturities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 9,481 |  | 8,812 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 9 |  | 12 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 272 |  | 305 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (12) |  | (21) |  |  |  |
Available for sale (AFS) fixed maturities | 9,732 |  | 9,084 |  |  |  |
Total fixed maturities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 31,596 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 28 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 2,652 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (97) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 34,123 |  |  |  |
Total fixed maturities | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 260 |  | 284 |  |  |  |
Total fixed maturities | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 2,555 |  |  |  |
U.S. Government and government agencies |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 218 |  | 192 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 0 |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 4 |  | 6 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (1) |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities | 221 |  | 198 |  |  |  |
U.S. Government and government agencies | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 39 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 5 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 44 |  |  |  |
U.S. Government and government agencies | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 3 |  | 6 |  |  |  |
U.S. Government and government agencies | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 5 |  |  |  |
States, municipalities and political subdivisions |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 1,967 |  | 2,196 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 0 |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 93 |  | 116 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | 0 |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities | 2,060 |  | 2,312 |  |  |  |
States, municipalities and political subdivisions | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 3,053 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 370 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (2) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 3,421 |  |  |  |
States, municipalities and political subdivisions | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 93 |  | 116 |  |  |  |
States, municipalities and political subdivisions | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 368 |  |  |  |
Foreign government |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 206 |  | 172 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 0 |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 2 |  | 4 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | 0 |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities | 208 |  | 176 |  |  |  |
Foreign government | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 31 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 4 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 35 |  |  |  |
Foreign government | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 2 |  | 4 |  |  |  |
Foreign government | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 4 |  |  |  |
Residential MBS |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 747 |  | 859 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 0 |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 53 |  | 57 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (2) |  | (1) |  |  |  |
Available for sale (AFS) fixed maturities | 798 |  | 915 |  |  |  |
Residential MBS | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 1,953 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 3 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 194 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (4) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 2,140 |  |  |  |
Residential MBS | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 51 |  | 56 |  |  |  |
Residential MBS | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 190 |  |  |  |
Commercial MBS |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 127 |  | 89 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 0 |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 3 |  | 3 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | 0 |  | 0 |  |  |  |
Available for sale (AFS) fixed maturities | 130 |  | 92 |  |  |  |
Commercial MBS | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 659 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 0 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 40 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (1) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 698 |  |  |  |
Commercial MBS | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 3 |  | 3 |  |  |  |
Commercial MBS | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 39 |  |  |  |
Collateralized loan obligations |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 1,382 |  | 1,065 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 1 |  | 3 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 5 |  | 4 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (2) |  | (4) |  |  |  |
Available for sale (AFS) fixed maturities | 1,384 |  | 1,062 |  |  |  |
Collateralized loan obligations | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 3,491 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 10 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 23 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (13) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 3,491 |  |  |  |
Collateralized loan obligations | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 3 |  | 0 |  |  |  |
Collateralized loan obligations | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 10 |  |  |  |
Other asset-backed securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 2,341 |  | 2,040 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 7 |  | 7 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains | 29 |  | 27 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (4) |  | (13) |  |  |  |
Available for sale (AFS) fixed maturities | 2,359 |  | 2,047 |  |  |  |
Other asset-backed securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 5,098 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 11 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 142 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (53) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 5,176 |  |  |  |
Other asset-backed securities | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | 25 |  | 14 |  |  |  |
Other asset-backed securities | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | 89 |  |  |  |
Corporate and other |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost | 2,493 |  | 2,199 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses | 1 | $ 1 | 2 | $ 3 | $ 3 | $ 0 | $ 0
Fixed maturities, available for sale, gross unrealized, gains | 83 |  | 88 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses | (3) |  | (3) |  |  |  |
Available for sale (AFS) fixed maturities | 2,572 |  | 2,282 |  |  |  |
Corporate and other | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available for sale, amortized cost |  |  | 17,272 |  |  |  |
Fixed maturities, available for sale, allowance for expected credit losses |  |  | 4 |  |  |  |
Fixed maturities, available for sale, gross unrealized, gains |  |  | 1,874 |  |  |  |
Fixed maturities, available for sale, gross unrealized, losses |  |  | (24) |  |  |  |
Available for sale (AFS) fixed maturities |  |  | 19,118 |  |  |  |
Corporate and other | Debt Securities |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax | $ 80 |  | 85 |  |  |  |
Corporate and other | Debt Securities | Assets of discontinued annuity operations | Annuity subsidiaries |  |  |  |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |  |  |  |
Fixed maturities, available-for-sale securities, accumulated gross unrealized gain (loss), before tax |  |  | $ 1,850 |  |  |  |

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