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Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | $ 306 | $ (247) | $ 78
Realized - impairments |  | (19) | (19) | (73)
Total realized gains (losses) on securities |  | 287 | (266) | 5
Net of tax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | 242 | (195) | 51
Realized - impairments |  | (15) | (15) | (48)
Total realized gains (losses) on securities |  | 227 | (210) | 3
Change in unrealized |  | 779 | (536) | 436
Total pretax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | 306 | (247) | 78
Realized - impairments |  | (19) | (19) | (73)
Total realized gains (losses) on securities |  | 287 | (266) | 5
Change in unrealized |  | 986 | (679) | 441
Fixed maturities |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | 26 | 6 | 17
Realized - impairments |  | (29) | (26) | (20)
Total realized gains (losses) on securities |  | (3) | (20) | (3)
Change in unrealized |  | 1,821 | (1,181) | 532
Equity securities |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | 277 | (265) | 70
Realized - impairments |  | 0 | 0 | (64)
Total realized gains (losses) on securities |  | 277 | (265) | 6
Change in unrealized |  | 0 | 0 | 128
Mortgage loans and other investments |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | 3 | 1 | (6)
Realized - impairments |  | 0 | 0 | (4)
Total realized gains (losses) on securities |  | 3 | 1 | (10)
Change in unrealized |  | 0 | 0 | 0
Other, Including DPAC and reserves on annuities and long-term care |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments | [1] | 0 | 11 | (3)
Realized - impairments | [1] | 10 | 7 | 15
Total realized gains (losses) on securities | [1] | 10 | 18 | 12
Change in unrealized | [1] | (835) | 502 | (219)
Effects Of Tax Cuts And Jobs Act Of 2017 |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  |  |  | 0
Realized - impairments |  |  |  | 0
Total realized gains (losses) on securities |  |  |  | 0
Change in unrealized |  |  |  | 149
Other tax effects |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  |  |  | (27)
Realized - impairments |  |  |  | 25
Total realized gains (losses) on securities |  |  |  | (2)
Change in unrealized |  |  |  | (154)
Total tax effects |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized before impairments |  | (64) | 52 | (27)
Realized - impairments |  | 4 | 4 | 25
Total realized gains (losses) on securities |  | (60) | 56 | (2)
Change in unrealized |  | $ (207) | $ 143 | $ (5)
[1] | Primarily adjustments to deferred policy acquisition costs and reserves related to the annuity business.

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