Shareholders' Equity - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended | |
Jun. 30, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023 | Dec. 31, 2022 |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | $ 16,998 | $ 15,314 | $ 16,525 | $ 15,201 | |
Other comprehensive income (loss) before reclassifications, after tax | 8 | (136) | 78 | 126 | |
Reclassification of losses from accumulated other comprehensive loss, after tax | 16 | 27 | 47 | 54 | |
Other comprehensive income (loss) | 24 | (109) | 125 | 180 | |
Amounts attributable to noncontrolling interests | (3) | 11 | (11) | (20) | |
Other | (3) | | 0 | | |
Balance at end of period | 17,201 | 15,470 | 17,201 | 15,470 | |
Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (277) | |
As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | 15,478 | |
Net Unrealized Gains (Losses) on Investments with an Allowance for Credit Losses | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (9) | (14) | (12) | (7) | |
Other comprehensive income (loss) before reclassifications, after tax | (4) | (8) | (5) | (16) | |
Reclassification of losses from accumulated other comprehensive loss, after tax | 4 | 7 | 7 | 7 | |
Other comprehensive income (loss) | 0 | (1) | 2 | (9) | |
Amounts attributable to noncontrolling interests | | (1) | | | |
Other | (1) | | | | |
Balance at end of period | (10) | (16) | (10) | (16) | |
Other comprehensive income (loss) before reclassifications, tax | 1 | 2 | 1 | 4 | |
Reclassification of losses from accumulated other comprehensive loss, tax | (1) | (2) | (2) | (2) | |
Net Unrealized Gains (Losses) on Investments with an Allowance for Credit Losses | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | $ 0 |
Net Unrealized Gains (Losses) on Investments with an Allowance for Credit Losses | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (7) | |
Net Unrealized Gains (Losses) on Other Investments | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (1,676) | (1,867) | (1,483) | (2,469) | |
Other comprehensive income (loss) before reclassifications, after tax | (250) | (427) | (489) | 225 | |
Reclassification of losses from accumulated other comprehensive loss, after tax | 6 | 14 | 28 | 32 | |
Other comprehensive income (loss) | (244) | (413) | (461) | 257 | |
Amounts attributable to noncontrolling interests | 19 | 42 | 38 | (26) | |
Other | (2) | | 3 | | |
Balance at end of period | (1,903) | (2,238) | (1,903) | (2,238) | |
Other comprehensive income (loss) before reclassifications, tax | 67 | 116 | 131 | (60) | |
Reclassification of losses from accumulated other comprehensive loss, tax | (1) | (4) | (7) | (8) | |
Net Unrealized Gains (Losses) on Other Investments | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | 0 |
Net Unrealized Gains (Losses) on Other Investments | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (2,469) | |
Cumulative impact of changes in discount rates used to measure long duration contracts | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (17) | (393) | (329) | (36) | |
Other comprehensive income (loss) before reclassifications, after tax | 273 | 256 | 614 | (140) | |
Reclassification of losses from accumulated other comprehensive loss, after tax | | | | | |
Other comprehensive income (loss) | 273 | 256 | 614 | (140) | |
Amounts attributable to noncontrolling interests | (22) | (26) | (51) | 13 | |
Other | | | | | |
Balance at end of period | 234 | (163) | 234 | (163) | |
Other comprehensive income (loss) before reclassifications, tax | (72) | (68) | (163) | 37 | |
Reclassification of losses from accumulated other comprehensive loss, tax | 0 | 0 | 0 | 0 | |
Cumulative impact of changes in discount rates used to measure long duration contracts | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (36) | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | 11 |
Cumulative impact of changes in discount rates used to measure long duration contracts | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | 0 | |
Unrealized Gains (Losses) on Cash Flow Hedges | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | 10 | 12 | 9 | 14 | |
Other comprehensive income (loss) before reclassifications, after tax | (1) | 8 | 1 | 6 | |
Reclassification of losses from accumulated other comprehensive loss, after tax | | | | | |
Other comprehensive income (loss) | (1) | 8 | 1 | 6 | |
Amounts attributable to noncontrolling interests | | | | | |
Other | 1 | | | | |
Balance at end of period | 10 | 20 | 10 | 20 | |
Other comprehensive income (loss) before reclassifications, tax | 1 | 0 | 0 | 1 | |
Reclassification of losses from accumulated other comprehensive loss, tax | 0 | 0 | 0 | 0 | |
Unrealized Gains (Losses) on Cash Flow Hedges | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | 0 |
Unrealized Gains (Losses) on Cash Flow Hedges | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | 14 | |
Pension and Postretirement Benefits | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (530) | (614) | (533) | (622) | |
Other comprehensive income (loss) before reclassifications, after tax | | | | | |
Reclassification of losses from accumulated other comprehensive loss, after tax | 6 | 6 | 12 | 15 | |
Other comprehensive income (loss) | 6 | 6 | 12 | 15 | |
Amounts attributable to noncontrolling interests | | (1) | (1) | (2) | |
Other | (1) | | (3) | | |
Balance at end of period | (525) | (609) | (525) | (609) | |
Other comprehensive income (loss) before reclassifications, tax | 0 | 0 | 0 | 0 | |
Reclassification of losses from accumulated other comprehensive loss, tax | (1) | (2) | (2) | (4) | |
Pension and Postretirement Benefits | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | 0 |
Pension and Postretirement Benefits | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (622) | |
Foreign Currency Translation | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (179) | (186) | (149) | (200) | |
Other comprehensive income (loss) before reclassifications, after tax | (10) | 35 | (43) | 51 | |
Reclassification of losses from accumulated other comprehensive loss, after tax | | | | | |
Other comprehensive income (loss) | (10) | 35 | (43) | 51 | |
Amounts attributable to noncontrolling interests | | (3) | 3 | (5) | |
Other | | | | | |
Balance at end of period | (189) | (154) | (189) | (154) | |
Other comprehensive income (loss) before reclassifications, tax | 0 | 0 | 0 | 0 | |
Reclassification of losses from accumulated other comprehensive loss, tax | 0 | 0 | 0 | 0 | |
Foreign Currency Translation | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | | |
Cumulative effect adjustments from changes in accounting standards, tax | | | | | $ 0 |
Foreign Currency Translation | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (200) | |
Total Accumulated Other Comprehensive Income (Loss) | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | (2,401) | (3,062) | (2,497) | (3,320) | |
Balance at end of period | $ (2,383) | $ (3,160) | $ (2,383) | (3,160) | |
Total Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjustment | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | (36) | |
Total Accumulated Other Comprehensive Income (Loss) | As Reported | | | | | |
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] | | | | | |
Balance at beginning of period | | | | $ (3,284) | |