Accumulated Other Comprehensive Income Loss - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 16,447
OCI, net of tax	306	$ (148)
Ending balance	16,844	15,468
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,539)	(1,482)
OCI before reclassifications	372	(210)
Amounts reclassified from AOCI	10	7
OCI, before tax	382	(203)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(80)	43
OCI, net of tax	302	(160)
Ending balance	(1,237)	(1,642)
AOCI, Gain (Loss), Debt Securities, Available-for-sale, with Allowance for Credit Loss, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(6)	(8)
OCI before reclassifications	0	1
Amounts reclassified from AOCI	0	0
OCI, before tax	0	1
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0	0
OCI, net of tax	0	1
Ending balance	(6)	(7)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	40	21
OCI before reclassifications	4	0
Amounts reclassified from AOCI	(4)	0
OCI, before tax	0	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0	0
OCI, net of tax	0	0
Ending balance	40	21
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	29	37
OCI before reclassifications	0	(1)
Amounts reclassified from AOCI	0	0
OCI, before tax	0	(1)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	0	0
OCI, net of tax	0	(1)
Ending balance	29	36
AOCI, Liability for Future Policy Benefit, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	33	25
OCI before reclassifications	(4)	6
Amounts reclassified from AOCI	0	0
OCI, before tax	(4)	6
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	1	(1)
OCI, net of tax	(3)	5
Ending balance	30	30
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,443)	(1,442)
OCI before reclassifications	2	2
Amounts reclassified from AOCI	7	7
OCI, before tax	9	9
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(2)	(2)
OCI, net of tax	7	7
Ending balance	(1,436)	(1,435)
AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(2,886)	(2,849)
OCI before reclassifications	374	(202)
Amounts reclassified from AOCI	13	14
OCI, before tax	387	(188)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(81)	40
OCI, net of tax	306	(148)
Ending balance	$ (2,580)	$ (2,997)

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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Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount before tax of other comprehensive income (loss) attributable to parent entity.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity.

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