Accumulated Other Comprehensive Income Loss - AOCI Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 13,676	$ 17,805
Other comprehensive income (loss), net of tax	587	(1,838)
Ending balance	14,340	15,890
AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-sale, Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(2,594)	1,631
OCI before reclassifications	715	(2,482)
Amounts reclassified from AOCI	27	87
OCI, before tax	742	(2,395)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(156)	503
Other comprehensive income (loss), net of tax	586	(1,892)
Ending balance	(2,008)	(261)
AOCI, Gain (Loss), Debt Securities, Available-for-sale, with Allowance for Credit Loss, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(7)	(2)
OCI before reclassifications	(8)	0
Amounts reclassified from AOCI	0	0
OCI, before tax	(8)	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	2	0
Other comprehensive income (loss), net of tax	(6)	0
Ending balance	(13)	(2)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	40	6
OCI before reclassifications	7	7
Amounts reclassified from AOCI	3	(8)
OCI, before tax	10	(1)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(2)	0
Other comprehensive income (loss), net of tax	8	(1)
Ending balance	48	5
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	31	41
OCI before reclassifications	3	0
Amounts reclassified from AOCI	0	0
OCI, before tax	3	0
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(1)	0
Other comprehensive income (loss), net of tax	2	0
Ending balance	33	41
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(1,346)	(1,489)
OCI before reclassifications	0	0
Amounts reclassified from AOCI	6	15
OCI, before tax	6	15
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(1)	(3)
Other comprehensive income (loss), net of tax	5	12
Ending balance	(1,341)	(1,477)
AOCI Attributable to Parent [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(3,841)	128
OCI before reclassifications	707	(2,421)
Amounts reclassified from AOCI	36	94
OCI, before tax	743	(2,327)
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(156)	489
Other comprehensive income (loss), net of tax	587	(1,838)
Ending balance	(3,254)	(1,710)
Liability for Future Policy Benefits Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	35	(59)
OCI before reclassifications	(10)	54
Amounts reclassified from AOCI	0	0
OCI, before tax	(10)	54
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	2	(11)
Other comprehensive income (loss), net of tax	(8)	43
Ending balance	$ 27	$ (16)