Shareholder's Equity - Changes in AOCI Components (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Changes in balances of each component of AOCI, net of tax
Beginning balance	$ 4,304	$ 5,686	$ 5,685	$ 5,867
OCI before reclassifications	(1,067)	36	(2,861)	(93)
Amounts reclassified from AOCI	68	(397)	64	(437)
Total other comprehensive income (loss), net of tax	(999)	(361)	(2,797)	(530)
Ending balance	3,257	5,707	3,257	5,707
Total AOCI
Changes in balances of each component of AOCI, net of tax
Beginning balance	(1,795)	460	3	629
Total other comprehensive income (loss), net of tax	(999)	(361)	(2,797)	(530)
Ending balance	(2,794)	99	(2,794)	99
Net Unrealized Gains (Losses) on Securities
Changes in balances of each component of AOCI, net of tax
Beginning balance	(1,311)	784	318	983
OCI before reclassifications	(941)	58	(2,566)	(101)
Amounts reclassified from AOCI	68	(397)	64	(437)
Total other comprehensive income (loss), net of tax	(873)	(339)	(2,502)	(538)
Ending balance	(2,184)	445	(2,184)	445
Net Unrealized Gains (Losses) on Derivatives
Changes in balances of each component of AOCI, net of tax
Beginning balance	3	5	4	5
OCI before reclassifications	0	0	(1)	0
Amounts reclassified from AOCI	0	0	0	0
Total other comprehensive income (loss), net of tax	0	0	(1)	0
Ending balance	3	5	3	5
Defined Benefit Plans
Changes in balances of each component of AOCI, net of tax
Beginning balance	(151)	(175)	(151)	(204)
OCI before reclassifications	1	0	1	29
Amounts reclassified from AOCI	0	0	0	0
Total other comprehensive income (loss), net of tax	1	0	1	29
Ending balance	(150)	(175)	(150)	(175)
Foreign Currency Translation
Changes in balances of each component of AOCI, net of tax
Beginning balance	(335)	(153)	(167)	(154)
OCI before reclassifications	(127)	(22)	(295)	(21)
Amounts reclassified from AOCI	0	0	0	0
Total other comprehensive income (loss), net of tax	(127)	(22)	(295)	(21)
Ending balance	(462)	(175)	(462)	(175)
Other
Changes in balances of each component of AOCI, net of tax
Beginning balance	(1)	(1)	(1)	(1)
OCI before reclassifications	0	0	0	0
Amounts reclassified from AOCI	0	0	0	0
Total other comprehensive income (loss), net of tax	0	0	0	0
Ending balance	$ (1)	$ (1)	$ (1)	$ (1)