Shareholder's Equity - Changes in AOCI Components (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Changes in balances of each component of AOCI, net of tax
Beginning balance	$ 5,941	$ 6,131	$ 5,911
OCI before reclassifications	(2,689)	(207)	459
Amounts reclassified from AOCI	81	(427)	(10)
Total other comprehensive income (loss), net of tax	(2,608)	(634)	449
Ending balance	3,613	5,941	6,131
Total AOCI
Changes in balances of each component of AOCI, net of tax
Beginning balance	259	893	444
Total other comprehensive income (loss), net of tax	(2,608)	(634)	449
Ending balance	(2,349)	259	893
Net Unrealized Gains (Losses) on Securities
Changes in balances of each component of AOCI, net of tax
Beginning balance	574	1,247	758
OCI before reclassifications	(2,579)	(230)	498
Amounts reclassified from AOCI	67	(443)	(9)
Total other comprehensive income (loss), net of tax	(2,512)	(673)	489
Ending balance	(1,938)	574	1,247
Net Unrealized Gains (Losses) on Derivatives
Changes in balances of each component of AOCI, net of tax
Beginning balance	4	5	6
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	(1)	(1)	(1)
Total other comprehensive income (loss), net of tax	(1)	(1)	(1)
Ending balance	3	4	5
Defined Benefit Plans
Changes in balances of each component of AOCI, net of tax
Beginning balance	(151)	(204)	(138)
OCI before reclassifications	61	36	(66)
Amounts reclassified from AOCI	15	17	0
Total other comprehensive income (loss), net of tax	76	53	(66)
Ending balance	(75)	(151)	(204)
Foreign Currency Translation
Changes in balances of each component of AOCI, net of tax
Beginning balance	(167)	(154)	(181)
OCI before reclassifications	(171)	(13)	27
Amounts reclassified from AOCI	0	0	0
Total other comprehensive income (loss), net of tax	(171)	(13)	27
Ending balance	(338)	(167)	(154)
Other
Changes in balances of each component of AOCI, net of tax
Beginning balance	(1)	(1)	(1)
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	0
Total other comprehensive income (loss), net of tax	0	0	0
Ending balance	$ (1)	$ (1)	$ (1)