Fair Values - Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Investment securities:
Equity securities	$ 66	$ 41
Debt securities	3,094
Derivative, gross, assets	594	521
Liabilities
Derivatives, gross, liabilities	301	801
Fair Value, Recurring
Investment securities:
Equity securities	66	41
Debt securities	3,094	4,537
Derivative, gross, assets	594	521
Total Assets	3,754	5,099
Liabilities
Derivatives, gross, liabilities	301	801
Total Liabilities	301	801
Level 1 | Fair Value, Recurring
Investment securities:
Equity securities	66	40
Debt securities	0	0
Derivative, gross, assets	0	0
Total Assets	66	40
Liabilities
Derivatives, gross, liabilities	0	0
Total Liabilities	0	0
Level 2 | Fair Value, Recurring
Investment securities:
Equity securities	0	1
Debt securities	3,030	4,490
Derivative, gross, assets	579	494
Total Assets	3,609	4,985
Liabilities
Derivatives, gross, liabilities	301	801
Total Liabilities	301	801
Level 3 | Fair Value, Recurring
Investment securities:
Equity securities	0	0
Debt securities	64	47
Derivative, gross, assets	15	27
Total Assets	79	74
Liabilities
Derivatives, gross, liabilities	0	0
Total Liabilities	$ 0	$ 0