Fair Values - Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Investment securities:
Equity securities	$ 66	$ 41
Debt securities	2,120	4,537
Derivatives, gross	80	521
Total Assets	2,266	5,099
Liabilities
Derivatives, gross	977	801
Total Liabilities	977	801
Fair Value, Inputs, Level 1
Investment securities:
Equity securities	66	40
Debt securities	0	0
Derivatives, gross	0	0
Total Assets	66	40
Liabilities
Derivatives, gross	0	0
Total Liabilities	0	0
Fair Value, Inputs, Level 2
Investment securities:
Equity securities	0	1
Debt securities	2,046	4,490
Derivatives, gross	62	494
Total Assets	2,108	4,985
Liabilities
Derivatives, gross	977	801
Total Liabilities	977	801
Fair Value, Inputs, Level 3
Investment securities:
Equity securities	0	0
Debt securities	74	47
Derivatives, gross	18	27
Total Assets	92	74
Liabilities
Derivatives, gross	0	0
Total Liabilities	$ 0	$ 0