Fair Values - Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Investment securities:
Equity securities	$ 46	$ 48
Debt securities	1,329	1,192
Derivative, gross, assets	328	1,006
Total Assets	1,702	2,246
Liabilities
Derivatives, gross, liabilities	992	131
Total Liabilities	992	131
Level 1
Investment securities:
Equity securities	46	48
Debt securities	0	0
Derivative, gross, assets	0	0
Total Assets	46	48
Liabilities
Derivatives, gross, liabilities	0	0
Total Liabilities	0	0
Level 2
Investment securities:
Equity securities	0	0
Debt securities	1,248	1,115
Derivative, gross, assets	313	975
Total Assets	1,560	2,090
Liabilities
Derivatives, gross, liabilities	992	131
Total Liabilities	992	131
Level 3
Investment securities:
Equity securities	0	0
Debt securities	81	77
Derivative, gross, assets	15	31
Total Assets	96	108
Liabilities
Derivatives, gross, liabilities	0	0
Total Liabilities	$ 0	$ 0