Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net unrealized gains (losses) on securities available for sale, tax	$ 131	$ 309	$ (50)	$ 871
Net unrealized gains (losses) on derivative financial instruments, tax	49	82	(28)	259
Net pension and postretirement benefit costs, tax	$ (1)	$ (1)	$ (1)	$ (2)