Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 284	$ 680	$ 907	$ 1,129
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) on investment securities		66	(2,762)	(336)
Unrealized loss amortization associated with the securities transferred from AFS to HTM	$ (1,800)	208	40	0
Net unrealized gains (losses) on other noninterest-bearing investments		1	(2)	3
Net unrealized holding gains (losses) on derivative instruments		21	(330)	(26)
Reclassification adjustment for decrease (increase) in interest income recognized in earnings on derivative instruments		124	21	(46)
Pension and post-retirement		0	1	0
Other comprehensive income (loss), net of tax		420	(3,032)	(405)
Comprehensive income (loss)		$ 1,100	$ (2,125)	$ 724