Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 1,129	$ 539	$ 816
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) on investment securities	(336)	229	257
Net unrealized gains (losses) on other noninterest-bearing investments	3	1	(9)
Net unrealized holding gains (losses) on derivative instruments	(26)	76	33
Reclassification adjustment for decrease (increase) in interest income recognized in earnings on derivative instruments	(46)	(36)	5
Pension and post-retirement	0	12	7
Other comprehensive income (loss), net of tax	(405)	282	293
Comprehensive income	$ 724	$ 821	$ 1,109