Parent Company Financial Information - Statements of Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Dividend income:
Other income (loss)	$ 68	$ 74	$ 78
Provision (provision credit) for credit losses	(310)	503	45
Interest on term borrowings	72	64	53
Personnel expense	1,210	1,033	695
Income before income taxes	1,284	933	586
Income tax benefit	274	76	134
Equity in undistributed net income (loss) of subsidiaries:
Net income attributable to controlling interest	999	845	441
Parent Company
Dividend income:
Bank	770	180	345
Non-bank	0	0	1
Total dividend income	770	180	346
Other income (loss)	(26)	0	1
Total income	744	180	347
Provision (provision credit) for credit losses	0	0	(1)
Interest on term borrowings	31	39	31
Personnel expense	89	54	53
Total expense	120	93	83
Income before income taxes	624	87	264
Income tax benefit	(35)	(18)	(19)
Income before equity in undistributed net income of subsidiaries	659	105	283
Equity in undistributed net income (loss) of subsidiaries:
Bank	332	736	160
Non-bank	8	4	(2)
Net income attributable to controlling interest	$ 999	$ 845	$ 441