Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 816	$ 884	$ 592
Other comprehensive income (loss), net of tax:
Net unrealized holding gains (losses) on investment securities	257	(113)	(2)
Net unrealized gains on other noninterest-bearing investments	(9)	2	3
Net unrealized holding gains (losses) on derivative instruments	33	(4)	(3)
Reclassification adjustment for increase in interest income recognized in earnings on derivative instruments	5	3	(2)
Pension and postretirement	(7)	(1)	(12)
Effect of new tax rates from Tax Cuts and Jobs Act of 2017	0	0	25
Other Comprehensive Income (Loss), Net of Tax	293	(111)	(17)
Comprehensive income	$ 1,109	$ 773	$ 575