Long-Term Debt And Shareholders' Equity (Amounts Reclassified from AOCI) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension and post-retirement
Interest and fees on loans	$ 505	$ 581	$ 1,551	$ 1,731
Income tax expense (benefit)	(40)	(66)	(58)	(185)
Net income	175	222	255	633
Net unrealized gains (losses) on derivatives and other | Amounts reclassified from AOCI
Pension and post-retirement
Interest and fees on loans	16	(1)	32	(4)
Income tax expense (benefit)	4	0	8	(1)
Net income	$ 12	$ (1)	$ 24	$ (3)