Loans and Allowance for Credit Losses, Nonaccrual (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Residential real estate [Member]
Nonaccrual Loans [Abstract]
Mortgage loans in process of foreclosure, amount	$ 3,700	$ 4,600
Government guaranteed mortgage loans upon foreclosure receivable [Member]
Nonaccrual Loans [Abstract]
Mortgage loans in process of foreclosure, amount	2,900	3,200
Non-PCI [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	5,922	6,496
Non-PCI [Member] | Total Commercial [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	2,470	2,188
Non-PCI [Member] | Commercial and industrial loans [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	1,634	1,486
Non-PCI [Member] | Commercial real estate mortgage [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	737	580
Non-PCI [Member] | Commercial real estate construction [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	36	32
Non-PCI [Member] | Commercial lease financing receivable [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	63	90
Non-PCI [Member] | Total Consumer [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	3,452	4,308
Non-PCI [Member] | Real estate 1-4 family first mortgage [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	2,425	3,183
Non-PCI [Member] | Real estate 1-4 family junior lien mortgage [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	868	945
Non-PCI [Member] | Automobile [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	115	130
Non-PCI [Member] | Other revolving credit and installment [Member]
Nonaccrual Loans [Abstract]
Nonaccrual loans	$ 44	$ 50