Asset Quality - Post-Modification Outstanding Recorded Investment by Concession Type for Our Commercial Accruing and Nonaccruing TDRs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total commercial and consumer TDRs	$ 73	$ 186
Total loans	94,646	89,552
Commercial Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Extension of maturity date	11	15
Payment or covenant modification/deferment	11	99
Bankruptcy plan modification	0	6
Increase in new commitment or new money	8	0
Total	30	120
Total loans	68,032	66,310
Consumer Loans [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Interest rate reduction	14	28
Forgiveness of principal	0	0
Other	29	38
Total	43	66
Total loans	$ 26,614	$ 23,242