Asset Quality - Post-Modification Outstanding Recorded Investment by Concession Type for Our Commercial Accruing and Nonaccruing TDRs (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total commercial and consumer TDRs	$ 18	$ 48	$ 34	$ 59
Commercial Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Extension of Maturity Date	8	6	8	6
Payment or Covenant Modification/Deferment	0	18	0	18
Bankruptcy Plan Modification	0	11	0	11
Increase in new commitment or new money	4	0	4	0
Total	12	35	12	35
Consumer Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Interest rate reduction	1	4	9	8
Other	5	9	13	16
Total	$ 6	$ 13	$ 22	$ 24