Fee-Based Revenue from Contracts with Customers - Asset Management Group Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,872	$ 1,825
Asset Management Group
Disaggregation of Revenue [Line Items]
Noninterest income	229	204
Asset Management Group | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	226	201
Asset Management Group | Out-of-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	3	3
Asset Management Group | Personal | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	173	150
Asset Management Group | Institutional | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	$ 53	$ 51