Fee-based Revenue from Contracts with Customers - Asset Management Group Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Noninterest income	$ 6,955	$ 6,874	$ 6,469
Asset Management Group
Disaggregation of Revenue [Line Items]
Noninterest income	854	991	892
Asset Management Group | In-Scope Asset Management Group Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	836	862	883
Asset Management Group | Out-of-Scope Asset Management Group Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	18	129	9
Asset Management Group | Personal | In-Scope Asset Management Group Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	634	620	611
Asset Management Group | Institutional | In-Scope Asset Management Group Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	$ 202	$ 242	$ 272