Fee-based Revenue from Contracts with Customers - Retail Banking Noninterest Income Disaggregation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Number of reportable segments | segment	3
Disaggregation of Revenue [Line Items]
Noninterest income	$ 6,955	$ 6,874	$ 6,469
Retail Banking
Disaggregation of Revenue [Line Items]
Noninterest income	2,519	2,648	2,631
Retail Banking | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	1,910	2,190	2,158
Retail Banking | Out-of-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	609	458	473
Retail Banking | Debit card fees | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	522	535	505
Retail Banking | Deposit account fees | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	463	642	618
Retail Banking | Brokerage fees | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	367	356	350
Retail Banking | Net credit card fees | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	179	186	189
Interchange Fees	469	498	452
Credit card reward costs	290	312	263
Retail Banking | Merchant services | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	154	216	212
Retail Banking | Other | In-Scope Retail Banking Noninterest Income
Disaggregation of Revenue [Line Items]
Noninterest income	$ 225	$ 255	$ 284