Fee-Based Revenue from Contracts with Customers - Retail Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Noninterest income	$ 2,006	$ 1,811
Retail Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	788	595
Retail Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	526	523
Retail Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	262	72
Retail Banking [Member] | Deposit Account Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	158	148
Retail Banking [Member] | Debit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	129	124
Retail Banking [Member] | Brokerage Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	93	89
Retail Banking [Member] | Merchant Services [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	49	48
Retail Banking [Member] | Net Credit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	41	48
Interchange fees	118	112
Credit card reward costs	77	64
Retail Banking [Member] | Other | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 56	$ 66