Fee-Based Revenue from Contracts with Customers - Retail Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,750	$ 1,724
Retail Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	635	$ 603
Retail Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	509
Retail Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	126
Retail Banking [Member] | Deposit Account Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	144
Retail Banking [Member] | Debit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	117
Retail Banking [Member] | Brokerage Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	86
Retail Banking [Member] | Merchant Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	47
Retail Banking [Member] | Credit Card Fees, Net [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Interchange Fees	102
Noninterest income	45
Credit Card Reward Costs	57
Retail Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 70