Fee-Based Revenue from Contracts with Customers - Retail Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,891	$ 1,780	$ 5,552	$ 5,306
Retail Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	622	$ 643	1,935	$ 1,891
Retail Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	548		1,594
Retail Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	74		341
Retail Banking [Member] | Deposit Account Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	162		451
Retail Banking [Member] | Debit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	130		374
Retail Banking [Member] | Brokerage Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	86		260
Retail Banking [Member] | Merchant Services [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	54		156
Retail Banking [Member] | Net Credit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	45		139
Interchange Fees	115		332
Credit Card Reward Costs	(70)		(193)
Retail Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 71		$ 214