Fee-Based Revenue from Contracts with Customers - Retail Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,911	$ 1,802	$ 3,661	$ 3,526
Retail Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	678	$ 645	1,313	$ 1,248
Retail Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	537		1,046
Retail Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	141		267
Retail Banking [Member] | Deposit Account Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	145		289
Retail Banking [Member] | Debit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	127		244
Retail Banking [Member] | Brokerage Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	88		174
Retail Banking [Member] | Merchant Services [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	55		102
Retail Banking [Member] | Net Credit Card Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Interchange Fees	115		217
Noninterest income	49		94
Credit Card Reward Costs	66		123
Retail Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 73		$ 143