Fee-Based Revenue from Contracts with Customers - Asset Management Group 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
Asset Management Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	222	$ 217	448	$ 435
Asset Management Group [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	220		442
Asset Management Group [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	2		6
Asset Management Group [Member] | Personal [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	152		306
Asset Management Group [Member] | Institutional [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 68		$ 136