Fee-Based Revenue from Contracts with Customers - Asset Management Group 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
Asset Management Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	228	$ 220	676	$ 655
Asset Management Group [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	226		668
Asset Management Group [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	2		8
Asset Management Group [Member] | Personal [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	156		462
Asset Management Group [Member] | Institutional [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 70		$ 206