Fee-Based Revenue from Contracts with Customers - Asset Management Group 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
Asset Management Group [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	226	$ 218
Asset Management Group [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	222
Asset Management Group [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	4
Asset Management Group [Member] | Personal [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	154
Asset Management Group [Member] | Institutional [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 68