Fee-Based Revenue from Contracts with Customers - Corporate & Institutional Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,797	$ 1,738	$ 5,171	$ 5,041
Corporate & Institutional Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	723	654	2,143	1,891
Corporate & Institutional Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	412	384	1,295	1,156
Corporate & Institutional Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	311	270	848	735
Corporate & Institutional Banking [Member] | Treasury Management Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	231	210	665	621
Corporate & Institutional Banking [Member] | Capital Markets Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	132	131	494	407
Corporate & Institutional Banking [Member] | Commercial Mortgage Banking Activities [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	31	26	81	75
Corporate & Institutional Banking [Member] | Other | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 18	$ 17	$ 55	$ 53