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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Noninterest income	$ 2,341	$ 1,797	$ 6,299	$ 5,171
Corporate & Institutional Banking
Disaggregation of Revenue [Line Items]
Noninterest income	1,056	723	2,730	2,143
Corporate & Institutional Banking | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	730	412	1,781	1,295
Corporate & Institutional Banking | Out-of-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	326	311	949	848
Corporate & Institutional Banking | Treasury management fees | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	323	231	837	665
Corporate & Institutional Banking | Capital markets fees | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	354	132	778	494
Corporate & Institutional Banking | Commercial mortgage banking activities | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	36	31	102	81
Corporate & Institutional Banking | Other | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	$ 17	$ 18	$ 64	$ 55