Fee-Based Revenue from Contracts with Customers - Corporate & Institutional Banking Noninterest Income Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Noninterest income	$ 2,086	$ 1,549	$ 3,958	$ 3,374
Corporate & Institutional Banking
Disaggregation of Revenue [Line Items]
Noninterest income	867	726	1,674	1,420
Corporate & Institutional Banking | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	564	446	1,051	883
Corporate & Institutional Banking | Out-of-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	303	280	623	537
Corporate & Institutional Banking | Treasury management fees | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	279	218	514	434
Corporate & Institutional Banking | Capital markets fees | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	232	187	424	362
Corporate & Institutional Banking | Commercial mortgage banking activities | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	35	24	66	50
Corporate & Institutional Banking | Other | In-Scope
Disaggregation of Revenue [Line Items]
Noninterest income	$ 18	$ 17	$ 47	$ 37