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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,549	$ 1,717	$ 3,374	$ 3,303
Corporate & Institutional Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	726	661	1,420	1,237
Corporate & Institutional Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	446	404	883	772
Corporate & Institutional Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	280	257	537	465
Corporate & Institutional Banking [Member] | Treasury Management Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	218	212	434	411
Corporate & Institutional Banking [Member] | Capital Markets Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	187	149	362	276
Corporate & Institutional Banking [Member] | Commercial Mortgage Banking Activities [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	24	24	50	49
Corporate & Institutional Banking [Member] | Other | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 17	$ 19	$ 37	$ 36