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, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,911	$ 1,802	$ 3,661	$ 3,526
Corporate & Institutional Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	635	$ 588	1,182	$ 1,112
Corporate & Institutional Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	372		709
Corporate & Institutional Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	263		473
Corporate & Institutional Banking [Member] | Treasury Management Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	197		382
Corporate & Institutional Banking [Member] | Capital Markets Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	135		250
Corporate & Institutional Banking [Member] | Commercial Mortgage Banking Activities [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	21		42
Corporate & Institutional Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 19		$ 35