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, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,891	$ 1,780	$ 5,552	$ 5,306
Corporate & Institutional Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	592	$ 555	1,774	$ 1,667
Corporate & Institutional Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	382		1,091
Corporate & Institutional Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	210		683
Corporate & Institutional Banking [Member] | Treasury Management Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	196		578
Corporate & Institutional Banking [Member] | Capital Markets Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	147		397
Corporate & Institutional Banking [Member] | Commercial Mortgage Banking Activities [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	23		65
Corporate & Institutional Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 16		$ 51