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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Noninterest income	$ 1,941	$ 1,911	$ 3,752	$ 3,661
Corporate & Institutional Banking [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	661	635	1,237	1,182
Corporate & Institutional Banking [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	404	372	772	709
Corporate & Institutional Banking [Member] | Out-of-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	257	263	465	473
Corporate & Institutional Banking [Member] | Treasury Management Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	212	197	411	382
Corporate & Institutional Banking [Member] | Capital Markets Fees [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	149	135	276	250
Corporate & Institutional Banking [Member] | Commercial Mortgage Banking Activities [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	24	21	49	42
Corporate & Institutional Banking [Member] | Other [Member] | In-Scope [Member]
Disaggregation of Revenue [Line Items]
Noninterest income	$ 19	$ 19	$ 36	$ 35