Strategic Initiatives - Expected Charges (Details) - 2-year Restructuring Plan [Member] - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		$ 480	$ 400
Maximum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		28
Maximum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		10
Maximum [Member] | Global Banking and Markets [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		110
Maximum [Member] | Corporate Center [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax	[1]	332
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		410	$ 350
Minimum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		24
Minimum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		8
Minimum [Member] | Global Banking and Markets [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		90
Minimum [Member] | Corporate Center [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax	[1]	$ 288

[1] Includes restructuring charges primarily related to lease impairment and other related costs, as well as severance costs associated with certain centralized activities and functions.