Strategic Initiatives - Expected Charges (Details) - 2-year Restructuring Plan [Member] - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		$ 590	$ 590
Maximum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		56
Maximum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		14
Maximum [Member] | Global Banking and Markets [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		135
Maximum [Member] | Corporate Center [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax	[1]	385
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		520	$ 520
Minimum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		50
Minimum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		10
Minimum [Member] | Global Banking and Markets [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		115
Minimum [Member] | Corporate Center [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax	[1]	$ 345

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