Strategic Initiatives - Expected Charges (Details) - Restructuring Plan [Member] - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		$ 900	$ 520
Minimum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		160
Minimum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		25
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]	600
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		1,000	$ 590
Maximum [Member] | Wealth and Personal Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		180
Maximum [Member] | Commercial Banking [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		35
Maximum [Member] | Global Banking and Markets [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax		130
Maximum [Member] | Corporate Center [Member]
Restructuring Cost and Reserve [Line Items]
Expected restructuring charges, pre-tax	[1]	$ 655

[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.