Restructuring Costs - Summary of Total Restructuring Costs (Details) - Transformation Program [Member] - USD ($) $ in Millions	12 Months Ended			27 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2023
Restructuring Cost and Reserve [Line Items]
Total				$ 193
Real Estate Rationalization [Member]
Restructuring Cost and Reserve [Line Items]
Total	$ 46	$ 79	$ 19	144
Technology Modernization [Member]
Restructuring Cost and Reserve [Line Items]
Total	22	19	5	46
Process Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Total		1		1
Other [Member]
Restructuring Cost and Reserve [Line Items]
Total			2	2
Corporate, Non-Segment
Restructuring Cost and Reserve [Line Items]
Total				177
Corporate, Non-Segment | Real Estate Rationalization [Member]
Restructuring Cost and Reserve [Line Items]
Total	46	79	19	144
Corporate, Non-Segment | Technology Modernization [Member]
Restructuring Cost and Reserve [Line Items]
Total	15	16		31
Corporate, Non-Segment | Other [Member]
Restructuring Cost and Reserve [Line Items]
Total			2	2
HWC [Member]
Restructuring Cost and Reserve [Line Items]
Total				3
HWC [Member] | Technology Modernization [Member]
Restructuring Cost and Reserve [Line Items]
Total	2			2
HWC [Member] | Process Optimization [Member]
Restructuring Cost and Reserve [Line Items]
Total		1		1
R&B [Member]
Restructuring Cost and Reserve [Line Items]
Total				13
R&B [Member] | Technology Modernization [Member]
Restructuring Cost and Reserve [Line Items]
Total	$ 5	$ 3	$ 5	$ 13