Restructuring - Restructuring Expenses Included in Consolidated Statements of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 0	$ 50	$ 60
2018 Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring	(2)	(4)	60
2020 Real Estate Rationalization Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring	0	36	0
2020 MA Strategic Reorganization Restructuring Program
Restructuring Cost and Reserve [Line Items]
Restructuring	$ 2	$ 18	$ 0