Restructuring and other (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring and other	$ 45	$ 17	$ 96	$ 48
Employee severance
Restructuring Cost and Reserve [Line Items]
Restructuring and other	3	7	3	28
Employee severance | Contingencies Related to COVID-19 [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other	6		28
Restructuring, integration and other(3)
Restructuring Cost and Reserve [Line Items]
Restructuring and other	11	10	36	20
Strategic Review and Related
Restructuring Cost and Reserve [Line Items]
Restructuring and other	$ 31	$ 0	$ 57	$ 0