Cost Reduction Programs and Other Charges - Summary of Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Restructuring Cost and Reserve [Line Items]
Balance, December 31, 2019			$ 200
2020 Cost Reduction Programs and Other Charges	$ 249	$ 141	380	$ 230
Less: Cash payments			(114)
Less: Non-cash charges			(88)
Foreign currency translation and other			4
Balance, June 30, 2020	382		382
Severance costs
Restructuring Cost and Reserve [Line Items]
2020 Cost Reduction Programs and Other Charges		$ 76		$ 109
Merger-related and other charges
Restructuring Cost and Reserve [Line Items]
Balance, December 31, 2019			67
2020 Cost Reduction Programs and Other Charges			89
Less: Cash payments			(37)
Less: Non-cash charges			(64)
Foreign currency translation and other			2
Balance, June 30, 2020	57		57
Cost Reduction Program
Restructuring Cost and Reserve [Line Items]
Balance, December 31, 2019			133
2020 Cost Reduction Programs and Other Charges	213		291
Less: Cash payments			(77)
Less: Non-cash charges			(24)
Foreign currency translation and other			2
Balance, June 30, 2020	325		325
Cost Reduction Program | Severance costs
Restructuring Cost and Reserve [Line Items]
Balance, December 31, 2019			117
2020 Cost Reduction Programs and Other Charges	192		250
Less: Cash payments			(64)
Less: Non-cash charges			0
Foreign currency translation and other			1
Balance, June 30, 2020	304		304
Cost Reduction Program | Other cost reduction charges
Restructuring Cost and Reserve [Line Items]
Balance, December 31, 2019			16
2020 Cost Reduction Programs and Other Charges	21		41
Less: Cash payments			(13)
Less: Non-cash charges			(24)
Foreign currency translation and other			1
Balance, June 30, 2020	$ 21		$ 21