Schedule II Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 111	$ 113	$ 116
Additions, charged (credited) to income	30	13	21
Additions, charged (credited) to AOCL	0	0	0
Deductions from reserves	(11)	(14)	(19)
Translation adjustment during period	5	(1)	(5)
Balance at end of period	150	111	113
Allowance for doubtful accounts | Accounting Standards Update 2016-13 | Revision of Prior Period, Accounting Standards Update, Adjustment
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	126
Balance at end of period		126
Valuation allowance — deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	982	317	318
Additions, charged (credited) to income	488	661	18
Additions, charged (credited) to AOCL	(1)	4	(1)
Deductions from reserves	0	0	0
Translation adjustment during period	0	0	(18)
Balance at end of period	$ 1,469	$ 982	$ 317