Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Trade accounts receivable
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 65	$ 71	$ 76
Charged to costs and expense	4	(6)	0
Charged to other accounts	0	(4)	6
Acquisitions	1	7	0
Deductions – write-offs	(8)	(3)	(11)
Balance at end of period	62	65	71
Deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	282	228	225
Charged to costs and expense	(33)	(1)	9
Charged to other accounts	5	(7)	0
Acquisitions	0	76	0
Deductions – write-offs	(11)	(14)	(6)
Balance at end of period	$ 243	$ 282	$ 228