Schedule II (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Accounts Receivable, Allowance for Credit Loss (beginning balance)	$ 74	$ 68	$ 68
Cumulative effect adjustment for adoption of ASC 2016-13	10
Net (credits) charges to expenses	49	23	19
Utilization of allowances	(27)	(17)	(19)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	0	0	(30)
Accounts Receivable, Allowance for Credit Loss (ending balance)	$ 105	$ 74	68
SEC Schedule, 12-09, Valuation Allowances and Reserves, Amount			$ 68	$ 98