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 and estimated returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance of valuation allowance and reserves	$ 76	$ 82	$ 77
Charged to Costs and Expenses, additions	16	6	15
Other, additions	0	0	0
Deductions	3	12	10
Ending balance of valuation allowance and reserves	89	76	82
Valuation allowance for deferred tax assets
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance of valuation allowance and reserves	59	54	9
Charged to Costs and Expenses, additions	1	12	45
Other, additions	0	0	0
Deductions	49	7	0
Ending balance of valuation allowance and reserves	$ 11	$ 59	$ 54