Commitments and Contingencies (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2020	Feb. 29, 2020
Long-term Purchase Commitment [Line Items]
Unrecorded unconditional purchase obligation	$ 38			$ 44
Purchases in the period	6
Remaining commitment	38
Purchase obligation, fixed fee cap		$ 14
Purchase obligation, variable fee cap		39
Future contingent termination fees, period two		12
Future contingent termination fees, period three		14
Purchase Obligation, Fixed Fees Incurred	3	$ 2
Purchase Obligation, Variable Fees Incurred	$ 10
Unconditional purchase obligation, term	3 years
Forecast
Long-term Purchase Commitment [Line Items]
Unconditional purchase obligation for 2020			$ 8