Revenue from Contract with Customer (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenue from External Customer [Line Items]
Revenue, Percentage from Products and Services Transferred to Customers	98.00%	99.00%	99.00%	99.00%
Contract with Customer, Liability	$ 39		$ 39		$ 41
Accrued Liabilities [Member]
Revenue from External Customer [Line Items]
Contract with Customer, Liability, Current	3		3		4
Other Noncurrent Liabilities [Member]
Revenue from External Customer [Line Items]
Contract with Customer, Liability, Noncurrent	$ 36		$ 36		$ 37
Maximum [Member] | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-07-01
Revenue from External Customer [Line Items]
Revenue, Performance Obligation, Description of Timing	21 years		21 years