Schedule II - Valuation and Qualifying Accounts - Summary of Valuation Allowance (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Beginning balance		$ 5	$ 5	$ 3
Charged to costs and expenses		11	2	3
Charged to other accounts		0	0	0
Deductions	[1]	(5)	(2)	(1)
Ending balance		11	5	5
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
Beginning balance		0	0	1
Charged to costs and expenses		14	0	(1)
Charged to other accounts		0	0	0
Deductions	[1]	0	0	0
Ending balance		$ 14	$ 0	$ 0

[1] Deductions from allowance for doubtful accounts represent write-offs of receivable balances not considered collectible. The deduction from the valuation allowance for deferred tax assets represents changes in estimates of our future taxable income and our estimated future usage of certain net operating loss carryforwards, as well as expiration of certain net operating loss carryforwards.