Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and allowance roll forward
Beginning balance, January 1	$ 6	$ 6
Ending balance, December 31	49	6	$ 6
Allowance for doubtful receivables
Valuation and allowance roll forward
Beginning balance, January 1	6	6	5
Additions charged to costs and expenses	8	6	6
Deductions	(6)	(6)	(5)
Ending balance, December 31	8	6	6
Deferred tax valuation allowance
Valuation and allowance roll forward
Beginning balance, January 1	0	0	0
Additions charged to costs and expenses	55	0	0
Deductions	(14)	0	0
Ending balance, December 31	$ 41	$ 0	$ 0