Valuation And Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and allowance roll forward
Beginning balance, January 1	$ 49	$ 6
Ending balance, December 31	78	49	$ 6
Increase to allowance through retained earnings for ASU 2016-13, pretax		3	0	$ 0
Allowance for doubtful receivables
Valuation and allowance roll forward
Beginning balance, January 1	8	6	6
Additions charged to costs and expenses	19	8	6
Deductions	(8)	(6)	(6)
Ending balance, December 31	22	8	6
Deferred tax valuation allowance
Valuation and allowance roll forward
Beginning balance, January 1	41	0	0
Additions charged to costs and expenses	15	55	0
Deductions	0	(14)	0
Ending balance, December 31	$ 56	$ 41	$ 0