Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for doubtful accounts receivable
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	$ 2
Charge to cost and expenses	0	$ 0
Charge to other accounts		2
Balance at the end of the period	2	2
Allowance for obsolete materials and supplies
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	143	127	$ 134
Charge to cost and expenses	43	25	3
Deductions	3	9	10
Balance at the end of the period	183	143	127
Valuation allowance on deferred tax assets
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	685	716	681
Charge to cost and expenses	1,167	(31)	37
Deductions	32		2
Balance at the end of the period	$ 1,820	$ 685	$ 716