Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Operating loss carryforwards	$ 2,249	$ 1,654
Tax credit carryforwards	1,083	941
Investment in partnership	160	381
Goodwill and other intangibles	143	117
Employee benefits	138	98
Property	127	137
Receivables	53	79
Inventory	51	91
Other	264	317
Total deferred income tax asset	4,268	3,815
Valuation allowances	(3,472)	(2,883)
Total deferred income tax asset after valuation allowance	796	932
Deferred tax liabilities:
Other	(29)	(29)
Total deferred income tax liability	(29)	(29)
Net deferred tax asset	$ 767	$ 903