Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Employee benefits	$ 224	$ 208
Net operating loss carryforwards	1,484	1,261
Tax credit carryforwards	257	258
Other	242	241
Valuation allowances	(138)	(155)
Total deferred tax assets	2,069	1,813
Deferred tax liabilities
Property, plant and equipment	414	385
Investments	1,084	529
Other	35	42
Total deferred tax liabilities	1,533	956
Net deferred tax assets	$ 536	$ 857

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