Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred tax liabilities
Properties, plant and equipment	$ 17,251	$ 20,159
Investments and other	5,372	4,943
Total deferred tax liabilities	22,623	25,102
Deferred tax assets
Foreign tax credits	(9,840)	(10,536)
Asset retirement obligations/environmental reserves	(4,329)	(5,328)
Employee benefits	(3,454)	(2,787)
Deferred credits	(1,083)	(1,373)
Tax loss carryforwards	(5,262)	(4,948)
Other accrued liabilities	(441)	(595)
Inventory	(662)	(505)
Operating leases	(1,211)	0
Miscellaneous	(2,796)	(3,481)
Total deferred tax assets	(29,078)	(29,553)
Deferred tax assets valuation allowance	15,965	15,973
Total deferred taxes, net	9,510	11,522
Classification of deferred taxes
Deferred charges and other assets	(4,178)	(4,399)
Noncurrent deferred income taxes	13,688	15,921
Total deferred income taxes, net	$ 9,510	$ 11,522