Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Consolidated Balance Sheet [Abstract]
Allowance for accounts and notes receivable	$ 4	$ 13
Accumulated depreciation, depletion and amortization	$ 58,726	$ 55,477
Common stock, shares authorized	2,500,000,000	2,500,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares issued	1,798,738,512	1,795,652,203
Treasury stock, shares	725,996,869	710,783,814