Other Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill	$ 4,531	$ 4,581
Segment Reporting Information [Line Items]
Gains on sale of nonstrategic properties	1,800	800
Company share of equity affiliates foreign currency effects	(45)	1	$ 344
Gain (loss) for impairments and other assets write-offs	900	2,900
Total financing interest and debt costs	902	753	495
Less: Capitalized interest	595	552	495
Interest and debt expense	307	201	0
Research and development expenses	433	476	601
Excess of replacement cost over the carrying value of inventories (LIFO method)	3,937	2,942	3,745
LIFO losses on inventory drawdowns included in earnings	(5)	(88)	(65)
Foreign currency effects	(446)	58	$ 769
Downstream
Segment Reporting Information [Line Items]
Gains on sale of nonstrategic properties	850	600
Gain (loss) for impairments and other assets write-offs		110
Upstream
Segment Reporting Information [Line Items]
Gains on sale of nonstrategic properties	950	$ 200
Unocal
Business Acquisition [Line Items]
Goodwill	$ 4,531