Condensed Consolidated Statement Of Changes In Equity - USD ($) shares in Millions, $ in Millions	Total	ExxonMobil Share Of Common Stock [Member]	ExxonMobil Share Of Earnings Reinvested [Member]	ExxonMobil Share Of Accumulated Other Comprehensive Income [Member]	ExxonMobil Share Of Common Stock Held In Treasury [Member]	ExxonMobil Share Of Equity [Member]	Noncontrolling Interests [Member]
Balance at Dec. 31, 2017	$ 194,500	$ 14,656	$ 414,540	$ (16,262)	$ (225,246)	$ 187,688	$ 6,812
Balance (in shares) - issued at Dec. 31, 2017	8,019
Balance (in shares) - in treasury at Dec. 31, 2017	(3,780)
Balance (in shares) - outstanding at Dec. 31, 2017	4,239
Amortization of stock-based awards	$ 605	605				605
Other	(15)	(7)				(7)	(8)
Net income for the period	15,215		14,840			14,840	375
Dividends - common shares (company)			(10,296)			(10,296)
Dividends - common shares (NCI)							(192)
Dividends - common shares (total)	(10,488)
Cumulative effect of accounting change	47		71	(39)		32	15
Other comprehensive income	(2,239)			(2,069)		(2,069)	(170)
Acquisitions, at cost (company)					$ (430)	(430)
Acquisitions, at cost (NCI)							(366)
Acquisitions, at cost (total)	$ (796)
Acquisitions (in shares)	(5)				(5)
Dispositions	$ 2				$ 2	2
Balance at Sep. 30, 2018	$ 196,831	15,254	419,155	(18,370)	(225,674)	190,365	6,466
Balance (in shares) - issued at Sep. 30, 2018	8,019
Balance (in shares) - in treasury at Sep. 30, 2018	(3,785)
Balance (in shares) - outstanding at Sep. 30, 2018	4,234
Balance at Jun. 30, 2018	$ 193,533	15,086	416,418	(18,609)	(225,673)	187,222	6,311
Balance (in shares) - issued at Jun. 30, 2018	8,019
Balance (in shares) - in treasury at Jun. 30, 2018	(3,785)
Balance (in shares) - outstanding at Jun. 30, 2018	4,234
Amortization of stock-based awards	$ 169	169				169
Other	(2)	(1)				(1)	(1)
Net income for the period	6,446		6,240			6,240	206
Dividends - common shares (company)			(3,503)			(3,503)
Dividends - common shares (NCI)							(57)
Dividends - common shares (total)	(3,560)
Other comprehensive income	344			239		239	105
Acquisitions, at cost (company)					(1)	(1)
Acquisitions, at cost (NCI)							(98)
Acquisitions, at cost (total)	(99)
Balance at Sep. 30, 2018	$ 196,831	15,254	419,155	(18,370)	(225,674)	190,365	6,466
Balance (in shares) - issued at Sep. 30, 2018	8,019
Balance (in shares) - in treasury at Sep. 30, 2018	(3,785)
Balance (in shares) - outstanding at Sep. 30, 2018	4,234
Balance at Dec. 31, 2018	$ 198,528	15,258	421,653	(19,564)	(225,553)	191,794	6,734
Balance (in shares) - issued at Dec. 31, 2018	8,019
Balance (in shares) - in treasury at Dec. 31, 2018	(3,782)
Balance (in shares) - outstanding at Dec. 31, 2018	4,237
Amortization of stock-based awards	$ 545	545				545
Other	267	(8)				(8)	275
Net income for the period	9,044		8,650			8,650	394
Dividends - common shares (company)			(10,936)			(10,936)
Dividends - common shares (NCI)							(157)
Dividends - common shares (total)	(11,093)
Other comprehensive income	480			287		287	193
Acquisitions, at cost (company)					$ (421)	(421)
Acquisitions, at cost (NCI)							(245)
Acquisitions, at cost (total)	$ (666)
Acquisitions (in shares)	(6)				(6)
Dispositions	$ 4				$ 4	4
Balance at Sep. 30, 2019	$ 197,109	15,795	419,367	(19,277)	(225,970)	189,915	7,194
Balance (in shares) - issued at Sep. 30, 2019	8,019
Balance (in shares) - in treasury at Sep. 30, 2019	(3,788)
Balance (in shares) - outstanding at Sep. 30, 2019	4,231
Balance at Jun. 30, 2019	$ 198,465	15,639	419,913	(18,205)	(225,970)	191,377	7,088
Balance (in shares) - issued at Jun. 30, 2019	8,019
Balance (in shares) - in treasury at Jun. 30, 2019	(3,788)
Balance (in shares) - outstanding at Jun. 30, 2019	4,231
Amortization of stock-based awards	$ 156	156				156
Other	275						275
Net income for the period	3,247		3,170			3,170	77
Dividends - common shares (company)			(3,716)			(3,716)
Dividends - common shares (NCI)							(57)
Dividends - common shares (total)	(3,773)
Other comprehensive income	(1,135)			(1,072)		(1,072)	(63)
Acquisitions, at cost (NCI)							(79)
Acquisitions, at cost (total)	(79)
Dispositions	(47)
Dispositions (NCI)							(47)
Balance at Sep. 30, 2019	$ 197,109	$ 15,795	$ 419,367	$ (19,277)	$ (225,970)	$ 189,915	$ 7,194
Balance (in shares) - issued at Sep. 30, 2019	8,019
Balance (in shares) - in treasury at Sep. 30, 2019	(3,788)
Balance (in shares) - outstanding at Sep. 30, 2019	4,231