Financial Instruments Long Term Debt (Details) - Exxon Mobil Corporation [Member] $ in Millions	6 Months Ended
Jun. 30, 2020 USD ($)
Debt Instrument [Line Items]
Long-term debt	$ 23,196
2.992% Notes Due 2025 (Issued March 2020) [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,500
Interest rate	2.992%
Debt Instrument Issuance Date	Mar. 19, 2020
3.294% Notes Due 2027 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,000
Interest rate	3.294%
Debt Instrument Issuance Date	Mar. 19, 2020
3.482% Notes Due 2030 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,000
Interest rate	3.482%
Debt Instrument Issuance Date	Mar. 19, 2020
4.227% Notes Due 2040 (Issued March 2020) [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,250
Interest rate	4.227%
Debt Instrument Issuance Date	Mar. 19, 2020
4.327% Notes Due 2050 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,750
Interest rate	4.327%
Debt Instrument Issuance Date	Mar. 19, 2020
1.571% Notes Due 2023 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,750
Interest rate	1.571%
Debt Instrument Issuance Date	Apr. 15, 2020
2.992% Notes Due 2025 (Issued April 2020) [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,314
Interest rate	2.992%
Debt Instrument Issuance Date	Apr. 15, 2020
2.610% Notes Due 2030 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,000
Interest rate	2.61%
Debt Instrument Issuance Date	Apr. 15, 2020
4.227% Notes Due 2040 (Issued April 2020) [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 842
Interest rate	4.227%
Debt Instrument Issuance Date	Apr. 15, 2020
3.452% Notes Due 2051 [Member] \| Other U.S. Dollar Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,750
Interest rate	3.452%
Debt Instrument Issuance Date	Apr. 15, 2020
2.992% Notes Due 2025 and 4.227% Notes Due 2040 [Member]
Debt Instrument [Line Items]
Debt instrument, unamortized premium	$ 156
0.142% Notes Due 2024 [Member] \| Other Foreign Currency Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,680
Interest rate	0.142%
Debt Instrument Issuance Date	Jun. 26, 2020
0.524% Notes Due 2028 [Member] \| Other Foreign Currency Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,120
Interest rate	0.524%
Debt Instrument Issuance Date	Jun. 26, 2020
0.835% Notes Due 2032 [Member] \| Other Foreign Currency Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,120
Interest rate	0.835%
Debt Instrument Issuance Date	Jun. 26, 2020
1.408% Notes Due 2039 [Member] \| Other Foreign Currency Obligations [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,120
Interest rate	1.408%
Debt Instrument Issuance Date	Jun. 26, 2020

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the debt instrument was issued, in CCYY-MM-DD format.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt premium.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant