Long-Term Debt (Summarized Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Long-term Debt [Line Items]
Debt issuance costs	$ (78)	$ (88)
Long-term debt	36,755	37,483
Exxon Mobil Corporation [Member]
Long-term Debt [Line Items]
Debt instrument, unamortized premium	76	97
XTO Energy Inc. [Member]
Long-term Debt [Line Items]
Debt instrument, unamortized premium	66	71
Pioneer Natural Resources
Long-term Debt [Line Items]
Debt instrument, unamortized discount, net	348
Parsley Energy LLC
Long-term Debt [Line Items]
Debt instrument, unamortized discount	7
2.709% notes due 2025 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 0	1,750
Interest rate	2.709%
2.992% notes due 2025 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 0	2,767
Interest rate	2.992%
3.043% notes due 2026 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,500	2,500
Interest rate	3.043%
2.275% notes due 2026 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,000	1,000
Interest rate	2.275%
3.294% notes due 2027 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,000	1,000
Interest rate	3.294%
2.440% notes due 2029 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,250	1,250
Interest rate	2.44%
3.482% notes due 2030 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,992	2,000
Interest rate	3.482%
2.610% notes due 2030 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,000	2,000
Interest rate	2.61%
2.995% notes due 2039 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 750	750
Interest rate	2.995%
4.227% notes due 2040 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,076	2,080
Interest rate	4.227%
3.567% notes due 2045 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,000	1,000
Interest rate	3.567%
4.114% notes due 2046 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,500	2,500
Interest rate	4.114%
3.095% notes due 2049 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,500	1,500
Interest rate	3.095%
4.327% notes due 2050 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,750	2,750
Interest rate	4.327%
3.452% notes due 2051 | Exxon Mobil Corporation [Member] | Other U.S. Dollar Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 2,750	2,750
Interest rate	3.452%
0.524% notes due 2028 | Exxon Mobil Corporation - Euro-denominated | Other Foreign Currency Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,039	1,105
Interest rate	0.524%
0.835% notes due 2032 | Exxon Mobil Corporation - Euro-denominated | Other Foreign Currency Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,039	1,105
Interest rate	0.835%
1.408% notes due 2039 | Exxon Mobil Corporation - Euro-denominated | Other Foreign Currency Obligations [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,039	1,105
Interest rate	1.408%
6.100% senior notes due 2036 | XTO Energy Inc. [Member] | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 187	189
Interest rate	6.10%
6.750% senior notes due 2037 | XTO Energy Inc. [Member] | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 284	286
Interest rate	6.75%
6.375% senior notes due 2038 | XTO Energy Inc. [Member] | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 221	223
Interest rate	6.375%
1.125% senior notes due 2026 | Pioneer Natural Resources | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 718	0
Interest rate	1.125%
5.100% senior notes due 2026 | Pioneer Natural Resources | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 1,097	0
Interest rate	5.10%
7.200% senior notes due 2028 | Pioneer Natural Resources | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 250	0
Interest rate	7.20%
1.900% senior notes due 2030 | Pioneer Natural Resources | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 931	0
Interest rate	1.90%
2.150% senior notes due 2031 | Pioneer Natural Resources | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 846	0
Interest rate	2.15%
4.125% senior notes due 2028 | Parsley Energy LLC | Senior Notes [Member]
Long-term Debt [Line Items]
Senior notes, noncurrent	$ 131	0
Interest rate	4.125%
Industrial revenue bonds due 2025-2051 | Combined Exxon Mobil And Affiliates [Member]
Long-term Debt [Line Items]
Other long-term debt	$ 2,032	2,123
Average effective interest rate	3.149%
Finance leases & other obligations | Combined Exxon Mobil And Affiliates [Member]
Long-term Debt [Line Items]
Average effective interest rate	4.577%
Finance lease liability - noncurrent included in Long-term debt	$ 3,951	$ 3,838