Fair Value Measurements - Fair Value Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Fair Value
Financial assets
Other noncurrent assets	$ 9	$ 10
Total financial assets	9	10
Financial liabilities
Other current liabilities	132	140
Long-term debt, including current portion	5,126	5,806
Deferred credits and other liabilities	45	73
Total financial liabilities	5,303	6,019
Carrying Amount
Financial assets
Other noncurrent assets	27	28
Total financial assets	27	28
Financial liabilities
Other current liabilities	198	204
Long-term debt, including current portion	5,297	5,948
Deferred credits and other liabilities	45	73
Total financial liabilities	$ 5,540	$ 6,225

This element represents the portion of the balance sheet assertion valued at fair value by the entity 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. This item represents financial assets reported as Other noncurrent assets on the Balance Sheet. Financial assets here include the noncurrent portion of receivables from United States Steel, restricted cash, long-term receivables, environmental receivables, and cost method investments.

No definition available.

Name:	mro_OtherNoncurrentAssetsFairValueDisclosure
Namespace Prefix:	mro_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant