Supplemental Information on Oil And Gas Producing Activities (Unaudited) - Costs Incurred for Oil and Gas Producing Activities (Detail) - ARS ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Argentina [member]
Disclosure of information about consolidated structured entities [Line Items]
Acquisition of unproved properties	$ 0	$ 0	$ 0
Acquisition of proved properties	154	2,093
Exploration costs	3,302	2,922	4,029
Development costs	39,039	49,302	44,753
Total costs incurred	42,495	54,317	48,782
Other foreign [Member]
Disclosure of information about consolidated structured entities [Line Items]
Acquisition of unproved properties	0	0	0
Exploration costs	149	517	440
Development costs		25	84
Total costs incurred	149	542	524
Worldwide [Member]
Disclosure of information about consolidated structured entities [Line Items]
Acquisition of unproved properties	0	0	0
Acquisition of proved properties	154	2,093
Exploration costs	3,451	3,439	4,469
Development costs	39,039	49,327	44,837
Total costs incurred	$ 42,644	$ 54,859	$ 49,306

- Definition

The capitalized costs incurred during the period (excluded from amortization) in identifying areas that may warrant examination and in examining specific areas that are considered to have prospects of containing oil and gas reserves, including costs of drilling exploratory wells and exploratory-type stratigraphic test wells. Exploration costs may be incurred both before acquiring the related property (sometimes referred to in part as prospecting costs) and after acquiring the property. Principal types of exploration costs, which include depreciation and applicable operating costs of support equipment and facilities and other costs of exploration activities, are: costs of topographical, geographical and geophysical studies, rights of access to properties to conduct those studies, and salaries and other expenses of geologists, geophysical crews, and others conducting those studies. Collectively, these are sometimes referred to as geological and geophysical or "G&G" costs. Exploration costs also include costs of carrying and retaining undeveloped properties, such as delay rentals, ad valorem taxes on properties, legal costs for title defense, the maintenance of land and lease records, dry hole contributions and bottom hole contributions, costs of drilling and equipping exploratory wells and costs of drilling exploratory-type stratigraphic test wells.

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