Exploration Expense (Tables)

12 Months Ended

Dec. 31, 2020

Extractive Industries [Abstract]

Schedule of exploration expense

A summary of our exploration expense for the years ended December 31, 2020, 2019 and 2018 is as follows:

	Years Ended December 31,
	2020		2019		2018
	($ in millions)
Impairments of unproved properties	$	411	$	32	$	59
Dry hole expense	7		25		37
Geological and geophysical expense and other	9		27		66
Exploration expense	$	427	$	84	$	162