Exploration Expense (Tables)

9 Months Ended

Sep. 30, 2020

Extractive Industries [Abstract]

Schedule of exploration expense

A summary of our exploration expense for the Current Quarter, the Prior Quarter, the Current Period and the Prior Period is as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
	($ in millions)
Impairments of unproved properties	$	3	$	1	$	402	$	26
Dry hole expense	—		8		7		8
Geological and geophysical expense and other	2		8		8		22
Exploration expense	$	5	$	17	$	417	$	56