Exploration Expense (Tables)

6 Months Ended

Jun. 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 June 30,				Six Months Ended June 30,
	2020		2019		2020		2019
	($ in millions)
Impairments of unproved properties	$	127	$	7	$	399	$	25
Dry hole expense	—		—		7		—
Geological and geophysical expense and other	3		8		6		14
Exploration expense	$	130	$	15	$	412	$	39