Asset Sales, Impairments and Exploration Expenses (Tables)

12 Months Ended

Dec. 31, 2019

Extractive Industries [Abstract]

Summary of exploration expenses

The following table presents a summary of exploration expenses.

	Years Ended December 31,
	2019		2018		2017
	(Millions)
Unproved leasehold property impairments, amortization and expiration	$	89	$	69	$	84
Geologic and geophysical costs	6		$	6	3
Total exploration expenses	$	95	$	75	$	87