Impairment (Tables)

12 Months Ended

Dec. 31, 2019

Impairments and Exploration Expenses [Abstract]

Fair Value Measurements, Nonrecurring [Table Text Block]

The following table summarizes impairment charges of proved properties from continuing operations. Additionally, it presents the values of assets, by major category, measured at fair value on a nonrecurring basis in periods subsequent to their initial recognition.

	2019				2018				2017
(In millions)	Fair Value		Impairment		Fair Value		Impairment		Fair Value		Impairment
Long-lived assets held for use	$	56	$	24	$	113	$	75	$	179	$	229