Oil and Gas Properties [Tables]

3 Months Ended

Mar. 31, 2018

Oil and Gas Property [Abstract]

Oil and Gas Properties [Table Text Block]

Oil and gas properties consisted of the following:

	March 31,   2018			December 31,   2017
	(In millions)
Proved	$	23,614		$	23,272
Unproved	1,245			1,200
Gross oil and gas properties	24,859			24,472
Accumulated depreciation, depletion and amortization	(10,163		)	(10,032		)
Accumulated impairment	(10,509		)	(10,509		)
Net oil and gas properties	$	4,187		$	3,931

Costs withheld from amortization [Table Text Block]

Costs withheld from amortization as of March 31, 2018 consisted of the following:

	Costs Incurred In
	2018		2017		2016		2015 & Prior		Total
	(In millions)
Acquisition costs	$	28	$	108	$	483	$	319	$	938
Exploration costs	—		—		—		—		—
Capitalized internal cost	4		38		49		47		138
Capitalized interest	15		61		51		42		169
Total costs withheld from amortization	$	47	$	207	$	583	$	408	$	1,245