Oil and Gas Assets (Tables)

12 Months Ended

Dec. 31, 2013

Oil and Gas Property [Abstract]

Costs incurred by year for oil and gas properties not subject to amortization

	Costs Incurred In
	2013		2012		2011		2010 and Prior		Total
	(In millions)
Acquisition costs	$	206	$	114	$	188	$	300	$	808
Exploration costs	175		21		9		35		240
Development costs	13		31		25		—		69
Fee mineral interests	1		—		—		23		24
Capitalized interest	53		68		38		—		159
Total oil and gas properties not subject to amortization	$	448	$	234	$	260	$	358	$	1,300

Capitalized Costs Relating to Oil and Gas Producing Activities and Other PPE [Table Text Block]

Property and equipment consisted of the following at December 31:

	2013			2012
	(In millions)
Oil and gas properties:
Subject to amortization	$	15,107		$	12,647
Not subject to amortization	1,300			1,485
Gross oil and gas properties	16,407			14,132
Accumulated depreciation, depletion and amortization	(8,306		)	(7,378		)
Net oil and gas properties	8,101			6,754
Other property and equipment:
Furniture, fixtures and equipment	139			141
Gathering systems and equipment	104			73
Accumulated depreciation and amortization	(69		)	(66		)
Net other property and equipment	174			148
Total property and equipment, net	$	8,275		$	6,902