Oil and Gas Assets (Tables)

12 Months Ended

Dec. 31, 2014

Oil and Gas Property [Abstract]

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

	Costs Incurred In
	2014		2013		2012		2011 and Prior		Total
	(In millions)
Acquisition costs	$	185	$	159	$	41	$	84	$	469
Exploration costs	111		—		—		3		114
Fee mineral interests	—		1		—		23		24
Capitalized interest	53		17		—		—		70
Total oil and gas properties not subject to amortization	$	349	$	177	$	41	$	110	$	677

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:

	2014			2013
	(In millions)
Oil and gas properties:
Subject to amortization	$	15,707		$	15,107
Not subject to amortization	677			1,300
Gross oil and gas properties	16,384			16,407
Accumulated depreciation, depletion and amortization	(8,152		)	(8,306		)
Net oil and gas properties	$	8,232		$	8,101
Other property and equipment:
Furniture, fixtures and equipment	$	144		$	139
Gathering systems and equipment	114			104
Accumulated depreciation and amortization	(76		)	(69		)
Net other property and equipment	$	182		$	174