Consolidated Statement Of Equity (USD $) In Millions, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Noncontrolling Interests [Member]
Beginning Balance at Dec. 31, 2013	$ 6,615	$ 1	$ 5,080	$ (144)	$ 1,665	$ 13
Beginning Balance, shares at Dec. 31, 2013		143,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared ($0.08 per share)	(12)				(12)
Exercise of long-term incentive plan stock options and employee stock purchases, shares		0
Exercise of long-term incentive plan stock options and employee stock purchases	13		6	7
Treasury stock purchases, shares		0
Treasury stock purchases	(33)			(33)
Sendero divestiture	(4)		0			(4)
Tax benefit related to stock-based compensation	14		14
Pioneer Southwest merger transaction costs	(1)		(1)
Compensation costs:
Compensation costs included in net income	63		63			0
Cash distributions to noncontrolling interests	(1)					(1)
Net income	499				499	0
Ending Balance at Sep. 30, 2014	$ 7,153	$ 1	$ 5,162	$ (170)	$ 2,152	$ 8
Ending Balance, shares at Sep. 30, 2014		143,000,000