Asset Acquisitions, Dispositions and Other (Details) (USD $)	1 Months Ended		6 Months Ended
	Apr. 30, 2014	Feb. 28, 2014	Jun. 30, 2014
Acquisitions, dispositions and other transactions
Pre-tax gain on sale of property			$ 535,000,000
Hugoton Field operations
Acquisitions, dispositions and other transactions
Agreed value of proceeds from sale of assets		1,400,000,000
Pre-tax proceeds from sale of assets	1,300,000,000
Pre-tax gain on sale of property			535,000,000
Gain on sale of property, after tax			$ 341,000,000