Consolidated Balance Sheet (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Property and equipment, at cost, based on the full cost method of accounting for oil and gas properties	$ 1,300	$ 1,485
Stockholders' equity:
Preferred stock ($0.01 par value)	$ 0.01	$ 0.01
Preferred stock (5,000,000 shares authorized)	5,000,000	5,000,000
Preferred stock (no shares issued)	0	0
Common stock ($0.01 par value)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	136,682,631	136,530,907
Treasury Stock, shares	460,914	1,216,591
Commitments and Contingencies	$ 0	$ 0