Consolidated Balance Sheet (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
ASSETS
Property and equipment, at cost, based on the full cost method of accounting for oil and gas properties	$ 677	$ 1,300
Stockholders' equity:
Preferred stock ($0.01 par value)	$ 0.01	$ 0.01
Preferred stock (5,000,000 shares authorized)	5,000,000us-gaap_PreferredStockSharesAuthorized	5,000,000us-gaap_PreferredStockSharesAuthorized
Preferred stock (no shares issued)	0us-gaap_PreferredStockSharesIssued	0us-gaap_PreferredStockSharesIssued
Common stock ($0.01 par value)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000us-gaap_CommonStockSharesAuthorized	200,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	137,603,643us-gaap_CommonStockSharesIssued	136,682,631us-gaap_CommonStockSharesIssued
Treasury Stock, shares	275,069us-gaap_TreasuryStockShares	460,914us-gaap_TreasuryStockShares
Commitments and Contingencies	$ 0us-gaap_CommitmentsAndContingencies	$ 0us-gaap_CommitmentsAndContingencies

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The sum of the capitalized costs incurred, as of the balance sheet date, of unproved properties excluded from amortization including acquisition costs, exploration costs, development costs, and production costs.

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