CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Natural gas and oil properties, using the full cost method, costs excluded from amortization	$ 1,518	$ 1,755
Common stock, par value (in dollars per shares)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,250,000,000	1,250,000,000
Common stock, shares issued (in shares)	585,637,420	585,407,107
Treasury stock, shares (in shares)	44,353,224	39,092,537

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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 10
-Section S99
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Face amount or stated value per share of common stock.

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Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
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