Acquisitions (Unaudited) Redeemable Noncontrolling Interest (Details) (USD $) In Millions, except Share data, unless otherwise specified			6 Months Ended	12 Months Ended		6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Plains Offshore Operations Inc. [Member]	Dec. 31, 2011 Plains Offshore Operations Inc. [Member]	May 31, 2013 Plains Offshore Operations Inc. [Member]	Jun. 30, 2013 8% Convertible Perpetual Preferred Stock [Member]	Jul. 09, 2013 8% Convertible Perpetual Preferred Stock [Member]	Dec. 31, 2011 Minimum [Member] Plains Offshore Operations Inc. [Member] ft
Redeemable Noncontrolling Interest [Line Items]
Preferred Stock Of Subsidiary				450,000
Preferred Stock, Dividend Rate, Percentage						8.00%
Gross Proceeds from Issuance of Convertible Preferred Stock				$ 450
Nondetachable Warrants				9,100,000
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 20
Common Stock Held In Escrow				87,000,000
Depth of Oil and Gas Properties								500
Equity Interest Held By Outside Party, Percent				20.00%
Preferred Stock Quarterly Cash Dividend Annual Rate Percentage			6.00%
Preferred Stock Dividend Rate Percentage Deferred			2.00%
Dividends Payable			18
Participating Dividends Future Multiple			4
Percentage Of Common Shares Diluted Basis Related To Failed Exit Event Consideration				49.00%
Failed Exit Event Parents Purchase Amount Of Junior Preferred Stock				300
Liquidation Preference Multiple				1.25
Temporary Equity, Redemption Value	$ 782	$ 0	$ 752		$ 749	$ 30	$ 1