Acquisitions (Unaudited) Redeemable Noncontrolling Interest (Details) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended				9 Months Ended	12 Months Ended			1 Months Ended		2 Months Ended	9 Months Ended		1 Months Ended		2 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Jun. 03, 2013	Dec. 31, 2012	Sep. 30, 2013 Plains Offshore Operations Inc. [Member]	Dec. 31, 2011 Plains Offshore Operations Inc. [Member]	May 31, 2013 Plains Offshore Operations Inc. [Member]	Dec. 31, 2011 Minimum [Member] Plains Offshore Operations Inc. [Member] ft	Jul. 31, 2013 8% Convertible Perpetual Preferred Stock [Member]	Jun. 30, 2013 8% Convertible Perpetual Preferred Stock [Member]	Jul. 31, 2013 8% Convertible Perpetual Preferred Stock [Member]	Sep. 30, 2013 8% Convertible Perpetual Preferred Stock [Member]	Jul. 09, 2013 8% Convertible Perpetual Preferred Stock [Member]	Jul. 31, 2013 5.75% Convertible Perpetual Preferred Stock, Series 1 [Member]	Jun. 30, 2013 5.75% Convertible Perpetual Preferred Stock, Series 1 [Member]	Jul. 31, 2013 5.75% Convertible Perpetual Preferred Stock, Series 1 [Member]	Sep. 30, 2013 5.75% Convertible Perpetual Preferred Stock, Series 1 [Member]	Jul. 09, 2013 5.75% Convertible Perpetual Preferred Stock, Series 1 [Member]
Redeemable Noncontrolling Interest [Line Items]
Preferred Stock Of Subsidiary						450,000
Preferred Stock, Dividend Rate, Percentage												8.00%					5.75%
Preferred Stock Conversion, Converted Instrument, Expiration or Due Date										Jul. 09, 2013					Jul. 09, 2013
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					8.00%
Preferred Stock Dividend Rate Percentage Deferred					2.00%
Dividends Payable					20
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	720			0	719		713			30			1		229			0
Conversion of Stock, Amount Converted									0	29				29	200
Royalty Trust Units Issued, Conversion of Debt or Equity Instrument									0	2,000,000	2,000,000			2,000,000	13,700,000	15,700,000
Payments for Repurchase of Preferred Stock and Preference Stock	227	0
Royalty Trust Units, Fair Value Disclosure			$ 31