Derivatives (Details 1) In Millions, unless otherwise specified																																			3 Months Ended
	Mar. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2012 Prepaid expenses and other assets [Member] USD ($)	Dec. 31, 2011 Prepaid expenses and other assets [Member] USD ($)	Mar. 31, 2012 Other Assets [Member] USD ($)	Dec. 31, 2011 Other Assets [Member] USD ($)	Mar. 31, 2012 Other Liabilities [Member] USD ($)	Dec. 31, 2011 Other Liabilities [Member] USD ($)	Mar. 31, 2012 Other Noncurrent Liabilities [Member] USD ($)	Dec. 31, 2011 Other Noncurrent Liabilities [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] CAD	Mar. 31, 2012 Designated as Hedging Instrument [Member] JPY (¥)	Dec. 31, 2011 Designated as Hedging Instrument [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] CAD	Dec. 31, 2011 Designated as Hedging Instrument [Member] JPY (¥)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Prepaid expenses and other assets [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Prepaid expenses and other assets [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Other Assets [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Other Assets [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Other Liabilities [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Other Liabilities [Member] USD ($)	Mar. 31, 2012 Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] USD ($)	Dec. 31, 2011 Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] USD ($) Gallons	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] USD ($) Gallons	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Prepaid expenses and other assets [Member] USD ($)	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Prepaid expenses and other assets [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Other Assets [Member] USD ($)	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Other Assets [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Other Liabilities [Member] USD ($)	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Other Liabilities [Member] USD ($)	Mar. 31, 2012 Not Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] USD ($)	Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Other Noncurrent Liabilities [Member] USD ($)	Mar. 31, 2012 InterestRateCashFlowHedgesContract [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 InterestRateCashFlowHedgesContract [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 InterestRateFairValueHedgesContract [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 InterestRateFairValueHedgesContract [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Foreign Exchange Contract [Member] Designated as Hedging Instrument [Member]	Dec. 31, 2011 Foreign Exchange Contract [Member] Designated as Hedging Instrument [Member]	Mar. 31, 2012 Commodity Contract [Member] Not Designated as Hedging Instrument [Member]	Dec. 31, 2011 Commodity Contract [Member] Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Notional Amount of Interest Rate Cash Flow Hedge Derivatives											$ 952			$ 989
Derivative, Maturity Date																																			May 31, 2019	May 31, 2019	Aug. 31, 2022	Aug. 31, 2022	Nov. 30, 2014	Apr. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Interest Rate Cash Flow Hedge Asset at Fair Value																	0	0	0	0
Interest Rate Cash Flow Hedge Liability at Fair Value																					(27)	(27)	(51)	(57)
Interest Rate Cash Flow Hedge Derivative at Fair Value, Net											(78)			(84)
Notional Amount of Interest Rate Fair Value Hedge Derivatives											485			500
Interest Rate Fair Value Hedge Asset at Fair Value																	5	0	0	0
Interest Rate Fair Value Hedge Liability at Fair Value																					0	0	(18)	(7)
Interest Rate Fair Value Hedge Derivative at Fair Value, Net											(13)			(7)
Notional Amount of Foreign Currency Derivatives												322	110,802		313	126,993
Foreign Currency Cash Flow Hedge Asset at Fair Value																	18	7	23	5
Foreign Currency Cash Flow Hedge Liability at Fair Value																					6	58	1	43
Foreign Currency Cash Flow Hedge Derivative at Fair Value, Net	34	(89)									34			(89)
Nonmonetary Notional Amount of Price Risk Derivatives																									2,430,000,000	1,225,000,000
Price Risk Derivative Assets, at Fair Value																											426	570	0	0
Price Risk Derivative Liabilities, at Fair Value																															(221)	(500)	(15)	0
Price Risk Derivatives, at Fair Value, Net	190	70																							190	70
Derivative Asset, Fair Value, Gross Asset			449	577	23	5
Derivative Liability, Fair Value, Gross Liability							254	585	85	107
Derivative, Fair Value, Net	$ 133	$ (110)