Fair Value Measurements and Disclosures (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010
Financial Assets Measured at Fair Value on a Recurring Basis [Abstract]
Mutual Fund Investments	$ 99		$ 112
Commodity Derivative Instruments	47		62
Financial Liabilities Measured at Fair Value on a Recurring Basis [Abstract]
Commodity Derivative Instruments	(83)		(75)
Interest Rate Derivative Instrument			(63)
Portion of Deferred Compensation Liability Measured at Fair Value	(162)		(178)
Quoted Prices in Active Markets (Level 1) [Member]
Financial Assets Measured at Fair Value on a Recurring Basis [Abstract]
Mutual Fund Investments	99	[1]	112	[1]
Commodity Derivative Instruments	0	[1]	0	[1]
Financial Liabilities Measured at Fair Value on a Recurring Basis [Abstract]
Commodity Derivative Instruments	0	[1]	0	[1]
Interest Rate Derivative Instrument			0	[1]
Portion of Deferred Compensation Liability Measured at Fair Value	(162)	[1]	(178)	[1]
Significant Other Observable Inputs (Level 2) [Member]
Financial Assets Measured at Fair Value on a Recurring Basis [Abstract]
Mutual Fund Investments	0	[1]	0	[1]
Commodity Derivative Instruments	99	[1]	106	[1]
Financial Liabilities Measured at Fair Value on a Recurring Basis [Abstract]
Commodity Derivative Instruments	(135)	[1]	(119)	[1]
Interest Rate Derivative Instrument			(63)	[1]
Portion of Deferred Compensation Liability Measured at Fair Value	0	[1]	0	[1]
Significant Unobservable Inputs (Level 3) [Member]
Financial Assets Measured at Fair Value on a Recurring Basis [Abstract]
Mutual Fund Investments	0	[1]	0	[1]
Commodity Derivative Instruments	0	[1]	0	[1]
Financial Liabilities Measured at Fair Value on a Recurring Basis [Abstract]
Commodity Derivative Instruments	0	[1]	0	[1]
Interest Rate Derivative Instrument			0	[1]
Portion of Deferred Compensation Liability Measured at Fair Value	0	[1]	0	[1]
Fair Value Inputs Adjustment [Member]
Financial Assets Measured at Fair Value on a Recurring Basis [Abstract]
Mutual Fund Investments	0	[2]	0	[2]
Commodity Derivative Instruments	(52)	[2]	(44)	[2]
Financial Liabilities Measured at Fair Value on a Recurring Basis [Abstract]
Commodity Derivative Instruments	52	[2]	44	[2]
Interest Rate Derivative Instrument			0	[2]
Portion of Deferred Compensation Liability Measured at Fair Value	$ 0	[2]	$ 0	[2]

[1] See Note 1. Summary of Significant Accounting Policies - Fair Value Measurements for a description of the fair value hierarchy.

[2] Amount represents the impact of master netting agreements that allow us to settle asset and liability positions with the same counterparty.