Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	$ 82	$ 86
Total Liabilities at Fair Value	86	149
Accounts and notes receivable, net [Member] | Commodity [Member]
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	65	57
Long term receivables, net [Member] | Commodity [Member]
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Assets at Fair Value	17	29
Accounts payable [Member] | Commodity [Member]
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Liabilities at Fair Value	52	112
Deferred credits and other noncurrent obligations [Member] | Commodity [Member]
Consolidated Balance Sheet: Fair Value of Derivatives not Designated as Hedging Instruments
Total Liabilities at Fair Value	$ 34	$ 37