Derivative Instruments and Hedging Activities (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair Values of Derivative Instruments Recorded in the Consolidated Balance Sheet
Total Assets	$ 307	$ 332
Total Liabilities	205	154
Deferred Charges and Other [Member]
Fair Values of Derivative Instruments Recorded in the Consolidated Balance Sheet
Other Assets: Deferred charges and other	23	28
Derivative Instruments [Member]
Fair Values of Derivative Instruments Recorded in the Consolidated Balance Sheet
Current Assets: Derivative instruments	284	304
Current Liabilities: Derivative instruments	150	113
Other Liabilities [Member]
Fair Values of Derivative Instruments Recorded in the Consolidated Balance Sheet
Noncurrent Liabilities: Other	$ 55	$ 41