Derivative Instruments And Hedging Activities (Fair Value Of Derivative Instruments By Balance Sheet Location) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Derivative Assets (current assets)	$ 22	$ 45
Derivative Liabilities (current liabilities)	(47)	(66)
Derivative Liabilities (non-current liabilities)	(9)	(21)
Derivatives Designated As Hedging Instruments [Member]
Derivative Assets (current assets)	30	40
Derivative Assets (non-current assets)		16
Total Derivative Assets	30	56
Derivative Liabilities (current liabilities)	(92)	(125)
Derivative Liabilities (non-current liabilities)	(24)	(68)
Total Derivative Liabilities	(116)	(193)
Net Derivative (Liability) Asset	(86)	(137)
Other Derivative Instruments [Member]
Derivative Assets (current assets)	20	43
Derivative Assets (non-current assets)	2	3
Total Derivative Assets	22	46
Derivative Liabilities (current liabilities)	(38)	(63)
Derivative Liabilities (non-current liabilities)	(10)	(10)
Total Derivative Liabilities	(48)	(73)
Net Derivative (Liability) Asset	(26)	(27)
Gross Derivative Instruments [Member]
Derivative Assets (current assets)	50	83
Derivative Assets (non-current assets)	2	19
Total Derivative Assets	52	102
Derivative Liabilities (current liabilities)	(130)	(188)
Derivative Liabilities (non-current liabilities)	(34)	(78)
Total Derivative Liabilities	(164)	(266)
Net Derivative (Liability) Asset	(112)	(164)
Effects Of Cash Collateral And Netting [Member]
Derivative Assets (current assets)	(28)	(38)
Derivative Assets (non-current assets)	(2)	(19)
Total Derivative Assets	(30)	(57)
Derivative Liabilities (current liabilities)	83	122
Derivative Liabilities (non-current liabilities)	25	57
Total Derivative Liabilities	108	179
Net Derivative (Liability) Asset	78	122
Net Derivative Instruments [Member]
Derivative Assets (current assets)	22	45
Total Derivative Assets	22	45
Derivative Liabilities (current liabilities)	(47)	(66)
Derivative Liabilities (non-current liabilities)	(9)	(21)
Total Derivative Liabilities	(56)	(87)
Net Derivative (Liability) Asset	$ (34)	$ (42)