Derivatives and Risk Management Activities (Details 6) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivative Asset Positions
Gross Position - Asset	$ 98	$ 191
Netting Adjustment	(110)	(148)
Cash collateral paid	164	41
Net Position - Asset	152	84
Derivative Liability Positions
Gross Position - Liability	(115)	(189)
Netting Adjustment	110	148
Net Position - Liability	(5)	(41)
Other current assets
Derivative Asset Positions
Net Position - Asset	133	76
Other long-term assets
Derivative Asset Positions
Net Position - Asset	19	8
Other current liabilities
Derivative Liability Positions
Net Position - Liability	(4)	(3)
Other long term liabilities
Derivative Liability Positions
Net Position - Liability	$ (1)	$ (38)