Derivative and Hedging Activities Natural Gas and Oil Sales Table (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Natural gas, oil and NGL sales	$ 1,839	$ 1,464	$ 5,303	$ 3,798
Gains (losses) on natural gas, oil and NGL derivatives	(253)	(27)	141	824
Total natural gas, oil and NGL sales	$ 1,586	$ 1,437	$ 5,444	$ 4,622