Derivative and Hedging Activities Derivative and Hedging Activities - Marketing, Gathering and Compression Sales (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Marketing, gathering and compression revenues	$ 1,284	$ 940
Gains (losses) on undesignated supply contract derivatives	0	20
Total marketing, gathering and compression revenues	$ 1,284	$ 960