Derivative and Hedging Activities - Oil, Natural Gas and NGL Revenues Table (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Oil, natural gas and NGL revenues	$ 1,079	$ 884	$ 2,226	$ 1,696
Gains (losses) on undesignated oil, natural gas and NGL derivatives	207	(438)	539	(246)
Losses on terminated cash flow hedges	(7)	(6)	(17)	(17)
Total oil, natural gas and NGL revenues	$ 1,279	$ 440	$ 2,748	$ 1,433