Variable Interest Entities - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Noncontrolling interests	$ 261		$ 261		$ 259
Net income attributable to noncontrolling interests	0	$ 18	0	$ 37
VIE, Cash and cash equivalents	4	2,051	4	2,051	825	$ 4,108
VIE. proved natural gas and oil properties	64,547		64,547		63,843
VIE. accumulated depreciation, depletion and amortization	(61,757)		(61,757)		(59,365)
Variable Interest Entities, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
VIE, Cash and cash equivalents	1		1		1
VIE. proved natural gas and oil properties	488		488		488
VIE. accumulated depreciation, depletion and amortization	(456)		(456)		$ (428)
Noncontrolling Interest, Chesapeake Granite Wash Trust [Member]
Variable Interest Entity [Line Items]
Net income attributable to noncontrolling interests	$ 0	$ 1	$ 0	$ 1