Statement of Consolidated Changes in Equity - USD ($) $ in Millions	Total	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss) [Member]	Parent [Member]	Noncontrolling Interest [Member]	Series D Preferred Stock [Member]
BALANCE at Dec. 31, 2012	$ 31,331	$ 245	$ 9,859	$ 20,161	$ (30)	$ (131)	$ 31,331		$ 1,227
Net income (loss)	2,288			2,232			2,232	$ 56
Postretirement, net of tax of $9	9					9	9
Commodity hedges, net of tax	7					7	7
Preferred	(44)			(44)			(44)
Common dividends	(317)			(317)			(317)
Common stock activity, net	(21)	1	(22)				(21)
Treasury stock activity, net	(997)				(997)		(997)
Sale of noncontrolling interest	2,948		1,007				1,007	1,941
Conversion of Series D preferred stock		9	1,218						$ (1,227)
Compensation expense	189		189				189
BALANCE at Dec. 31, 2013	35,393	255	12,251	22,032	(1,027)	(115)	33,396	1,997
Net income (loss)	(5,060)			(5,403)			(5,403)	343
Distributions to noncontrolling interest	(140)							(140)
Commodity hedges, net of tax	(1)					(1)	(1)
Common dividends	(380)			(380)			(380)
Common stock activity, net	(10)	1	(11)				(10)
Treasury stock activity, net	(1,864)		(1)		(1,863)		(1,864)
Compensation expense	202		202				202
Other	(3)		(3)				(3)
BALANCE at Dec. 31, 2014	28,137	256	12,438	16,249	(2,890)	(116)	25,937	2,200
Net income (loss)	(23,528)			(23,119)			(23,119)	(409)
Distributions to noncontrolling interest	(129)							(129)
Common dividends	(378)		(95)	(283)			(378)
Common stock activity, net	(14)	1	(15)				(14)
Treasury stock activity, net			(1)		1
Compensation expense	140		140				140
BALANCE at Dec. 31, 2015	$ 4,228	$ 257	$ 12,467	$ (7,153)	$ (2,889)	$ (116)	$ 2,566	$ 1,662