CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (611)	$ 108	$ (1,609)	$ (3,128)
Adjustments for derivative instruments
Reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	2	3	5	5
Income taxes on reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	(1)	(1)	(2)	(2)
Total adjustments for derivative instruments, net of taxes	1	2	3	3
Adjustments for pension and other postretirement plans
Net gain (loss) incurred during period	(24)	0	(190)	0
Income taxes on net gain (loss) incurred during period	9	0	70	0
Prior service credit (cost) incurred during period	0	0	(1)	0
Income taxes on prior service credit (cost) incurred during period	0	0	1	0
Amortization of net actuarial (gain) loss to general and administrative expense	34	13	42	26
Income taxes on amortization of net actuarial (gain) loss to general and administrative expense	(13)	(5)	(16)	(9)
Amortization of net prior service (credit) cost to general and administrative expense	(6)	1	(21)	1
Income taxes on amortization of net prior service (credit) cost to general and administrative expense	3	0	8	0
Total adjustments for pension and other postretirement plans, net of taxes	3	9	(107)	18
Total	4	11	(104)	21
Comprehensive Income (Loss)	(607)	119	(1,713)	(3,107)
Comprehensive income (loss) attributable to noncontrolling interests	81	47	117	79
Comprehensive Income (Loss) Attributable to Common Stockholders	$ (688)	$ 72	$ (1,830)	$ (3,186)