CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (747)	$ (2,160)	$ (2,356)	$ (5,288)
Adjustments for derivative instruments
Reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	2	2	7	7
Income taxes on reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	(1)	(1)	(3)	(3)
Total adjustments for derivative instruments, net of taxes	1	1	4	4
Adjustments for pension and other postretirement plans
Net gain (loss) incurred during period	(157)	0	(347)	0
Income taxes on net gain (loss) incurred during period	58	0	128	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	114	13	156	39
Income taxes on amortization of net actuarial (gain) loss to general and administrative expense	(43)	(5)	(59)	(14)
Amortization of net prior service (credit) cost to general and administrative expense	(6)	1	(27)	2
Income taxes on amortization of net prior service (credit) cost to general and administrative expense	2	(1)	10	(1)
Total adjustments for pension and other postretirement plans, net of taxes	(32)	8	(139)	26
Total	(31)	9	(135)	30
Comprehensive Income (Loss)	(778)	(2,151)	(2,491)	(5,258)
Comprehensive income (loss) attributable to noncontrolling interests	83	75	200	154
Comprehensive Income (Loss) Attributable to Common Stockholders	$ (861)	$ (2,226)	$ (2,691)	$ (5,412)