CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (2,160)	$ 1,147	$ (5,288)	$ (1,213)
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
Amortization of net actuarial (gain) loss to general and administrative expense	13	7	39	21
Income taxes on amortization of net actuarial (gain) loss to general and administrative expense	(5)	(2)	(14)	(7)
Amortization of net prior service (credit) cost to general and administrative expense	1	0	2	0
Income taxes on amortization of net prior service (credit) cost to general and administrative expense	(1)	0	(1)	0
Total adjustments for pension and other postretirement plans, net of taxes	8	5	26	14
Total	9	6	30	18
Comprehensive Income (Loss)	(2,151)	1,153	(5,258)	(1,195)
Comprehensive income attributable to noncontrolling interests	75	60	154	142
Comprehensive Income (Loss) Attributable to Common Stockholders	$ (2,226)	$ 1,093	$ (5,412)	$ (1,337)