CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
Net Income (Loss)	$ (1,563)	$ 941	$ 2,445
Adjustments for derivative instruments
Reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	9	11	12
Income taxes on reclassification of previously deferred derivative losses to (gains) losses on derivatives, net	(3)	(4)	(4)
Total adjustments for derivative instruments, net of taxes	6	7	8
Adjustments for pension and other postretirement plans
Net gain (loss) incurred during period	(405)	416	(155)
Income taxes on net gain (loss) incurred during period	149	(152)	56
Amortization of net actuarial (gain) loss to general and administrative expense	27	132	93
Income taxes on amortization of net actuarial (gain) loss to general and administrative expense	(9)	(49)	(32)
Amortization of net prior service (credit) cost to general and administrative expense	0	1	2
Total adjustments for pension and other postretirement plans, net of taxes	(238)	348	(36)
Total	(232)	355	(28)
Comprehensive Income (Loss)	(1,795)	1,296	2,417
Comprehensive income attributable to noncontrolling interests	187	140	54
Comprehensive Income (Loss) Attributable to Common Stockholders	$ (1,982)	$ 1,156	$ 2,363