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)	$ (749)	$ 431	$ (1,411)	$ 2,120
Postretirement and postemployment plans
Change in actuarial loss and other	(2)	3	160	(40)
Income tax benefit (provision) on postretirement and postemployment plans	(1)	(2)	(58)	13
Postretirement and postemployment plans, net of tax	(3)	1	102	(27)
Comprehensive income (loss)	$ (752)	$ 432	$ (1,309)	$ 2,093