CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Income and Comprehensive Income [Line Items]
Net income (loss)	$ 125	$ (3)	$ (535)
Other comprehensive income (loss), net of tax:
Change in fair value of commodity hedges	0	0	(3)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	0	0	(6)
Actuarial gain (loss) relating to postretirement benefits, net of tax amounts of $0, $1, and ($15), respectively	2	(3)	25
Total other comprehensive income (loss)	2	(3)	28
Comprehensive income (loss)	$ 127	$ (6)	$ (507)