STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 245	$ (912)	$ 323
Other comprehensive income (loss), net of tax:
Adjustment to postretirement and other postemployment plans (net of tax of $4, $6 and $1)	(6)	8	(4)
Other comprehensive income (loss)	(6)	8	(4)
Comprehensive income (loss)	$ 239	$ (904)	$ 319