STATEMENTS OF CONSOLIDATED COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 745	$ 245	$ (912)
Other comprehensive income (loss), net of tax:
Adjustment to postretirement and other postemployment plans (net of tax of $4, $4 and $6)	4	(6)	8
Net deferred loss from cash flow hedges (net of tax of $1, $-0-, and $-0-, respectively)	(1)	0	0
Other comprehensive income (loss)	3	(6)	8
Comprehensive income (loss)	$ 748	$ 239	$ (904)