CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2018	[1]	Jun. 30, 2017	Jun. 30, 2018	[1]	Jun. 30, 2017
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) [Abstract]
Net income		$ 51		$ 284	$ 259		$ 635
Change in value of pension and other postretirement liabilities:
Amortization of prior service cost and net loss included in net periodic pension cost	[2]			1			1
Comprehensive income		$ 51		$ 285	$ 259		$ 636

[1] In 2018, deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.

[2] Net of less than $1 million in taxes for the three and six months ended June 30, 2018 and 2017.