CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	[1]	Sep. 30, 2019	Sep. 30, 2018	[1]
Statement of Comprehensive Income [Abstract]
Net income (loss)		$ 49	$ (29)		$ 781	$ 230
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	4		5	4
Comprehensive income (loss)		$ 50	$ (25)		$ 786	$ 234

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

[2] Primarily related to settlement of pension assets in 2019 and the curtailment of pension assets in 2018. Net of less than $1 million and $1 million in taxes for the three months ended September 30, 2019 and 2018, respectively, and $2 million and $1 million in taxes for the nine months ended September 30, 2019 and 2018, respectively.