Consolidated Statements of Comprehensive Income - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Comprehensive Income
Net income (loss) attributable to common stock		$ 1,311	$ (574)	$ (7,829)
Other comprehensive income (loss) items:
Foreign currency translation (losses) gains		3		(2)
Unrealized gains (losses) on derivatives	[1]	13	(14)	3
Pension and postretirement gains (losses)	[2]	(7)	47	48
Reclassification of realized losses (gains) on derivatives	[3]	(1)	8	1
Other comprehensive income net of tax		8	41	50
Comprehensive income (loss)		$ 1,319	$ (533)	$ (7,779)

[1] Net of tax of $(7), $8 and $(2) in 2017, 2016 and 2015, respectively. The 2015 amount includes a lower of cost or market inventory adjustment for hedged natural gas of $(2).

[2] Net of tax of $4, $(26) and $(27) in 2017, 2016 and 2015, respectively. See Note 13 for additional information.

[3] Net of tax of zero, $(4) and $(1) in 2017, 2016 and 2015, respectively.