Statements of Consolidated Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net income (loss)	$ 91.7	$ (236.6)	$ 71.8
Other comprehensive (loss) income, net of tax – Note 15:
Defined benefit pension plan and VEBAs	(5.8)	65.1	(75.6)
Available for sale securities	0.9	(0.3)	(0.2)
Foreign currency translation	(0.1)	(0.2)	0.4
Other comprehensive (loss) income, net of tax	(5.0)	64.4	(75.4)
Comprehensive income (loss)	86.7	(172.2)	(3.6)
Foreign Exchange Contract
Other comprehensive (loss) income, net of tax – Note 15:
Foreign currency cash flow hedge and Alloy hedges	0.1	(0.2)	0.0
Alloy Metal Hedge
Other comprehensive (loss) income, net of tax – Note 15:
Foreign currency cash flow hedge and Alloy hedges	$ (0.1)	$ 0.0	$ 0.0