CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (PARENTHETICAL) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Change in derivative losses on cash flow hedges, taxes	$ 0.0	$ 2.7	$ 0.0
Amortization of net actuarial losses and prior service cost, taxes	0.8	10.9	1.2
Adjustments of net actuarial losses and prior service cost, taxes	$ 2.1	$ 7.1	$ 3.9