Consolidated Statements of Comprehensive Income Parenthetical - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net (loss) gain arising from remeasurement during the period, tax	$ (3.4)	$ (25.0)	$ 30.7
Net prior service credit, tax	0.0	0.0	6.1
Amortization of prior service benefits included in net income (loss), tax	(5.5)	(5.4)	(5.2)
Amortization of net actuarial loss included in net income (loss), tax	10.8	8.0	10.1
Reclassification adjustment for curtailment loss (gain) included in net income (loss), tax	$ 0.1	$ 0.0	$ (0.2)