Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net income	$ 18.8	$ 80.3	$ 103.4	$ 321.1
Other comprehensive income
Foreign currency translation loss	0.0	(0.3)	(0.1)	(0.4)
Defined benefit pension and postretirement plans
Net gain arising from remeasurement during the period, net of tax of $0.6	0.0	0.0	0.0	1.1
Amortization of prior service benefits, net of tax of ($1.2), ($1.3), ($3.9), ($4.1)	(2.4)	(2.6)	(7.1)	(7.4)
Amortization of net actuarial loss, net of tax of $2.1, $2.3, $6.4, $8.5	3.8	4.3	11.6	15.3
Reclassification adjustment for curtailment loss included in net income, net of tax of $0.1	0.0	0.0	0.0	0.2
Other comprehensive income	1.4	1.4	4.4	8.8
Total comprehensive income	$ 20.2	$ 81.7	$ 107.8	$ 329.9