Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Net income	$ 77.6	$ 191.6	$ 84.6	$ 240.8
Other comprehensive income
Foreign currency translation gain (loss)	0.0	0.2	(0.1)	(0.1)
Defined benefit pension and postretirement plans
Net gain arising from remeasurement during the period, net of tax of $0.6	0.0	1.1	0.0	1.1
Amortization of prior service benefits, net of tax of ($1.3), ($1.4), ($2.7), ($2.8)	(2.4)	(2.4)	(4.7)	(4.8)
Amortization of net actuarial loss, net of tax of $2.2, $3.8, $4.3, $6.2	3.9	6.9	7.8	11.0
Reclassification adjustment for curtailment loss included in net income, net of tax of $0.1	0.0	0.2	0.0	0.2
Other comprehensive income	1.5	6.0	3.0	7.4
Total comprehensive income	$ 79.1	$ 197.6	$ 87.6	$ 248.2