CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension and other postretirement plans adjustments:
Tax expense on net unamortized loss incurred	$ 0.0	$ 0.0	$ 0.2	$ 0.2
Tax expense on prior service cost incurred	$ 0.1	$ 0.5	$ 0.5	$ 1.5