CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Defined benefit pension and other postretirement plan adjustments, tax	$ 0.0	$ (1.7)	$ 0.2	$ (1.1)
Net gain (loss) on derivatives, tax	$ 0.8	$ (1.5)	$ 0.0	$ (0.2)