Condensed Consolidated Statements of Comprehensive Income (Unaudited) (Parenthetical) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Tax expense on change in unrecognized net actuarial losses related to pension benefit plans	$ 0.2	$ 0.7	$ 0.7	$ 2.2
Tax expense on unrealized net gain on derivatives	$ 0.0	$ 0.0	$ 0.2	$ (0.1)