Condensed Consolidated Statements of Comprehensive Income (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]
Adjustment to pension and other benefit plans, tax impact	$ (0.9)	$ (1.1)	$ (2.8)	$ (3.6)
Unrealized gain or loss on investment, tax impact	(0.3)	0.1	(0.7)	(0.1)
Other Comprehensive Income, Unrealized Gain (loss) on derivatives arising during the period, tax	$ 0.5	$ (0.2)	$ 0.9	$ 0.8