Acquisition - Supplemental Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition, Pro Forma Information [Abstract]
Net sales	$ 4,310.7	$ 3,993.9	$ 11,615.6	$ 10,692.6
Net income	$ 13.7	$ 13.5	$ 22.7	$ 35.5
Basic net income per common share (in dollars per share)	$ 0.29	$ 0.29	$ 0.49	$ 0.77
Diluted net income per common share (in dollars per share)	$ 0.29	$ 0.29	$ 0.49	$ 0.76
Farner-Bocken Company
Business Acquisition, Pro Forma Information [Abstract]
Net sales	$ 4,310.7	$ 4,356.2	$ 12,355.9	$ 11,702.0
Net income	$ 13.9	$ 16.8	$ 27.6	$ 42.5
Basic earnings per share (in dollars per share)	$ 0.30	$ 0.36	$ 0.60	$ 0.92
Diluted earnings per share (in dollars per share)	$ 0.30	$ 0.36	$ 0.59	$ 0.91