Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement [Abstract]
Net sales	$ 1,536.5	$ 1,401.0
Cost of sales	(1,198.0)	(1,102.0)
Gross profit	338.5	299.0
Selling, general, and administrative expenses	(128.4)	(114.3)
Other expense, net	(7.0)	(3.9)
Income from operations	203.1	180.8
Interest expense, net	(24.0)	(21.6)
Income before taxes	179.1	159.2
Income tax provision	(61.7)	(55.5)
Net income	$ 117.4	$ 103.7
Net income per common share:
Basic (in dollars per share)	$ 1.25	$ 1.09
Diluted (in dollars per share)	1.24	1.09
Dividends declared per common share (in dollars per share)	$ 0.63	$ 0.55
Statements of Comprehensive Income:
Net income	$ 117.4	$ 103.7
Foreign currency translation adjustment	(0.2)	0.0
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.5 million and $0.5 million	0.9	0.9
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $1.2 million and $1.0 million	2.2	1.6
Other comprehensive income	2.9	2.5
Comprehensive income	$ 120.3	$ 106.2