Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Statement [Abstract]
Net sales	$ 1,401.0	$ 1,425.7
Cost of sales	(1,102.4)	(1,148.7)
Gross profit	298.6	277.0
Selling, general, and administrative expenses	(113.9)	(117.3)
Other expense, net	(3.9)	(2.6)
Income from operations	180.8	157.1
Interest expense, net	(21.6)	(19.2)
Income before taxes	159.2	137.9
Income tax provision	(55.5)	(47.1)
Net income	$ 103.7	$ 90.8
Net income per common share:
Basic (in dollars per share)	$ 1.09	$ 0.92
Diluted (in dollars per share)	1.09	0.92
Dividends declared per common share (in US$ per share)	$ 0.55	$ 0.55
Statements of Comprehensive Income:
Net income	$ 103.7	$ 90.8
Foreign currency translation adjustment	0.0	(1.4)
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.5 million and $0.6 million	0.9	0.8
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $1.0 million and $1.4 million	1.6	2.2
Other comprehensive income	2.5	1.6
Comprehensive income	$ 106.2	$ 92.4