Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Net sales	$ 6,444.9		$ 5,779.0	$ 5,741.7
Cost of sales	(4,972.7)		(4,503.3)	(4,533.7)
Gross profit	1,472.2		1,275.7	1,208.0
Selling and administrative expenses	(522.6)		(471.1)	(451.3)
Other expense, net	(18.4)		(24.3)	(6.7)
Income from operations	931.2		780.3	750.0
Interest expense, net	(102.6)	[1]	(91.8)	(85.5)
Income before taxes	828.6		688.5	664.5
Provision for income taxes	(160.0)		(238.9)	(227.7)
Net income	$ 668.6		$ 449.6	$ 436.8
Net income per common share:
Basic	$ 7.09		$ 4.76	$ 4.47
Diluted	7.07		4.75	4.47
Dividends declared per common share	$ 2.52		$ 2.36	$ 2.20
Statements of Comprehensive Income:
Net income	$ 668.6		$ 449.6	$ 436.8
Foreign currency translation adjustment	(0.2)		0.0	2.7
Reclassification adjustments to cash flow hedges included in net income, net of tax of $2.2 million, $2.2 million, and $2.2 million for 2017, 2016, and 2015, respectively	3.5		3.5	3.5
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $4.9 million, $4.2 million, and $5.6 million for 2017, 2016, and 2015, respectively	8.2		6.7	8.8
Changes in unfunded employee benefit obligations, net of tax of $18.0 million, $15.7 million, and ($8.9) million for 2017, 2016, and 2015, respectively	(28.8)		(24.9)	14.0
Other comprehensive income (loss)	(17.3)		(14.7)	29.0
Comprehensive income	$ 651.3		$ 434.9	$ 465.8

[1] Includes $1.8 million of expense related to the write-off of deferred debt issuance costs in connection with the December 2017 debt refinancing.