Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Net sales	$ 1,584.0	$ 1,417.4	$ 3,120.5	$ 2,818.4
Cost of sales	(1,219.4)	(1,097.3)	(2,417.3)	(2,199.3)
Gross profit	364.6	320.1	703.2	619.1
Selling, general, and administrative expenses	(130.2)	(114.8)	(258.7)	(229.1)
Other expense, net	(0.6)	(5.1)	(7.6)	(9.0)
Income from operations	233.8	200.2	436.9	381.0
Interest expense, net	(25.2)	(22.5)	(49.2)	(44.1)
Income before taxes	208.6	177.7	387.7	336.9
Provision for income taxes	(65.4)	(61.8)	(127.1)	(117.3)
Net income	$ 143.2	$ 115.9	$ 260.6	$ 219.6
Net income per common share:
Basic	$ 1.52	$ 1.23	$ 2.76	$ 2.32
Diluted	1.52	1.23	2.76	2.32
Dividends declared per common share	$ 0.63	$ 0.55	$ 1.26	$ 1.10
Statements of Comprehensive Income:
Net income	$ 143.2	$ 115.9	$ 260.6	$ 219.6
Foreign currency translation adjustment	(0.1)	0.0	(0.3)	0.0
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.6 million, $0.6 million, $1.2 million, and $1.1 million	0.8	0.8	1.6	1.7
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $1.2 million, $1.0 million, $2.3 million, and $2.0 million	2.1	1.6	4.3	3.2
Changes in unfunded employee benefit obligation net of tax of $0.0 million, $2.0 million, $0.0 million and $2.0 million		3.1		3.1
Other comprehensive income	2.8	5.5	5.6	8.0
Comprehensive income	$ 146.0	$ 121.4	$ 266.2	$ 227.6