Consolidated Statements of Income and Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net sales	$ 1,541.6	$ 1,759.9	$ 3,250.3	$ 3,493.6
Cost of sales	(1,215.8)	(1,332.0)	(2,559.6)	(2,644.3)
Gross profit	325.8	427.9	690.7	849.3
Selling, general and administrative expenses	(136.3)	(143.7)	(282.2)	(283.7)
Goodwill impairment	(55.2)		(55.2)
Other expense, net	(18.2)	(3.8)	(28.1)	(9.8)
Income from operations	116.1	280.4	325.2	555.8
Non-operating pension income (expense)	0.6	(2.0)	1.1	(4.1)
Interest expense, net	(25.1)	(22.4)	(44.6)	(46.4)
Income before taxes	91.6	256.0	281.7	505.3
Provision for income taxes	(34.9)	(62.4)	(83.4)	(124.9)
Net income	$ 56.7	$ 193.6	$ 198.3	$ 380.4
Net income per common share:
Basic	$ 0.60	$ 2.05	$ 2.09	$ 4.03
Diluted	0.59	2.04	2.08	4.02
Dividends declared per common share	$ 0.79	$ 0.79	$ 1.58	$ 1.58
Statements of Comprehensive Income:
Net income	$ 56.7	$ 193.6	$ 198.3	$ 380.4
Reclassification adjustments to cash flow hedges included in net income, net of tax of $0.0 million, $0.3 million, $0.0 million, and $0.7 million		1.0		1.9
Changes in unrealized gains on marketable debt securities, net of tax of $0.3 million, $0.0 million, $0.2 million, and $0.0 million	0.9		0.7
Amortization of pension and postretirement plans actuarial loss and prior service cost, net of tax of $0.9 million, $0.8 million, $1.8 million, and $1.6 million	2.7	2.3	5.4	4.7
Other comprehensive income	3.6	3.3	6.1	6.6
Comprehensive income	$ 60.3	$ 196.9	$ 204.4	$ 387.0