CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Net sales	$ 4,447.3	$ 4,620.0	$ 8,871.0	$ 8,947.4
Cost of goods sold	3,642.5	3,720.4	7,257.2	7,266.0
Gross profit	804.8	899.6	1,613.8	1,681.4
Selling, general and administrative, excluding intangible amortization	418.6	444.1	844.3	845.0
Selling, general and administrative intangible amortization	100.1	102.4	201.9	195.3
Gain on disposal of assets	(5.6)		(6.9)	(43.8)
Multiemployer pension withdrawal expense	0.9		0.9
Land and Development impairments		13.0		13.0
Restructuring and other costs	16.4	34.8	46.5	89.2
Operating profit (loss)	274.4	305.3	527.1	582.7
Interest expense, net	(97.3)	(111.8)	(190.8)	(206.2)
(Loss) gain on extinguishment of debt	(0.5)	0.4	(0.5)	(1.5)
Pension and other postretirement non-service income	26.1	18.7	52.8	36.0
Other expense, net	(0.9)	(3.3)	(4.6)	(6.0)
Equity in income (loss) of unconsolidated entities	4.9	(0.2)	8.7	6.6
Income before income taxes	206.7	209.1	392.7	411.6
Income tax expense	(57.8)	(47.2)	(104.3)	(109.9)
Consolidated net income	148.9	161.9	288.4	301.7
Less: Net income attributable to noncontrolling interests	(0.8)	(1.5)	(1.8)	(2.2)
Net income attributable to common stockholders	$ 148.1	$ 160.4	$ 286.6	$ 299.5
Basic earnings per share attributable to common stockholders	$ 0.57	$ 0.63	$ 1.11	$ 1.17
Diluted earnings per share attributable to common stockholders	$ 0.57	$ 0.62	$ 1.10	$ 1.15
Basic weighted average shares outstanding	259.0	256.6	258.6	255.7
Diluted weighted average shares outstanding	260.2	259.4	260.1	259.4
Cash dividends paid per common share	$ 0.465	$ 0.455	$ 0.93	$ 0.91