Selected Condensed Consolidating Financial Statements of Parent, Issuer, Guarantors and Non-Guarantors - Condensed Consolidating Statements of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Condensed Income Statements Captions [Line Items]
Net sales	$ 4,236.3	$ 4,690.0	$ 13,107.3	$ 13,637.4
Cost of goods sold	3,466.3	3,701.1	10,723.5	10,967.1
Gross profit	770.0	988.9	2,383.8	2,670.3
Selling, general and administrative, excluding intangible amortization	390.1	442.4	1,234.4	1,287.4
Selling, general and administrative intangible amortization	99.6	102.4	301.5	297.7
(Gain) loss on disposal of assets	1.0	6.5	(5.9)	(37.3)
Multiemployer pension withdrawal income	(2.0)	(1.7)	(1.1)	(1.7)
Land and Development impairments				13.0
Restructuring and other costs	9.7	17.9	56.2	107.1
Operating profit	271.6	421.4	798.7	1,004.1
Interest (expense) income, net	(92.4)	(111.1)	(283.2)	(317.3)
Loss on extinguishment of debt	(0.6)	(3.2)	(1.1)	(4.7)
Pension and other postretirement non-service (expense) income	25.6	18.9	78.4	54.9
Other income (expense), net	(5.0)	3.7	(9.6)	(2.3)
Equity in income of unconsolidated entities		1.7	8.7	8.3
Income before income taxes	199.2	331.4	591.9	743.0
Income tax benefit (expense)	(19.2)	(77.6)	(123.5)	(187.5)
Consolidated net income	180.0	253.8	468.4	555.5
Less: Net income attributable to noncontrolling interests	(1.5)	(1.2)	(3.3)	(3.4)
Net income attributable to common stockholders	178.5	252.6	465.1	552.1
Comprehensive income (loss) attributable to common stockholders	210.1	282.7	220.3	552.0
Parent [Member]
Condensed Income Statements Captions [Line Items]
Other income (expense), net			0.1
Equity in income (loss) of consolidated entities	178.5	252.6	465.0	552.1
Income before income taxes	178.5	252.6	465.1	552.1
Consolidated net income	178.5	252.6	465.1	552.1
Net income attributable to common stockholders	178.5	252.6	465.1	552.1
Comprehensive income (loss) attributable to common stockholders	210.1	282.7	220.3	552.0
Issuer [Member]
Condensed Income Statements Captions [Line Items]
Selling, general and administrative, excluding intangible amortization	0.4	(0.4)	0.7
Restructuring and other costs		1.4	3.6	5.3
Operating profit	(0.4)	(1.0)	(4.3)	(5.3)
Interest (expense) income, net	(60.6)	(66.5)	(189.1)	(178.5)
Intercompany interest income (expense), net	(1.5)	(2.5)	(8.3)	1.0
Loss on extinguishment of debt	(0.6)	(0.8)	(1.0)	(2.6)
Other income (expense), net	0.5		0.5	(4.0)
Equity in income (loss) of consolidated entities	272.7	276.9	751.6	671.1
Income before income taxes	210.1	206.1	549.4	481.7
Income tax benefit (expense)	15.6	17.9	50.4	46.9
Consolidated net income	225.7	224.0	599.8	528.6
Net income attributable to common stockholders	225.7	224.0	599.8	528.6
Comprehensive income (loss) attributable to common stockholders	257.2	253.7	355.9	530.6
Guarantor Subsidiaries [Member]
Condensed Income Statements Captions [Line Items]
Net sales	604.9	643.0	1,825.1	1,906.0
Cost of goods sold	485.3	475.6	1,469.1	1,503.3
Gross profit	119.6	167.4	356.0	402.7
Selling, general and administrative, excluding intangible amortization	18.6	26.0	75.3	53.3
Selling, general and administrative intangible amortization	24.5	26.1	75.0	78.4
(Gain) loss on disposal of assets	(0.1)	0.1	(0.1)	0.1
Multiemployer pension withdrawal income	(2.0)		(1.9)
Restructuring and other costs		0.1		0.2
Operating profit	78.6	115.1	207.7	270.7
Interest (expense) income, net	(33.5)	(36.9)	(102.3)	(128.8)
Intercompany interest income (expense), net	(17.8)	(33.3)	(67.2)	(87.9)
Loss on extinguishment of debt		(2.3)		(1.9)
Pension and other postretirement non-service (expense) income	(1.4)	(1.4)	(5.2)	(4.8)
Other income (expense), net		(35.2)	1.3	(35.6)
Equity in income (loss) of consolidated entities	195.8	(11.4)	445.2	403.0
Income before income taxes	221.7	(5.4)	479.5	414.7
Income tax benefit (expense)	(0.6)	(1.9)	(2.3)	(3.2)
Consolidated net income	221.1	(7.3)	477.2	411.5
Net income attributable to common stockholders	221.1	(7.3)	477.2	411.5
Comprehensive income (loss) attributable to common stockholders	250.2	20.7	238.6	415.9
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements Captions [Line Items]
Net sales	4,293.6	4,676.3	13,233.2	13,648.2
Cost of goods sold	3,635.4	3,844.9	11,181.4	11,370.7
Gross profit	658.2	831.4	2,051.8	2,277.5
Selling, general and administrative, excluding intangible amortization	371.1	416.8	1,158.4	1,234.1
Selling, general and administrative intangible amortization	75.1	76.3	226.5	219.3
(Gain) loss on disposal of assets	1.1	6.4	(5.8)	(37.4)
Multiemployer pension withdrawal income		(1.7)	0.8	(1.7)
Land and Development impairments				13.0
Restructuring and other costs	9.7	16.4	52.6	101.6
Operating profit	201.2	317.2	619.3	748.6
Interest (expense) income, net	1.7	(7.7)	8.2	(10.0)
Intercompany interest income (expense), net	11.5	25.9	51.5	77.0
Loss on extinguishment of debt		(0.1)	(0.1)	(0.2)
Pension and other postretirement non-service (expense) income	27.0	20.3	83.6	59.7
Other income (expense), net	(5.5)	38.9	(11.5)	37.3
Equity in income of unconsolidated entities		1.7	8.7	8.3
Income before income taxes	235.9	396.2	759.7	920.7
Income tax benefit (expense)	(34.2)	(93.6)	(171.6)	(231.2)
Consolidated net income	201.7	302.6	588.1	689.5
Less: Net income attributable to noncontrolling interests	(1.5)	(1.2)	(3.3)	(3.4)
Net income attributable to common stockholders	200.2	301.4	584.8	686.1
Comprehensive income (loss) attributable to common stockholders	231.3	331.8	347.4	687.0
Eliminations [Member]
Condensed Income Statements Captions [Line Items]
Net sales	(662.2)	(629.3)	(1,951.0)	(1,916.8)
Cost of goods sold	(654.4)	(619.4)	(1,927.0)	(1,906.9)
Gross profit	(7.8)	(9.9)	(24.0)	(9.9)
Operating profit	(7.8)	(9.9)	(24.0)	(9.9)
Intercompany interest income (expense), net	7.8	9.9	24.0	9.9
Equity in income (loss) of consolidated entities	(647.0)	(518.1)	(1,661.8)	(1,626.2)
Income before income taxes	(647.0)	(518.1)	(1,661.8)	(1,626.2)
Consolidated net income	(647.0)	(518.1)	(1,661.8)	(1,626.2)
Net income attributable to common stockholders	(647.0)	(518.1)	(1,661.8)	(1,626.2)
Comprehensive income (loss) attributable to common stockholders	$ (738.7)	$ (606.2)	$ (941.9)	$ (1,633.5)