Selected Condensed Consolidating Financial Statements of Parent, Issuer, Guarantors and Non-Guarantors - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019
Current Assets:
Cash and cash equivalents	$ 640.2	$ 151.6
Accounts receivable	2,222.1	2,193.2
Inventories	2,125.4	2,107.5
Other current assets	501.2	496.2
Assets held for sale	3.3	25.8
Total current assets	5,492.2	4,974.3
Property, plant and equipment, net	11,036.3	11,189.5
Goodwill	7,264.0	7,285.6
Intangibles, net	3,845.9	4,059.5
Restricted assets held by special purpose entities	1,270.9	1,274.3
Prepaid pension asset	278.6	224.7
Other assets	1,772.4	1,148.8
Total Assets	30,960.3	30,156.7
Current liabilities:
Current portion of debt	432.0	561.1
Accounts payable	1,696.4	1,831.8
Accrued compensation and benefits	381.5	470.4
Other current liabilities	629.9	571.8
Total current liabilities	3,139.8	3,435.1
Long-term debt due after one year	10,424.6	9,502.3
Pension liabilities, net of current portion	274.1	294.0
Postretirement benefit liabilities, net of current portion	152.3	162.1
Non-recourse liabilities held by special purpose entities	1,140.9	1,145.2
Deferred income taxes	2,878.4	2,878.0
Other long-term liabilities	1,450.6	1,053.9
Redeemable noncontrolling interests	1.6	1.9
Total stockholders’ equity	11,482.4	11,669.9	$ 11,640.8
Noncontrolling interests	15.6	14.3
Total equity	11,498.0	11,684.2	$ 11,653.6
Total Liabilities and Equity	30,960.3	30,156.7
Parent [Member]
Current Assets:
Other current assets	0.4
Total current assets	0.4
Investments in consolidated subsidiaries	11,983.4	11,973.6
Total Assets	11,983.8	11,973.6
Current liabilities:
Accrued compensation and benefits	0.2	0.3
Intercompany payables	501.2	303.4
Total current liabilities	501.4	303.7
Total stockholders’ equity	11,482.4	11,669.9
Total equity	11,482.4	11,669.9
Total Liabilities and Equity	11,983.8	11,973.6
Issuer [Member]
Current Assets:
Cash and cash equivalents	0.2
Other current assets		1.2
Intercompany receivables	378.1	227.7
Total current assets	378.3	228.9
Intercompany notes receivable	155.0	155.0
Investments in consolidated subsidiaries	18,703.0	18,524.2
Other assets	69.1	67.8
Total Assets	19,305.4	18,975.9
Current liabilities:
Current portion of debt	179.5	135.3
Accounts payable	1.4	0.7
Other current liabilities	23.9	18.6
Intercompany payables	29.8
Total current liabilities	234.6	154.6
Long-term debt due after one year	6,761.1	6,608.0
Intercompany notes payable	636.3	636.3
Other long-term liabilities	12.4	12.9
Total stockholders’ equity	11,661.0	11,564.1
Total equity	11,661.0	11,564.1
Total Liabilities and Equity	19,305.4	18,975.9
Guarantor Subsidiaries [Member]
Current Assets:
Cash and cash equivalents	469.6	17.8
Accounts receivable	26.7	31.1
Inventories	266.2	254.3
Other current assets	7.2	11.8
Intercompany receivables	1.7
Total current assets	771.4	315.0
Property, plant and equipment, net	15.1	18.9
Goodwill	1,158.6	1,158.6
Intangibles, net	1,434.5	1,485.0
Intercompany notes receivable	170.6	156.9
Investments in consolidated subsidiaries	20,161.8	20,103.6
Other assets	241.3	185.3
Total Assets	23,953.3	23,423.3
Current liabilities:
Current portion of debt	106.1	108.9
Accounts payable	33.3	31.3
Accrued compensation and benefits	14.4	14.5
Other current liabilities	77.6	83.8
Intercompany payables	1,583.1	1,052.9
Total current liabilities	1,814.5	1,291.4
Long-term debt due after one year	1,975.6	1,982.9
Intercompany notes payable	2,390.5	2,390.5
Pension liabilities, net of current portion	142.9	147.6
Postretirement benefit liabilities, net of current portion	25.3	25.7
Deferred income taxes	265.8	278.9
Other long-term liabilities	176.5	131.2
Total stockholders’ equity	17,162.2	17,175.1
Total equity	17,162.2	17,175.1
Total Liabilities and Equity	23,953.3	23,423.3
Non-Guarantor Subsidiaries [Member]
Current Assets:
Cash and cash equivalents	170.4	133.8
Accounts receivable	2,229.1	2,201.7
Inventories	1,859.2	1,853.2
Other current assets	493.6	483.2
Intercompany receivables	1,779.2	1,128.6
Assets held for sale	3.3	25.8
Total current assets	6,534.8	5,826.3
Property, plant and equipment, net	11,021.2	11,170.6
Goodwill	6,105.4	6,127.0
Intangibles, net	2,411.4	2,574.5
Restricted assets held by special purpose entities	1,270.9	1,274.3
Prepaid pension asset	278.6	224.7
Intercompany notes receivable	3,026.8	3,026.8
Other assets	1,553.8	971.8
Total Assets	32,202.9	31,196.0
Current liabilities:
Current portion of debt	146.4	316.9
Accounts payable	1,695.4	1,839.4
Accrued compensation and benefits	366.9	455.6
Other current liabilities	528.4	469.4
Intercompany payables	44.9
Total current liabilities	2,782.0	3,081.3
Long-term debt due after one year	1,687.9	911.4
Intercompany notes payable	325.6	311.9
Pension liabilities, net of current portion	131.2	146.4
Postretirement benefit liabilities, net of current portion	127.0	136.4
Non-recourse liabilities held by special purpose entities	1,140.9	1,145.2
Deferred income taxes	2,704.4	2,675.2
Other long-term liabilities	1,261.7	909.8
Redeemable noncontrolling interests	1.6	1.9
Total stockholders’ equity	22,025.0	21,862.2
Noncontrolling interests	15.6	14.3
Total equity	22,040.6	21,876.5
Total Liabilities and Equity	32,202.9	31,196.0
Eliminations [Member]
Current Assets:
Accounts receivable	(33.7)	(39.6)
Intercompany receivables	(2,159.0)	(1,356.3)
Total current assets	(2,192.7)	(1,395.9)
Intercompany notes receivable	(3,352.4)	(3,338.7)
Investments in consolidated subsidiaries	(50,848.2)	(50,601.4)
Other assets	(91.8)	(76.1)
Total Assets	(56,485.1)	(55,412.1)
Current liabilities:
Accounts payable	(33.7)	(39.6)
Intercompany payables	(2,159.0)	(1,356.3)
Total current liabilities	(2,192.7)	(1,395.9)
Intercompany notes payable	(3,352.4)	(3,338.7)
Deferred income taxes	(91.8)	(76.1)
Total stockholders’ equity	(50,848.2)	(50,601.4)
Total equity	(50,848.2)	(50,601.4)
Total Liabilities and Equity	$ (56,485.1)	$ (55,412.1)