Selected Condensed Consolidating Financial Statements of Parent, Issuer, Guarantors and Non-Guarantors - Noncash Operating, Investing and Financing Activities (Details) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Parent [Member]
Operating activities:
Intercompany receivables		$ (140.9)
Investing activities:
Intercompany capital investment	$ (407.3)	(10,396.2)
Intercompany return of capital	442.0	606.7
Financing activities:
Intercompany capital distribution		(563.0)
Issuer [Member]
Investing activities:
Intercompany notes issued		(3,800.0)
Intercompany notes proceeds		4,519.8
Intercompany capital investment	(625.6)	(5,895.5)
Intercompany return of capital	21.2	1,479.6
Financing activities:
Intercompany notes borrowing	117.0	4,436.3
Intercompany capital receipt		10,396.2
Intercompany capital distribution	(442.0)	(606.7)
Guarantor Subsidiaries [Member]
Investing activities:
Intercompany notes issued	(63.6)	(4,666.4)
Intercompany notes proceeds	65.8	4,519.8
Intercompany capital investment	(917.8)	(6,880.5)
Intercompany return of capital	619.7	1,021.4
Financing activities:
Intercompany notes borrowing		479.1
Intercompany notes payments	(322.5)	(959.6)
Intercompany capital receipt	625.2	5,413.7
Intercompany capital distribution	(21.2)	(457.5)
Intercompany dividends paid	(48.3)	(302.2)
Non-Guarantor Subsidiaries [Member]
Operating activities:
Intercompany payables		140.9
Investing activities:
Intercompany notes issued	(117.0)	(8,715.4)
Intercompany notes proceeds	322.5	4,759.6
Financing activities:
Intercompany notes borrowing	63.6	12,266.4
Intercompany notes payments	(65.8)	(12,839.6)
Intercompany capital receipt	1,325.5	7,362.3
Intercompany capital distribution	(619.7)	(1,480.5)
Intercompany dividends paid	(1,436.9)	(1,419.6)
Eliminations [Member]
Operating activities:
Intercompany receivables		140.9
Intercompany payables		(140.9)
Investing activities:
Intercompany notes issued	180.6	17,181.8
Intercompany notes proceeds	(388.3)	(13,799.2)
Intercompany capital investment	1,950.7	23,172.2
Intercompany return of capital	(1,082.9)	(3,107.7)
Financing activities:
Intercompany notes borrowing	(180.6)	(17,181.8)
Intercompany notes payments	388.3	13,799.2
Intercompany capital receipt	(1,950.7)	(23,172.2)
Intercompany capital distribution	1,082.9	3,107.7
Intercompany dividends paid	$ 1,485.2	$ 1,721.8