CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Statement of Comprehensive Income [Abstract]
Consolidated net income (loss)	$ 16.4	$ (2,004.8)	$ (6.3)	$ (1,958.0)
Foreign currency translation adjustments:
Foreign currency translation (loss) gain	(22.2)	182.8	136.6	300.3
Reclassification of previously unrealized net foreign currency loss upon consolidation of equity investment				29.0
Derivatives:
Deferred loss on cash flow hedges	(6.8)	(23.5)	(18.4)	(45.3)
Reclassification adjustment of net loss on cash flow hedges included in earnings	9.1	20.1	13.0	30.0
Defined benefit pension and other postretirement benefit plans:
Amortization and settlement recognition of net actuarial loss, included in pension and postretirement cost	5.1	10.1	10.0	19.8
Amortization and curtailment recognition of prior service cost, included in pension and postretirement cost	1.6	1.4	2.7	2.8
Other comprehensive (loss) income, net of tax	(13.2)	190.9	143.9	336.6
Comprehensive income (loss)	3.2	(1,813.9)	137.6	(1,621.4)
Less: Comprehensive income attributable to noncontrolling interests	(0.9)	(1.8)	(0.6)	(3.6)
Comprehensive income (loss) attributable to common stockholders	$ 2.3	$ (1,815.7)	$ 137.0	$ (1,625.0)