CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Statement of Comprehensive Income [Abstract]
Net income	$ 16.3	$ 46.4	$ 197.2	$ 73.1
Other comprehensive income (loss), net of tax:
Foreign currency translation	(17.4)	60.8	(5.1)	(33.2)
Derivative financial instruments	(0.1)	(21.2)	(0.9)	30.3
Minimum pension liabilities	1.7	(1.4)	2.1	2.1
Other comprehensive income (loss), net of tax	(15.8)	38.2	(3.9)	(0.8)
Comprehensive income	0.5	84.6	193.3	72.3
Comprehensive income attributable to noncontrolling interests	3.2	7.0	9.5	10.9
Comprehensive (loss) income attributable to Greif, Inc.	$ (2.7)	$ 77.6	$ 183.8	$ 61.4