CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY (UNAUDITED) - USD ($) shares in Thousands, $ in Millions	Total	Directors	Greif, Inc. Equity	Greif, Inc. Equity Directors	Common Stock	Common Stock Directors	Treasury Stock	Treasury Stock Directors	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non controlling interests
Beginning balance (in shares) at Sep. 30, 2024					47,181
Beginning balance at Sep. 30, 2024	$ 2,134.3		$ 2,088.3		$ 229.7		$ (279.0)		$ 2,485.2	$ (347.6)	$ 46.0
Beginning balance (in shares) at Sep. 30, 2024							29,661
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	73.1		61.9						61.9		11.2
Other comprehensive income (loss):
Foreign currency translation, net of income tax benefit (expense)	(33.2)		(32.9)							(32.9)	(0.3)
Derivative financial instruments, net of income tax benefit (expense)	30.3		30.3							30.3
Minimum pension liability adjustment, net of income tax (expense) benefit	2.1		2.1							2.1
Comprehensive income	72.3		61.4
Current period mark to redemption value of redeemable noncontrolling interest and other	(3.5)		(3.5)						(3.5)
Net income allocated to redeemable noncontrolling interests	(3.9)										(3.9)
Dividends paid to Greif, Inc. shareholders	(62.4)		(62.4)						(62.4)
Dividends paid to noncontrolling interests and other	(11.5)										(11.5)
Dividends earned on RSU shares	(0.1)		(0.1)						(0.1)
Colleague stock purchase plan (in shares)					45		(45)
Colleague stock purchase plan	2.7		2.7		$ 2.4		$ 0.3
Long-term incentive shares issued (in shares)					211		(211)
Long-term incentive shares issued	8.4		8.4		$ 6.7		$ 1.7
Share based compensation	2.5		2.5		$ 2.5
Restricted stock, directors (in shares)						24		(24)
Restricted stock, directors		$ 1.5		$ 1.5		$ 1.3		$ 0.2
Ending balance (in shares) at Mar. 31, 2025					47,461
Ending balance at Mar. 31, 2025	2,140.3		2,098.8		$ 242.6		$ (276.8)		2,481.1	(348.1)	41.5
Ending balance (in shares) at Mar. 31, 2025							29,381
Beginning balance (in shares) at Dec. 31, 2024					47,181
Beginning balance at Dec. 31, 2024	2,077.1		2,040.0		$ 231.4		$ (279.0)		2,473.4	(385.8)	37.1
Beginning balance (in shares) at Dec. 31, 2024							29,661
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46.4		39.9						39.9		6.5
Other comprehensive income (loss):
Foreign currency translation, net of income tax benefit (expense)	60.8		60.3							60.3	0.5
Derivative financial instruments, net of income tax benefit (expense)	(21.2)		(21.2)							(21.2)
Minimum pension liability adjustment, net of income tax (expense) benefit	(1.4)		(1.4)							(1.4)
Comprehensive income	84.6		77.6
Current period mark to redemption value of redeemable noncontrolling interest and other	(0.9)		(0.9)						(0.9)
Net income allocated to redeemable noncontrolling interests	(2.0)										(2.0)
Dividends paid to Greif, Inc. shareholders	(31.4)		(31.4)						(31.4)
Dividends paid to noncontrolling interests and other	(0.6)										(0.6)
Dividends earned on RSU shares	0.1		0.1						0.1
Colleague stock purchase plan (in shares)					45		(45)
Colleague stock purchase plan	2.5		2.5		$ 2.2		$ 0.3
Long-term incentive shares issued (in shares)					211		(211)
Long-term incentive shares issued	8.4		8.4		$ 6.7		$ 1.7
Share based compensation	1.0		1.0		$ 1.0
Restricted stock, directors (in shares)						24		(24)
Restricted stock, directors		1.5		1.5		$ 1.3		$ 0.2
Ending balance (in shares) at Mar. 31, 2025					47,461
Ending balance at Mar. 31, 2025	2,140.3		2,098.8		$ 242.6		$ (276.8)		2,481.1	(348.1)	41.5
Ending balance (in shares) at Mar. 31, 2025							29,381
Beginning balance (in shares) at Sep. 30, 2025					47,501
Beginning balance at Sep. 30, 2025	2,952.4		2,914.9		$ 247.3		$ (276.5)		3,194.9	(250.8)	37.5
Beginning balance (in shares) at Sep. 30, 2025							29,341
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	197.2		187.2						187.2		10.0
Other comprehensive income (loss):
Foreign currency translation, net of income tax benefit (expense)	(5.1)		(4.6)							(4.6)	(0.5)
Derivative financial instruments, net of income tax benefit (expense)	(0.9)		(0.9)							(0.9)
Minimum pension liability adjustment, net of income tax (expense) benefit	2.1		2.1							2.1
Comprehensive income	193.3		183.8
Current period mark to redemption value of redeemable noncontrolling interest and other	(1.1)		(1.1)						(1.1)
Net income allocated to redeemable noncontrolling interests	(2.5)										(2.5)
Dividends paid to Greif, Inc. shareholders	(63.6)		(63.6)						(63.6)
Dividends paid to noncontrolling interests and other	(5.5)										(5.5)
Dividends earned on RSU shares	(0.1)		(0.1)						(0.1)
Colleague stock purchase plan (in shares)					33		(33)
Colleague stock purchase plan	2.4		2.4		$ 1.9		$ 0.5
Share repurchases (in shares)					(2,153)		2,153
Share repurchases	(148.6)		(148.6)		$ 0.5		$ (149.1)
Long-term incentive shares issued (in shares)					231		(231)
Long-term incentive shares issued	10.8		10.8		$ 7.6		$ 3.2
Share based compensation	2.2		2.2		$ 2.2
Share donation (in shares)					537		(537)
Share donation	40.0		40.0		$ 33.3		$ 6.7
Restricted stock, directors (in shares)						19		(19)
Restricted stock, directors		0.6		0.6		$ 0.3		$ 0.3
Deferrals of director shares in Rabbi Trust		0.9		0.9		$ 0.9
Ending balance (in shares) at Mar. 31, 2026					46,168
Ending balance at Mar. 31, 2026	2,981.2		2,942.2		$ 294.0		$ (414.9)		3,317.3	(254.2)	39.0
Ending balance (in shares) at Mar. 31, 2026							30,674
Beginning balance (in shares) at Dec. 31, 2025					45,577
Beginning balance at Dec. 31, 2025	2,978.5		2,941.1		$ 249.3		$ (406.4)		3,337.1	(238.9)	37.4
Beginning balance (in shares) at Dec. 31, 2025							31,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16.3		12.6						12.6		3.7
Other comprehensive income (loss):
Foreign currency translation, net of income tax benefit (expense)	(17.4)		(16.9)							(16.9)	(0.5)
Derivative financial instruments, net of income tax benefit (expense)	(0.1)		(0.1)							(0.1)
Minimum pension liability adjustment, net of income tax (expense) benefit	1.7		1.7							1.7
Comprehensive income	0.5		(2.7)
Current period mark to redemption value of redeemable noncontrolling interest and other	(0.5)		(0.5)						(0.5)
Net income allocated to redeemable noncontrolling interests	(1.1)										(1.1)
Dividends paid to Greif, Inc. shareholders	(31.9)		(31.9)						(31.9)
Dividends paid to noncontrolling interests and other	(0.5)										(0.5)
Colleague stock purchase plan (in shares)					33		(33)
Colleague stock purchase plan	2.1		2.1		$ 1.6		$ 0.5
Share repurchases (in shares)					(229)		229
Share repurchases	(19.2)		(19.2)		$ 0.0		$ (19.2)
Long-term incentive shares issued (in shares)					231		(231)
Long-term incentive shares issued	10.8		10.8		$ 7.6		$ 3.2
Share based compensation	1.0		1.0		$ 1.0
Share donation (in shares)					537		(537)
Share donation	40.0		40.0		$ 33.3		$ 6.7
Restricted stock, directors (in shares)						19		(19)
Restricted stock, directors		0.6		0.6		$ 0.3		$ 0.3
Deferrals of director shares in Rabbi Trust		$ 0.9		$ 0.9		$ 0.9
Ending balance (in shares) at Mar. 31, 2026					46,168
Ending balance at Mar. 31, 2026	$ 2,981.2		$ 2,942.2		$ 294.0		$ (414.9)		$ 3,317.3	$ (254.2)	$ 39.0
Ending balance (in shares) at Mar. 31, 2026							30,674