EQUITY AND COMPREHENSIVE INCOME (LOSS) - Summary of Changes in Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,135.2	$ 1,136.4	$ 1,191.1	$ 1,154.2
Net income	24.4	67.5	76.3	124.4
Other comprehensive income (loss):
Foreign currency translation	59.6	(0.9)	4.2	(10.4)
Derivative financial instruments, net of income tax benefit	2.0	(5.0)	(20.9)	(20.7)
Minimum pension liabilities	(2.4)	2.3	20.6	2.2
Comprehensive income	83.6	63.9	80.2	95.5
Current period mark to redemption value of redeemable noncontrolling interest	1.1	2.3	2.2	3.3
Net income allocated to redeemable noncontrolling interests	0.3	(0.5)	0.2	(1.8)
Dividends paid to Greif, Inc. shareholders	(26.2)	(26.1)	(78.2)	(77.9)
Dividends paid to noncontrolling interests and other	(3.6)	(0.4)	(12.1)	(8.3)
Long-term incentive shares issued			5.3	11.6
Share based compensation	0.5		1.0
Restricted stock				1.1
Ending balance	1,190.9	1,175.6	1,190.9	1,175.6
Derivative, income tax benefit	$ 6.7	$ 2.2	6.7
Pension, income tax benefit			7.5	3.4
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				$ (2.1)
Executive
Other comprehensive income (loss):
Restricted stock			0.2
Directors
Other comprehensive income (loss):
Restricted stock			$ 1.0
Capital Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (shares)	48,450	48,266	48,266	47,949
Beginning balance	$ 169.2	$ 162.6	$ 162.6	$ 150.5
Other comprehensive income (loss):
Long-term incentive shares issued (shares)			153	292
Long-term incentive shares issued			$ 5.0	$ 11.0
Share based compensation	$ 0.5		$ 1.0
Restricted stock (shares)				25
Restricted stock				$ 1.1
Ending balance (shares)	48,450	48,266	48,450	48,266
Ending balance	$ 169.7	$ 162.6	$ 169.7	$ 162.6
Capital Stock | Executive
Other comprehensive income (loss):
Restricted stock (shares)			3
Restricted stock			$ 0.1
Capital Stock | Directors
Other comprehensive income (loss):
Restricted stock (shares)			28
Restricted stock			$ 1.0
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (shares)	28,392	28,576	28,576	28,893
Beginning balance	$ (134.4)	$ (134.8)	$ (134.8)	$ (135.4)
Other comprehensive income (loss):
Long-term incentive shares issued (shares)			(153)	(292)
Long-term incentive shares issued			$ 0.3	$ 0.6
Restricted stock (shares)				(25)
Restricted stock
Ending balance (shares)	28,392	28,576	28,392	28,576
Ending balance	$ (134.4)	$ (134.8)	$ (134.4)	$ (134.8)
Treasury Stock | Executive
Other comprehensive income (loss):
Restricted stock (shares)			(3)
Restricted stock			$ 0.1
Treasury Stock | Directors
Other comprehensive income (loss):
Restricted stock (shares)			(28)
Restricted stock			$ 0.0
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,531.8	1,460.2	1,539.0	1,469.8
Net income	20.7	62.7	64.4	106.0
Other comprehensive income (loss):
Current period mark to redemption value of redeemable noncontrolling interest	1.1	2.3	2.2	3.3
Dividends paid to Greif, Inc. shareholders	(26.2)	(26.1)	(78.2)	(77.9)
Ending balance	1,527.4	1,499.1	1,527.4	1,499.1
Retained Earnings | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				(2.1)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(483.4)	(401.4)	(433.7)	(377.1)
Other comprehensive income (loss):
Foreign currency translation	62.4	(2.2)	12.6	(10.7)
Derivative financial instruments, net of income tax benefit	2.0	(5.0)	(20.9)	(20.7)
Minimum pension liabilities	(2.4)	2.3	20.6	2.2
Ending balance	(421.4)	(406.3)	(421.4)	(406.3)
Greif, Inc. Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,083.2	1,086.6	1,133.1	1,107.8
Net income	20.7	62.7	64.4	106.0
Other comprehensive income (loss):
Foreign currency translation	62.4	(2.2)	12.6	(10.7)
Derivative financial instruments, net of income tax benefit	2.0	(5.0)	(20.9)	(20.7)
Minimum pension liabilities	(2.4)	2.3	20.6	2.2
Comprehensive income	82.7	57.8	76.7	76.8
Current period mark to redemption value of redeemable noncontrolling interest	1.1	2.3	2.2	3.3
Dividends paid to Greif, Inc. shareholders	(26.2)	(26.1)	(78.2)	(77.9)
Long-term incentive shares issued			5.3	11.6
Share based compensation	0.5		1.0
Restricted stock				1.1
Ending balance	1,141.3	1,120.6	1,141.3	1,120.6
Greif, Inc. Equity | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance				(2.1)
Greif, Inc. Equity | Executive
Other comprehensive income (loss):
Restricted stock			0.2
Greif, Inc. Equity | Directors
Other comprehensive income (loss):
Restricted stock			1.0
Non controlling interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	52.0	49.8	58.0	46.4
Net income	3.7	4.8	11.9	18.4
Other comprehensive income (loss):
Foreign currency translation	(2.8)	1.3	(8.4)	0.3
Net income allocated to redeemable noncontrolling interests	0.3	(0.5)	0.2	(1.8)
Dividends paid to noncontrolling interests and other	(3.6)	(0.4)	(12.1)	(8.3)
Ending balance	$ 49.6	$ 55.0	$ 49.6	$ 55.0
Class A Common Stock
Other comprehensive income (loss):
Cash dividends declared per common share (usd per share)	$ 0.44	$ 0.44	$ 1.32	$ 1.32
Class B Common Stock
Other comprehensive income (loss):
Cash dividends declared per common share (usd per share)	$ 0.66	$ 0.66	$ 1.97	$ 1.97