EQUITY AND COMPREHENSIVE INCOME (LOSS) - Summary of Changes in Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2020	Apr. 30, 2019	Oct. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,222.7	$ 1,171.5	$ 1,191.1	$ 1,154.2
Net income	15.8	21.1	51.9	56.9
Other comprehensive income (loss):
Foreign currency translation	(52.3)	(14.7)	(55.4)	(9.5)
Derivative financial instruments, net of immaterial income tax expense	(23.1)	(10.0)	(22.9)	(15.7)
Derivative financial instruments, net of income tax benefit of $5.3 million		(10.0)		(15.7)
Minimum pension liabilities	1.3	0.7	23.0	(0.1)
Comprehensive income (loss)	(58.3)	(2.9)	(3.4)	31.6
Adoption of ASU 2016-16					$ (2.1)
Current period mark to redemption value of redeemable noncontrolling interest	(2.2)	0.8	1.1	1.0
Net income allocated to redeemable noncontrolling interests		(0.5)	(0.1)	(1.3)
Dividends paid to Greif, Inc. shareholders	(26.1)	(26.1)	(52.0)	(51.8)
Dividends paid to noncontrolling interests and other	(7.7)	(7.5)	(8.5)	(7.9)
Restricted stock	1.0			1.1
Long-term incentive shares issued	5.3	1.1	5.3	11.6
Share based compensation	0.5		0.5
Ending balance	$ 1,135.2	1,136.4	1,135.2	1,136.4
Other comprehensive income (loss), derivatives qualifying as hedges, tax		$ 5.3		$ 3.4
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)	48,269	48,241	48,266	47,949
Beginning balance	$ 162.7	$ 161.5	$ 162.6	$ 150.5
Other comprehensive income (loss):
Restricted stock (shares)	28			25
Restricted stock	$ 1.0			$ 1.1
Long-term incentive shares issued (shares)	153	25	153	292
Long-term incentive shares issued	$ 5.0	$ 1.1	$ 5.0	$ 11.0
Share based compensation	$ 0.5		$ 0.5
Ending balance (shares)	48,450	48,266	48,450	48,266
Ending balance	$ 169.2	$ 162.6	$ 169.2	$ 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)	28,573	28,601	28,576	28,893
Beginning balance	$ (134.7)	$ (134.8)	$ (134.8)	$ (135.4)
Other comprehensive income (loss):
Restricted stock (shares)	(28)			(25)
Restricted stock	$ 0.0
Long-term incentive shares issued (shares)	(153)	(25)	(153)	(292)
Long-term incentive shares issued	$ 0.3	$ 0.0	$ 0.3	$ 0.6
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	1,548.7	1,471.9	1,539.0	1,469.8
Net income	11.4	13.6	43.7	43.3
Other comprehensive income (loss):
Adoption of ASU 2016-16					(2.1)
Current period mark to redemption value of redeemable noncontrolling interest	(2.2)	0.8	1.1	1.0
Dividends paid to Greif, Inc. shareholders	(26.1)	(26.1)	(52.0)	(51.8)
Ending balance	1,531.8	1,460.2	1,531.8	1,460.2
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(412.9)	(379.4)	(433.7)	(377.1)
Other comprehensive income (loss):
Foreign currency translation	(48.7)	(12.7)	(49.8)	(8.5)
Derivative financial instruments, net of immaterial income tax expense	(23.1)		(22.9)
Derivative financial instruments, net of income tax benefit of $5.3 million		(10.0)		(15.7)
Minimum pension liabilities	1.3	0.7	23.0	(0.1)
Ending balance	(483.4)	(401.4)	(483.4)	(401.4)
Income tax expense			7.5
Greif, Inc. Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,163.8	1,119.2	1,133.1	1,107.8
Net income	11.4	13.6	43.7	43.3
Other comprehensive income (loss):
Foreign currency translation	(48.7)	(12.7)	(49.8)	(8.5)
Derivative financial instruments, net of immaterial income tax expense	(23.1)		(22.9)
Derivative financial instruments, net of income tax benefit of $5.3 million		(10.0)		(15.7)
Minimum pension liabilities	1.3	0.7	23.0	(0.1)
Comprehensive income (loss)	(59.1)	(8.4)	(6.0)	19.0
Adoption of ASU 2016-16					$ (2.1)
Current period mark to redemption value of redeemable noncontrolling interest	(2.2)	0.8	1.1	1.0
Dividends paid to Greif, Inc. shareholders	(26.1)	(26.1)	(52.0)	(51.8)
Restricted stock	1.0			1.1
Long-term incentive shares issued	5.3	1.1	5.3	11.6
Share based compensation	0.5		0.5
Ending balance	1,083.2	1,086.6	1,083.2	1,086.6
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	58.9	52.3	58.0	46.4
Net income	4.4	7.5	8.2	13.6
Other comprehensive income (loss):
Foreign currency translation	(3.6)	(2.0)	(5.6)	(1.0)
Net income allocated to redeemable noncontrolling interests		(0.5)	(0.1)	(1.3)
Dividends paid to noncontrolling interests and other	(7.7)	(7.5)	(8.5)	(7.9)
Ending balance	$ 52.0	$ 49.8	$ 52.0	$ 49.8
Class A Common Stock
Other comprehensive income (loss):
Dividends (in usd per share)	$ 0.44	$ 0.44	$ 0.88	$ 0.88
Class B Common Stock
Other comprehensive income (loss):
Dividends (in usd per share)	$ 0.66	$ 0.66	$ 1.31	$ 1.31