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, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018	Oct. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,171.5	$ 1,126.5	$ 1,154.2	$ 1,047.5
Net income	21.1	51.9	56.9	112.0
Other comprehensive income (loss):
Foreign currency translation	(14.7)	(26.3)	(9.5)	12.1
Derivative financial instruments	(10.0)	1.4	(15.7)	5.3
Minimum pension liability adjustment, net of immaterial income tax	0.7	2.7	(0.1)	1.8
Comprehensive income (loss)	(2.9)	29.7	31.6	131.2
Adoption of ASU 2016-16					$ (2.1)
Current period mark to redemption value of redeemable noncontrolling interest	0.8	(0.4)	1.0	(1.8)
Net income allocated to redeemable noncontrolling interests	(0.5)	(0.8)	(1.3)	(1.9)
Dividends paid to Greif, Inc. shareholders	(26.1)	(24.8)	(51.8)	(49.3)
Dividends paid to noncontrolling interests and other	(7.5)	(2.2)	(7.9)	(2.7)
Restricted stock directors	(1.1)	(1.0)	(1.1)	(1.0)
Long-term incentive shares issued		0.3	11.6	5.3
Ending balance	1,136.4	1,129.3	1,136.4	1,129.3
Other comprehensive income (loss), derivatives qualifying as hedges, tax	$ 5.3	$ 0.3	$ 3.4	$ 1.8
Capital Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (shares)	48,241	47,925	47,949	47,843
Beginning balance	$ 161.5	$ 149.1	$ 150.5	$ 144.2
Other comprehensive income (loss):
Restricted stock directors (in shares)	25	21	25	21
Restricted stock directors	$ (1.1)	$ (1.0)	$ (1.1)	$ (1.0)
Long-term incentive shares issued (shares)		3	292	85
Long-term incentive shares issued		$ 0.2	$ 11.0	$ 5.1
Ending balance	$ 162.6	$ 150.3	$ 162.6	$ 150.3
Ending balance (shares)	48,266	47,949	48,266	47,949
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (shares)	28,601	28,917	28,893	28,999
Beginning balance	$ (134.8)	$ (135.5)	$ (135.4)	$ (135.6)
Other comprehensive income (loss):
Restricted stock directors (in shares)	(25)	(21)	(25)	(21)
Restricted stock directors				$ 0.0
Long-term incentive shares issued (shares)		(3)	(292)	(85)
Long-term incentive shares issued		$ 0.1	$ 0.6	$ 0.2
Ending balance	$ (134.8)	$ (135.4)	$ (134.8)	$ (135.4)
Ending balance (shares)	28,576	28,893	28,576	28,893
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 1,471.9	$ 1,390.5	$ 1,469.8	$ 1,360.5
Net income	13.6	45.1	43.3	101.6
Other comprehensive income (loss):
Derivative financial instruments				(0.6)
Adoption of ASU 2016-16					(2.1)
Current period mark to redemption value of redeemable noncontrolling interest	0.8	(0.4)	1.0	(1.8)
Dividends paid to Greif, Inc. shareholders	(26.1)	(24.8)	(51.8)	(49.3)
Ending balance	1,460.2	1,410.4	1,460.2	1,410.4
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(379.4)	(316.6)	(377.1)	(358.2)
Other comprehensive income (loss):
Foreign currency translation	(12.7)	(26.3)	(8.5)	11.7
Derivative financial instruments	(10.0)	1.4	(15.7)	5.9
Minimum pension liability adjustment, net of immaterial income tax	0.7	2.7	(0.1)	1.8
Ending balance	(401.4)	(338.8)	(401.4)	(338.8)
Greif, Inc. Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,119.2	1,087.5	1,107.8	1,010.9
Net income	13.6	45.1	43.3	101.6
Other comprehensive income (loss):
Foreign currency translation	(12.7)	(26.3)	(8.5)	11.7
Derivative financial instruments	(10.0)	1.4	(15.7)	5.3
Minimum pension liability adjustment, net of immaterial income tax	0.7	2.7	(0.1)	1.8
Comprehensive income (loss)	(8.4)	22.9	19.0	120.4
Adoption of ASU 2016-16					$ (2.1)
Current period mark to redemption value of redeemable noncontrolling interest	0.8	(0.4)	1.0	(1.8)
Dividends paid to Greif, Inc. shareholders	(26.1)	(24.8)	(51.8)	(49.3)
Restricted stock directors	(1.1)	(1.0)	(1.1)	(1.0)
Long-term incentive shares issued		0.3	11.6	5.3
Ending balance	1,086.6	1,086.5	1,086.6	1,086.5
Non controlling interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	52.3	39.0	46.4	36.6
Net income	7.5	6.8	13.6	10.4
Other comprehensive income (loss):
Foreign currency translation	(2.0)	0.0	(1.0)	0.4
Net income allocated to redeemable noncontrolling interests	(0.5)	(0.8)	(1.3)	(1.9)
Dividends paid to noncontrolling interests and other	(7.5)	(2.2)	(7.9)	(2.7)
Ending balance	$ 49.8	$ 42.8	$ 49.8	$ 42.8
Class A Common Stock
Other comprehensive income (loss):
Dividends (in usd per share)	$ 0.44	$ 0.42	$ 0.88	$ 0.84
Class B Common Stock
Other comprehensive income (loss):
Dividends (in usd per share)	$ 0.66	$ 0.63	$ 1.31	$ 1.25