ACQUISITIONS AND DIVESTITURES - Pro forma information of acquiree (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Class of Stock [Line Items]
Pro forma net sales	$ 1,244.8	$ 1,302.2	$ 2,474.0	$ 2,517.2
Pro forma net (loss) income attributable to Greif, Inc.	$ 7.2	$ 39.4	$ 28.0	$ 46.0
Class A Common Stock
Basic earnings per share attributable to Greif, Inc. common shareholders:
Basic (in USD per share)	$ 0.12	$ 0.67	$ 0.48	$ 0.79
Diluted (in USD per share)	0.12	0.67	0.48	0.79
Class B Common Stock
Basic earnings per share attributable to Greif, Inc. common shareholders:
Basic (in USD per share)	0.18	1.00	0.71	1.17
Diluted (in USD per share)	$ 0.18	$ 1.00	$ 0.71	$ 1.17

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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