ACQUISITIONS AND DIVESTITURES - Pro forma information of acquiree (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Class of Stock [Line Items]
Pro forma net sales	$ 1,252.6	$ 1,367.3	$ 3,726.6	$ 3,897.9
Pro forma net (loss) income attributable to Greif, Inc.	$ 62.7	$ 70.2	$ 90.8	$ 114.8
Class A Common Stock
Basic earnings per share attributable to Greif, Inc. common shareholders:
Basic (in USD per share)	$ 1.06	$ 1.19	$ 1.54	$ 1.95
Diluted (in USD per share)	1.06	1.19	1.54	1.95
Class B Common Stock
Basic earnings per share attributable to Greif, Inc. common shareholders:
Basic (in USD per share)	1.59	1.79	2.30	2.92
Diluted (in USD per share)	$ 1.59	$ 1.79	$ 2.30	$ 2.92