Earnings Per Share - Computation of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Numerator for basic and diluted EPS
Net income attributable to Greif, Inc.	$ 45.1	$ 36.0	$ 101.6	$ 41.4
Cash dividends	(24.8)	(24.7)	(49.3)	(49.2)
Undistributed net income (loss) attributable to Greif, Inc.	$ 20.3	$ 11.3	$ 52.3	$ (7.8)