Earnings Per Share - Computation of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2015
Numerator for basic and diluted EPS
Net income attributable to Greif	$ 33.3	$ 43.9	$ 36.0	$ 5.4	$ 8.5	$ 46.1	$ 31.4	$ (11.1)	$ 118.6	$ 74.9	$ 71.9
Cash dividends									98.6	98.7	98.7
Undistributed net loss attributable to Greif, Inc.									$ 20.0	$ (23.8)	$ (26.8)
Class A Common Stock
Denominator for basic EPS
Denominator for basic EPS (shares)	25,835,281	25,834,636	25,824,194	25,787,769	25,781,791	25,781,146	25,761,733	25,697,512	25,820,470	25,755,545	25,668,204
Denominator for diluted EPS
Denominator for diluted EPS (shares)	25,835,281	25,835,294	25,828,882	25,792,441	25,785,266	25,783,184	25,766,609	25,704,023	25,822,940	25,756,893	25,674,105
EPS Basic
EPS Basic (usd per share)	$ 0.57	$ 0.74	$ 0.61	$ 0.10	$ 0.14	$ 0.78	$ 0.53	$ (0.19)	$ 2.02	$ 1.28	$ 1.23
EPS Diluted
EPS Diluted (usd per share)	$ 0.57	$ 0.74	$ 0.61	$ 0.10	$ 0.14	$ 0.78	$ 0.53	$ (0.19)	$ 2.02	$ 1.28	$ 1.23
Class B Common Stock
Denominator for basic EPS
Denominator for basic EPS (shares)	22,007,725	22,009,596	22,009,725	22,009,725	22,009,725	22,009,725	22,108,942	22,119,966	22,000,000	22,100,000	22,100,000
Denominator for diluted EPS
Denominator for diluted EPS (shares)	22,007,725	22,009,596	22,009,725	22,009,725	22,009,725	22,009,725	22,108,942	22,119,966	22,000,000	22,100,000	22,100,000
EPS Basic
EPS Basic (usd per share)	$ 0.85	$ 1.12	$ 0.92	$ 0.13	$ 0.22	$ 1.18	$ 0.80	$ (0.29)	$ 3.02	$ 1.90	$ 1.83
EPS Diluted
EPS Diluted (usd per share)	$ 0.85	$ 1.12	$ 0.92	$ 0.13	$ 0.22	$ 1.18	$ 0.80	$ (0.29)	$ 3.02	$ 1.90	$ 1.83