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Business activities and summary of significant accounting policies - Intangible assets (Parenthetical) (Detail)
12 Months Ended
Oct. 31, 2019
Oct. 31, 2018
Customer relationships (estimated lives 7 - 15 years) | Maximum [Member]    
Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 15 years 15 years
Customer relationships (estimated lives 7 - 15 years) | Minimum [Member]    
Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 7 years 7 years
Patents (estimated life 14 years)    
Intangible Assets [Line Items]    
Finite-Lived Intangible Asset, Useful Life 14 years 14 years