Intangible assets (Parenthetical) (Detail)	3 Months Ended
	Jan. 31, 2018
Customer relationships (estimated lives 7 - 15 years) | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Customer relationships (estimated lives 7 - 15 years) | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Patents (estimated life 14 years)
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	14 years