Intangible assets (Parenthetical) (Detail)	3 Months Ended
	Jan. 31, 2020
Non-compete agreement (estimated life 5 years)
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Customer relationships (estimated lives 7 - 15 years) | Minimum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Customer relationships (estimated lives 7 - 15 years) | Maximum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years
Backlog (estimated life 1 - 2 years) | Minimum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Backlog (estimated life 1 - 2 years) | Maximum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	2 years
Patents (estimated life 10 - 14 years) | Minimum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Patents (estimated life 10 - 14 years) | Maximum
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	14 years