Intangible assets (Parenthetical) (Detail)	3 Months Ended
	Jan. 31, 2017
Non-compete agreements (estimated lives 3 - 5 years) | Maximum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	5 years
Non-compete agreements (estimated lives 3 - 5 years) | Minimum [Member]
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	3 years
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
Backlog (estimated life 1 year)
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	1 year
Patents (estimated life 14 years)
Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	14 years