Concentrations of credit risk - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Jan. 31, 2019	Jan. 31, 2018
Concentration Risk [Line Items]
Cash, FDIC insured amount	$ 11.8
Sales Revenue, Goods, Net \| Distributor [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	38.00%	47.00%
Sales Revenue, Goods, Net \| Equipment Manufacturer [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	14.00%
Accounts Receivable \| Distributor [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	30.00%	44.00%
Accounts Receivable \| Equipment Manufacturer [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	22.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109250915&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration