Discontinued operations - Continuing operations and reported as discontinued operations (Details) - USD ($)	12 Months Ended
Oct. 31, 2019	Oct. 31, 2018
Major line items constituting pretax income from discontinued operations:
Pretax income from discontinued operations		$ 221,000
Provision for income taxes	$ 0	41,000
Comnet Telecom Division [Member]
Major line items constituting pretax income from discontinued operations:
Net sales		8,343,000
Cost of sales		(6,199,000)
Gross profit		2,144,000
Selling, general and administrative expenses		(1,569,000)
Pretax income from discontinued operations		575,000
Pretax loss on sale of Comnet		(796,000)
Pretax income from discontinued operations		(221,000)
Provision for income taxes		(41,000)
Income from discontinued operations		$ (180,000)

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Amount of loss on sale of comnet before income tax

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Amount before tax of an increase (decrease) to a gain (loss) previously reported in discontinued operations in a prior period.

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Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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