Other current assets - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
Jul. 31, 2017	Jul. 31, 2016
Increase (Decrease) In Other Noncurrent Assets	$ (51)	$ 116
Notes Receivable [Member]
Increase (Decrease) In Other Noncurrent Assets	$ 42

Amount of increase (decrease) in noncurrent assets classified as other.

No definition available.

Name:	us-gaap_IncreaseDecreaseInOtherNoncurrentAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration