Summary of status of options granted under stock option plans and changes in options outstanding (Detail) - Stock Option	9 Months Ended
	Jul. 31, 2017 $ / shares shares
Shares
Options Outstanding at November 1, 2016 | shares	1,007,851
Options granted | shares	434,068
Options exercised | shares	(16,763)
Options canceled or expired | shares	(170,653)
Options outstanding at July 31, 2017 | shares	1,254,503
Options exercisable at July 31, 2017 | shares	900,419
Options vested and expected to vest at July 31, 2017 | shares	1,253,107
Weighted Average Exercise Price
Options Outstanding at November 1, 2016 | $ / shares	$ 4.07
Options granted | $ / shares	1.6
Options exercised | $ / shares	1.50
Options canceled or expired | $ / shares	3.84
Options outstanding at July 31, 2017 | $ / shares	3.28
Options exercisable at July 31, 2017 | $ / shares	3.33
Options vested and expected to vest at July 31, 2017 | $ / shares	$ 3.28