Note 15 - Stock Plans - Stock Options Outstanding and Exercisable (Details)	12 Months Ended
	Oct. 31, 2018 $ / shares shares
Lower limit exercise price (in dollars per share)	$ 1.54
Upper limit exercise price (in dollars per share)	$ 6.28
Number outstanding (in shares) | shares	6,964,326
Weighted-average exercise price - outstanding (in dollars per share)	$ 2.95
Weighted-average remaining contractual life - outstanding (Year)	4 years 160 days
Number exercisable (in shares) | shares	4,793,490
Weighted-average exercise price - exercisable (in dollars per share)	$ 3.29
Weighted-average remaining contractual life - exercisable (Year)	2 years 222 days
Range One [Member]
Lower limit exercise price (in dollars per share)	$ 1.54
Upper limit exercise price (in dollars per share)	$ 2.41
Number outstanding (in shares) | shares	2,645,784
Weighted-average exercise price - outstanding (in dollars per share)	$ 2
Weighted-average remaining contractual life - outstanding (Year)	6 years 116 days
Number exercisable (in shares) | shares	1,108,534
Weighted-average exercise price - exercisable (in dollars per share)	$ 1.97
Weighted-average remaining contractual life - exercisable (Year)	3 years 237 days
Range Two [Member]
Lower limit exercise price (in dollars per share)	$ 2.42
Upper limit exercise price (in dollars per share)	$ 4.41
Number outstanding (in shares) | shares	3,004,042
Weighted-average exercise price - outstanding (in dollars per share)	$ 2.77
Weighted-average remaining contractual life - outstanding (Year)	3 years 208 days
Number exercisable (in shares) | shares	2,370,456
Weighted-average exercise price - exercisable (in dollars per share)	$ 2.81
Weighted-average remaining contractual life - exercisable (Year)	2 years 32 days
Range Three [Member]
Lower limit exercise price (in dollars per share)	$ 4.42
Upper limit exercise price (in dollars per share)	$ 6.28
Number outstanding (in shares) | shares	1,314,500
Weighted-average exercise price - outstanding (in dollars per share)	$ 5.27
Weighted-average remaining contractual life - outstanding (Year)	2 years 240 days
Number exercisable (in shares) | shares	1,314,500
Weighted-average exercise price - exercisable (in dollars per share)	$ 5.27
Weighted-average remaining contractual life - exercisable (Year)	2 years 240 days