Note 8 - Share-based Compensation - Exercise Price Range Relating to Outstanding and Exercisable Options (Details)	3 Months Ended
	Sep. 30, 2016 $ / shares shares
Range One [Member]
Exercise price range, lower limit (in dollars per share)	$ 1.30
Exercise price range, upper limit (in dollars per share)	$ 1.40
Outstanding Weighted Average Number of Stock Options (in shares) | shares	1,514,167
Outstanding Weighted Average Remaining Contractual Life	9 years 299 days
Weighted Average Exercise Price (in dollars per share)	$ 1.34
Exercisable Number of Stock Options (in shares) | shares	9,167
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.37
Range Two [Member]
Exercise price range, lower limit (in dollars per share)	1.50
Exercise price range, upper limit (in dollars per share)	$ 2.45
Outstanding Weighted Average Number of Stock Options (in shares) | shares	1,617,547
Outstanding Weighted Average Remaining Contractual Life	8 years 7 days
Weighted Average Exercise Price (in dollars per share)	$ 2.26
Exercisable Number of Stock Options (in shares) | shares	491,460
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 2.37
Range Three [Member]
Exercise price range, lower limit (in dollars per share)	2.47
Exercise price range, upper limit (in dollars per share)	$ 4.07
Outstanding Weighted Average Number of Stock Options (in shares) | shares	2,274,000
Outstanding Weighted Average Remaining Contractual Life	5 years 288 days
Weighted Average Exercise Price (in dollars per share)	$ 3.29
Exercisable Number of Stock Options (in shares) | shares	1,587,290
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 3.61
Range Four [Member]
Exercise price range, lower limit (in dollars per share)	4.15
Exercise price range, upper limit (in dollars per share)	$ 39.60
Outstanding Weighted Average Number of Stock Options (in shares) | shares	401,186
Outstanding Weighted Average Remaining Contractual Life	4 years 324 days
Weighted Average Exercise Price (in dollars per share)	$ 18.08
Exercisable Number of Stock Options (in shares) | shares	308,686
Exercisable Weighted Average Exercise Price (in dollars per share)	$ 22.02