Note 8 - Summary of Options Outstanding and Exercisable (Details)	Mar. 31, 2016 $ / shares shares
Range One [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 2.64
Options Outstanding Number Outstanding (in shares) | shares	12,500
Options Outstanding Weighted Average Remaining Contractual Term	9 years 43 days
Options Exercisable Number Exercisable (in shares) | shares
Options Exercisable Weighted Average Exercise Price (in dollars per share)
Range Two [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 3.75
Options Outstanding Number Outstanding (in shares) | shares	79,376
Options Outstanding Weighted Average Remaining Contractual Term	8 years 313 days
Options Exercisable Number Exercisable (in shares) | shares	21,498
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 3.75
Label 3 (in dollars per share)	3.68
Exercise Price Range - Upper Limit (in dollars per share)	3.76
Range Three [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 4.80
Options Outstanding Number Outstanding (in shares) | shares	212,300
Options Outstanding Weighted Average Remaining Contractual Term	8 years 156 days
Options Exercisable Number Exercisable (in shares) | shares	81,288
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 4.80
Range Four [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 6
Options Outstanding Number Outstanding (in shares) | shares	609,003
Options Outstanding Weighted Average Remaining Contractual Term	9 years 262 days
Options Exercisable Number Exercisable (in shares) | shares	29,599
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 6
Range Five [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 6.35
Options Outstanding Number Outstanding (in shares) | shares	129,267
Options Outstanding Weighted Average Remaining Contractual Term	9 years 332 days
Options Exercisable Number Exercisable (in shares) | shares
Options Exercisable Weighted Average Exercise Price (in dollars per share)
Label 3 (in dollars per share)	$ 6.24
Exercise Price Range - Upper Limit (in dollars per share)	6.40
Range Six [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 7.67
Options Outstanding Number Outstanding (in shares) | shares	41,875
Options Outstanding Weighted Average Remaining Contractual Term	9 years 127 days
Options Exercisable Number Exercisable (in shares) | shares
Options Exercisable Weighted Average Exercise Price (in dollars per share)
Label 3 (in dollars per share)	$ 7.12
Exercise Price Range - Upper Limit (in dollars per share)	7.92
Range Seven [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 9.92
Options Outstanding Number Outstanding (in shares) | shares	38,429
Options Outstanding Weighted Average Remaining Contractual Term	6 years 215 days
Options Exercisable Number Exercisable (in shares) | shares	38,429
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 9.92
Range Eight [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 69.63
Options Outstanding Number Outstanding (in shares) | shares	6,810
Options Outstanding Weighted Average Remaining Contractual Term	1 year 153 days
Options Exercisable Number Exercisable (in shares) | shares	6,810
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 69.63
Label 3 (in dollars per share)	56
Exercise Price Range - Upper Limit (in dollars per share)	72
Range Nine [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 119.53
Options Outstanding Number Outstanding (in shares) | shares	2,176
Options Outstanding Weighted Average Remaining Contractual Term	1 year 178 days
Options Exercisable Number Exercisable (in shares) | shares	2,176
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 119.53
Label 3 (in dollars per share)	96
Exercise Price Range - Upper Limit (in dollars per share)	149.04
Range Ten [Member]
Exercise Price Range - Weighted Average (in dollars per share)	$ 296
Options Outstanding Number Outstanding (in shares) | shares	32
Options Outstanding Weighted Average Remaining Contractual Term	1 year 175 days
Options Exercisable Number Exercisable (in shares) | shares	32
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 296
Exercise Price Range - Weighted Average (in dollars per share)	$ 6.42
Options Outstanding Number Outstanding (in shares) | shares	1,131,768
Options Outstanding Weighted Average Remaining Contractual Term	9 years 87 days
Options Exercisable Number Exercisable (in shares) | shares	179,832
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 9.86