Note 4 - Stockholder's Equity (Deficiency) - Options Outstanding Separated into Range of Exercise Price (Details) - $ / shares	6 Months Ended
	Jun. 30, 2015
Range One [Member]
Range of exercise price, minimum (in dollars per share)	$ 0.07
Range of exercise price, maximum (in dollars per share)	$ 0.901
Options outstanding (in shares)	467,436
Outstanding weighted average remaining contractual life	2 years 154 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 0.883
Options exercisable (in shares)	467,436
Exercisable weighted average remaining contractual life	2 years 154 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 0.883
Range Two [Member]
Range of exercise price, minimum (in dollars per share)	1.039
Range of exercise price, maximum (in dollars per share)	$ 1.576
Options outstanding (in shares)	1,630,672
Outstanding weighted average remaining contractual life	3 years 283 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 1.263
Options exercisable (in shares)	1,630,672
Exercisable weighted average remaining contractual life	3 years 283 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 1.263
Range Three [Member]
Range of exercise price, minimum (in dollars per share)	6.23
Range of exercise price, maximum (in dollars per share)	$ 8.80
Options outstanding (in shares)	149,818
Outstanding weighted average remaining contractual life	6 years 151 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 6.772
Options exercisable (in shares)	128,372
Exercisable weighted average remaining contractual life	6 years 130 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 6.777
Range Four [Member]
Options outstanding (in shares)	382,669
Outstanding weighted average remaining contractual life	7 years 247 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 12.47
Options exercisable (in shares)	209,815
Exercisable weighted average remaining contractual life	7 years 239 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 12.47
Range Five [Member]
Options outstanding (in shares)	30,000
Outstanding weighted average remaining contractual life	9 years 317 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 19.51
Range Six [Member]
Range of exercise price, minimum (in dollars per share)	21
Range of exercise price, maximum (in dollars per share)	$ 24.23
Options outstanding (in shares)	969,834
Outstanding weighted average remaining contractual life	8 years 360 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 21.609
Options exercisable (in shares)	154,477
Exercisable weighted average remaining contractual life	8 years 231 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 21.873
Range Seven [Member]
Options outstanding (in shares)	154,200
Outstanding weighted average remaining contractual life	9 years 237 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 29.88
Range Eight [Member]
Options outstanding (in shares)	183,609
Outstanding weighted average remaining contractual life	8 years 267 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 39.86
Options exercisable (in shares)	59,205
Exercisable weighted average remaining contractual life	8 years 267 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 39.86
Options outstanding (in shares)	3,968,238
Outstanding weighted average remaining contractual life	5 years 317 days
Weighted average exercise price of options outstanding (in dollars per share)	$ 10.515
Options exercisable (in shares)	2,649,977
Exercisable weighted average remaining contractual life	4 years 132 days
Weighted average exercise price of options exercisable (in dollars per share)	$ 4.414