Note 7 - Common Stock - Summary of Outstanding Warrants (Details) - $ / shares	9 Months Ended
	Sep. 30, 2016	Jun. 20, 2016	May 31, 2016	Apr. 30, 2016
September 2014 Issuance Through Private Offering [Member]
Expiration Date	Sep. 23, 2019
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	91,532
Vendors and Contractor Warrants, October 2014 Issuance [Member]
Expiration Date	Oct. 13, 2019
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	29,000
Vendors and Contractor Warrants, November 2014 Issuance [Member]
Expiration Date	Nov. 12, 2019
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	12,500
Employee Performance Bonus Warrants, February 2015 Issuance [Member]
Expiration Date	Feb. 17, 2025
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	75,697
Contractor Warrants, March 2015 Issuance [Member]
Expiration Date	Mar. 26, 2025
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 2.72
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,454
Contractor Warrants, May 2015 Issuance [Member]
Expiration Date	May 12, 2025
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	36,229
May 2015 Issuance Second Contractor [Member]
Expiration Date	May 17, 2020
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.24
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	21,585
Performance Bonus Warrants, December 2015 Issuance [Member]
Expiration Date	Dec. 16, 2025
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 5.60
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	26,875
Distributor Warrants, March 2016 Issuance [Member]
Expiration Date	Apr. 01, 2026
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 6.08			$ 6.08
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	25,000			25,000
Contractor Warrants, May 2016 Issuance [Member]
Expiration Date	May 11, 2021
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 7.74		$ 7.74
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	5,000		5,000
June 2016 Issuance Related to 2016 Loan Agreement [Member]
Expiration Date	Jun. 20, 2026
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.98	$ 4.98
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	100,402	100,402
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	425,274