Note 7- Embedded Derivatives and Derivative Warrant Liabilities - Schedule of Shares Issued Upon Exercise of Warrants (Details) - $ / shares		6 Months Ended
		Jun. 30, 2018		Feb. 28, 2017	Feb. 17, 2017	Sep. 13, 2016	Apr. 01, 2016	Dec. 11, 2015	May 19, 2015	Feb. 03, 2015	Aug. 05, 2014	Dec. 16, 2013
Shares Underlying Warrants (in shares)		58,902	[1]	855,378
Shares Issues Upon Warrant Exercises (in shares)		755,476
2013 Warrants [Member]
Warrant, Issuance Date		Dec. 16, 2013
Warrants, Expiration date		Dec. 16, 2018
Warrant Exercise Price (in dollars per share)		$ 85.05
Shares Underlying Warrants (in shares)		2,789	[1]									3,551
Shares Issues Upon Warrant Exercises (in shares)		762
2014 Warrants [Member]
Warrant, Issuance Date		Aug. 05, 2014
Warrants, Expiration date		Aug. 05, 2019
Warrant Exercise Price (in dollars per share)		$ 65.50
Shares Underlying Warrants (in shares)		974	[1]								2,500
Shares Issues Upon Warrant Exercises (in shares)		1,526
Series A Warrants [Member]
Warrant, Issuance Date		Feb. 03, 2015
Warrants, Expiration date		Feb. 03, 2020
Warrant Exercise Price (in dollars per share)		$ 3.80
Shares Underlying Warrants (in shares)		320	[1]							5,542
Shares Issues Upon Warrant Exercises (in shares)		5,222
Series B Warrants [Member]
Warrant, Issuance Date		Feb. 03, 2015
Warrants, Expiration date		Aug. 03, 2015
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]							5,542
Shares Issues Upon Warrant Exercises (in shares)		5,542
Series C Warrants [Member]
Warrant, Issuance Date		May 19, 2015
Warrants, Expiration date		May 19, 2020
Warrant Exercise Price (in dollars per share)		$ 53.43
Shares Underlying Warrants (in shares)		1,075	[1]						1,075
Shares Issues Upon Warrant Exercises (in shares)
Series D Warrants [Member]
Warrant, Issuance Date		Dec. 11, 2015
Warrants, Expiration date		Dec. 11, 2020
Warrant Exercise Price (in dollars per share)		$ 40
Shares Underlying Warrants (in shares)		47	[1]					25,125
Shares Issues Upon Warrant Exercises (in shares)		25,078
Series E Warrants [Member]
Warrant, Issuance Date		Dec. 11, 2015
Warrants, Expiration date		Dec. 11, 2020
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]					20,000
Shares Issues Upon Warrant Exercises (in shares)		20,000
Series F Warrants [Member]
Warrant, Issuance Date		Apr. 01, 2016
Warrants, Expiration date		Apr. 01, 2021
Warrant Exercise Price (in dollars per share)		$ 40
Shares Underlying Warrants (in shares)		14,041	[1]				25,733
Shares Issues Upon Warrant Exercises (in shares)		11,692
Series G Warrants [Member]
Warrant, Issuance Date		Apr. 01, 2016
Warrants, Expiration date		Apr. 01, 2017
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]				16,429
Shares Issues Upon Warrant Exercises (in shares)		16,429
Series H Warrants [Member]
Warrant, Issuance Date		Apr. 01, 2016
Warrants, Expiration date		Oct. 01, 2016
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]				51,465
Shares Issues Upon Warrant Exercises (in shares)		51,465
Series I Warrants [Member]
Warrant, Issuance Date		Sep. 13, 2016
Warrants, Expiration date		Sep. 13, 2021
Warrant Exercise Price (in dollars per share)		$ 220
Shares Underlying Warrants (in shares)		35,650	[1]			35,650
Shares Issues Upon Warrant Exercises (in shares)
Series J Warrants [Member]
Warrant, Issuance Date		Sep. 13, 2016
Warrants, Expiration date		Sep. 13, 2017
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]			9,250
Shares Issues Upon Warrant Exercises (in shares)		9,250
Series K Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Feb. 17, 2022
Warrant Exercise Price (in dollars per share)		$ 3.80
Shares Underlying Warrants (in shares)		4,006	[1]		312,516
Shares Issues Upon Warrant Exercises (in shares)		308,510
Series L Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Feb. 17, 2018
Warrant Exercise Price (in dollars per share)	[2]
Shares Underlying Warrants (in shares)			[1]		28,500
Shares Issues Upon Warrant Exercises (in shares)		28,500
Series M-A Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Nov. 17, 2017
Warrant Exercise Price (in dollars per share)	[2],[3]
Shares Underlying Warrants (in shares)			[1]		115,250
Shares Issues Upon Warrant Exercises (in shares)		74,250
Series M-B Warrants [Member]
Warrant, Issuance Date		Feb. 17, 2017
Warrants, Expiration date		Nov. 17, 2017
Warrant Exercise Price (in dollars per share)	[2],[4]
Shares Underlying Warrants (in shares)			[1]		197,250
Shares Issues Upon Warrant Exercises (in shares)		197,250

[1] This table does not include equity-classified warrants to purchase 6 shares of common stock issued in 2011, with strike price of $354 per share.

[2] Warrants have either been fully exercised and/or expired as of June 30, 2018.

[3] In October 2017, the exercise price of Series M warrants to purchase 74,250 shares of common stock were repriced between $12.00 and $13.00 per share. Of those warrants that were repriced, all were exercised in the fourth quarter of 2017, providing proceeds of $1.0 million.

[4] In September 2017, the exercise price of Series M warrants to purchase 197,250 shares of common stock were repriced to $0.60 per share. Of those warrants that were repriced, all were exercised in the second half of 2017, providing proceeds of $2.4 million.