Note 8 - Debt - Information Pertaining to 2020 Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total	$ 2,858
Embedded Derivative, 2020 Convertible Notes [Member]
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total	(2,858)
Balance - March 31, 2018	2,366
Balance - December 31, 2017	5,224
Convertible 2020 Notes [Member]
Amortization of debt discount	252
Paid-in-kind interest	83
Amortization of debt issue costs	67
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total
Balance - March 31, 2018	13,893
Balance - December 31, 2017	13,491
Balance - March 31, 2018	2,400
Balance - December 31, 2017	5,200
Convertible 2020 Notes [Member] | Embedded Derivative, 2020 Convertible Notes [Member]
Amortization of debt discount	252
Paid-in-kind interest	83
Amortization of debt issue costs	67
Embedded Derivative, Gain (Loss) on Embedded Derivative, Net, Total	(2,858)
Balance - March 31, 2018	16,259
Balance - December 31, 2017	18,715
Convertible 2020 Notes [Member] | Principal Amount of 2020 Notes [Member]
Balance - December 31, 2017	16,657
Paid-in-kind interest	83
Balance – March 31, 2018	16,740
Convertible 2020 Notes [Member] | Debt Issue Costs [Member]
Amortization of debt discount	252
Balance - March 31, 2018	(2,249)
Balance - December 31, 2017	(2,501)
Convertible 2020 Notes [Member] | Debt Discount [Member]
Amortization of debt issue costs	67
Balance - March 31, 2018	(598)
Balance - December 31, 2017	(665)
Convertible 2022 Notes [Member]
Balance - December 31, 2017	0
Convertible 2022 Notes [Member] | Principal Amount of 2022 Notes [Member]
Balance - December 31, 2017	515
Exchange of 2022 Notes	(515)
Balance – March 31, 2018