Note 12 - Long-Term Debt Interest Expense Recognized Related to Convertible Debt (Details) - Convertible Debt [Member] - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Convertible Senior Notes Due 2017 [Member]
Debt Instrument [Line Items]
Contractual interest expense of convertible debt	[1]	$ 310	$ 872
Amortization of debt discount		619	1,674
Amortization of debt issuance costs		33	88
Total interest expense for convertible debt	[1]	962	2,634
Convertible Senior Notes Due 2019 [Member]
Debt Instrument [Line Items]
Contractual interest expense of convertible debt	[1]	(510)	3,426
Amortization of debt discount		163	5,016
Amortization of debt issuance costs		16	505
Total interest expense for convertible debt	[1]	$ (331)	$ 8,947

[1] Interest expense (benefit) represents expense incurred, net of adjustments to accruals previously recorded.