Note 1 - Significant Accounting Policies (Details Textual) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) shares	Sep. 30, 2017 USD ($) shares	Sep. 30, 2018 USD ($) shares	Sep. 30, 2017 USD ($) shares	Jul. 20, 2018 USD ($)	Jul. 10, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 23, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 09, 2011 USD ($)
Business Combination, Agreement Terminated, Expected Transaction-related Expenses						$ 6,000
Long-term Line of Credit, Total	$ 28,293		$ 28,293				$ 16,750
Restricted Cash and Cash Equivalents, Current, Total	1,506		1,506				3,286
Loss on Sale of Investments			0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax			1	$ 0
Interest Expense, Debt, Total	2,346	$ 2,140	6,762	6,334
Amortization of Debt Issuance Costs	222	219	676	658
Interest Expense, Total	2,346	$ 2,140	6,762	$ 6,334
Lease Financing Obligation, Net of Current	$ 2,704		$ 2,704				2,751
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount | shares	2,475	1,996	2,071	2,519
RAPIVAB [Member] | Customer Concentration Risk [Member] | Sales Revenue, Product Line [Member]
Number of Major Customers			3
RAPIVAB [Member] | Customer Concentration Risk [Member] | Sales Revenue, Product Line [Member] | Three Customers [Member]
Concentration Risk, Percentage			90.00%
Foreign Exchange Contract [Member] | Not Designated as Hedging Instrument [Member]
Derivative, Loss on Derivative			$ 606	$ 1,858
Derivative, Gain on Derivative			940	966
Currency Hedge Agreement [Member]
Collateral Already Posted, Aggregate Fair Value	$ 0		0				0
Birmingham Research Facility [Member]
Interest Expense, Total	85	$ 82	252	$ 217
Lease Financing Obligation, Net of Current	2,703		2,703				$ 2,703
Capital Leases, Future Minimum Payments Due, Total	4,002		$ 4,002
Computer Equipment [Member]
Property, Plant and Equipment, Useful Life			3 years
Laboratory Equipment, Office Equipment and Software [Member]
Property, Plant and Equipment, Useful Life			5 years
Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life			7 years
Leasehold Improvements [Member] | Birmingham Research Facility [Member]
Property, Plant and Equipment, Useful Life			20 years 182 days
Property, Plant and Equipment, Gross, Ending Balance									$ 1,589
Maximum [Member]
Maturity Period of High Quality Marketable Securities			3 years
Average Maturity Period of High Quality Marketable Securities			1 year 180 days
Maturity Period of Short Term Investment			1 year
Average Maturity for Portfolio Investments			1 year 180 days
Minimum [Member]
Maturity Period of Short Term Investment			90 days
Long-term Investment Maturity, Minimum			1 year
Collateral for Credit [Member]
Restricted Cash and Cash Equivalents, Current, Total	1,413		$ 1,413
Senior Credit Facility [Member] | MidCap Financial Services, LLC [Member]
Long-term Line of Credit, Total	$ 30,000		$ 30,000		$ 30,000			$ 23,000
JPR Royalty Sub LLC [Member]
Revenue Recognition Royalty and Milestone Revenue Recognized										$ 30,000