Note 6 - Lease Obligations and Other Contingencies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Retained Earnings (Accumulated Deficit), Ending Balance	$ (1,023,442)	$ (840,628)
Operating Lease, Weighted Average Remaining Lease Term (Year)	13 years 1 month 6 days
Operating Lease, Weighted Average Discount Rate, Percent	12.70%
Operating Lease, Expense	$ 1,754	1,464
Operating Lease, Payments	1,696	1,457
Operating Lease, Right-of-Use Asset, Accumulated Amortization	2,641	1,386
Accrued Liabilities, Current [Member]
Operating Lease, Liability, Current	1,179	1,377
Other Noncurrent Liabilities [Member]
Operating Lease, Liability, Noncurrent	3,871	3,406
Other Noncurrent Assets [Member]
Operating Lease, Right-of-Use Asset	$ 3,802	$ 3,590
Minimum [Member]
Lessee, Operating Lease, Term of Contract (Year)		1 year
Maximum [Member]
Lessee, Operating Lease, Term of Contract (Year)		5 years
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset			$ 3,621
Operating Lease, Liability, Total			4,822
Accounting Standards Update 2016-02 [Member] | Cumulative Effect, Period of Adoption, Adjustment [Member]
Retained Earnings (Accumulated Deficit), Ending Balance			$ 238