Note 8 - Commitments and Contingencies - Supplemental Balance Sheet Information Related to Leases (Details) $ in Thousands	Mar. 31, 2019 USD ($)
Operating lease right-of-use assets	$ 1,730
Present value of lease liabilities	2,182
Prepaid Expenses and Other Current Assets [Member]
Operating lease right-of-use assets	445
Other Noncurrent Assets [Member]
Operating lease right-of-use assets	1,285
Accounts Payable and Accrued Liabilities [Member]
Present value of lease liabilities	565
Other Noncurrent Liabilities [Member]
Present value of lease liabilities	$ 1,617