Note 1 - Summary of Significant Accounting Policies - Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Total carrying amount of long-term debt	$ 24,493	$ 26,620
Estimated fair value of long-term debt	24,364	27,708
Fair Value, Recurring [Member]
Assets, fair value	2,507	6,306
Money Market Funds [Member] \| Fair Value, Recurring [Member]
Assets, fair value	2,507	6,306
Fair Value, Inputs, Level 1 [Member] \| Fair Value, Recurring [Member]
Assets, fair value	2,507	6,306
Fair Value, Inputs, Level 1 [Member] \| Money Market Funds [Member] \| Fair Value, Recurring [Member]
Assets, fair value	$ 2,507	$ 6,306

Amount, excluding unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant