Note 15 - Employee Benefit Plans - Net Periodic Benefit Cost Recognized in Consolidated Statements of Operations (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Selling, general and administrative expenses	$ 5,000	$ 4,000
Net Periodic Defined Benefits Expense (Reversal of Expense), Excluding Service Cost Component	728,000	970,000
Total	733,000	974,000
Selling, General and Administrative Expenses [Member]
Selling, general and administrative expenses	$ 5,000	$ 4,000

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration