Note 8 - Accrued Retirement Benefits - Accrued Retirement Benefits (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Defined benefit pension plan	$ 10,256	$ 11,091
Less current portion	(165)	(165)
Non-current portion of accrued retirement benefits	10,091	10,926
Pension Plan [Member] \| Qualified Plan [Member]
Defined benefit pension plan	7,987	8,790
Supplemental Employee Retirement Plan [Member] \| Nonqualified Plan [Member]
Defined benefit pension plan	$ 2,269	$ 2,301

Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as noncurrent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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