Note 7 - Income Tax Expense - Deferred Income Tax Asset (Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Pension accruals	$ 3,742	$ 2,588
Operating reserves and other accruals	5,110	2,540
Tax credits	513	923
Valuation allowance on tax credits	0	(923)
Book carrying value in excess of tax basis of property	(2,116)	(1,544)
Book carrying value in excess of tax basis of intangibles	(5,780)	(7,024)
Tax effect of revenue recognition standard ASC 606	(1,021)	(1,771)
Deferred expenses	(898)	(1,831)
Net deferred income tax liability	$ (450)	$ (7,042)