Note 8 - Pension - U.S. Pension Plan Assets at Fair Value (Details) - Pension Plan [Member] - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan, Short-term Investments [Member]
Measured at NAV as a practical expedient	$ 7,489,000	$ 9,796,000
Target Allocation 2020	3.00%
Defined Benefit Plan, Real Estate [Member]
Measured at NAV as a practical expedient	$ 7,623,000	6,198,000
Target Allocation 2020	2.00%
Defined Benefit Plan, Equity Securities [Member]
Measured at NAV as a practical expedient	$ 139,060,000	108,952,000
Target Allocation 2020	40.00%
Defined Benefit Plan, Debt Security [Member]
Measured at NAV as a practical expedient	$ 155,574,000	146,080,000
Target Allocation 2020	45.00%
Hedge Funds [Member]
Measured at NAV as a practical expedient	$ 36,554,000	33,058,000
Target Allocation 2020	10.00%
Plan Asset Investments [Member]
Measured at NAV as a practical expedient	$ 346,300	$ 304,084
Target Allocation 2020	100.00%