Note 10 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	1 Months Ended
	Mar. 31, 2018	Sep. 30, 2021	Dec. 31, 2020
Long-term Debt, Gross		$ 325,000	$ 383,000
Fair Value, Inputs, Level 2 [Member]
Long-term Debt, Fair Value		321,000	372,000
Interest Rate Swap [Member]
Derivative, Term of Contract (Year)	5 years
Derivative, Notional Amount	$ 250,000
Derivative, Fixed Interest Rate	2.7145%
Derivative, Fair Value, Net, Total	$ 0	(9,000)	(14,000)
Foreign Exchange Contract [Member] | Fair Value, Inputs, Level 2 [Member]
Derivative, Notional Amount		$ 0	$ 3,000