Note 15 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Expense	$ 817	$ 863
Deferred tax benefit	(172)	(181)
Total net expense	645	682
Stock Appreciation Rights (SARs) [Member]
Expense	90	84
Deferred tax benefit	(19)	(18)
Total net expense	71	66
Restricted Stock [Member]
Expense	325	293
Deferred tax benefit	(68)	(61)
Total net expense	257	232
Restricted Stock Units (RSUs) [Member]
Expense	67	81
Deferred tax benefit	(14)	(17)
Total net expense	53	64
Performance Shares [Member]
Expense	335	405
Deferred tax benefit	(71)	(85)
Total net expense	$ 264	$ 320