Note 14 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Expense	$ 863	$ 823
Deferred tax benefit	(181)	(173)
Total net expense	682	650
Stock Appreciation Rights (SARs) [Member]
Expense	84	73
Deferred tax benefit	(18)	(15)
Total net expense	66	58
Restricted Stock [Member]
Expense	293	276
Deferred tax benefit	(61)	(58)
Total net expense	232	218
Restricted Stock Units (RSUs) [Member]
Expense	81	63
Deferred tax benefit	(17)	(13)
Total net expense	64	50
Performance Shares [Member]
Expense	405	411
Deferred tax benefit	(85)	(87)
Total net expense	$ 320	$ 324