Note 3 - Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Deferred compensation plan	$ 6,202	$ 6,209
Derivatives, assets	26	58
Total assets	6,228	6,267
Derivatives, liabilities	(14)	(8)
Fair Value, Inputs, Level 1 [Member]
Deferred compensation plan	5,317	5,215
Derivatives, assets
Total assets	5,317	5,215
Derivatives, liabilities
Fair Value, Inputs, Level 2 [Member]
Deferred compensation plan	885	994
Derivatives, assets	26	58
Total assets	911	1,052
Derivatives, liabilities	(14)	(8)
Fair Value, Inputs, Level 3 [Member]
Deferred compensation plan
Derivatives, assets
Total assets
Derivatives, liabilities