Note 14 - Benefit Plans - Weighted-average Asset Allocation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Asset Category, Target	100.00%
Fair values of the Pension Plan's assets	$ 46,488	$ 43,985	$ 45,452
Asset Category, Percentage	100.00%	100.00%
Fixed Income Funds [Member]
Asset Category, Target	20.00%
Fair values of the Pension Plan's assets	$ 7,812	$ 8,571
Asset Category, Percentage	17.00%	19.00%
Domestic Equity [Member]
Asset Category, Target	49.00%
Fair values of the Pension Plan's assets	$ 19,615	$ 20,479
Asset Category, Percentage	42.00%	47.00%
International Equity [Member]
Asset Category, Target	21.00%
Fair values of the Pension Plan's assets	$ 13,466	$ 9,687
Asset Category, Percentage	29.00%	22.00%
Real Estate [Member]
Asset Category, Target	10.00%
Fair values of the Pension Plan's assets	$ 5,595	$ 5,248
Asset Category, Percentage	12.00%	12.00%