Note 13 - Employee Benefit Plans - Components of Net Periodic Pension Cost and Assumed Discount Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Service cost	$ 245	$ 231	$ 184
Interest cost	358	372	382
Amortization of prior service cost	228	228	226
Amortization of losses	57	31	47
Net periodic cost	$ 888	$ 862	$ 839
Assumed discount rate	4.28%	3.85%	4.22%