Note 13 - Retirement Plans - Summary of Net Periodic Pension Expense for ACS Retirement Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Interest cost	$ 566	$ 620
Expected return on plan assets	(792)	(1,024)
Amortization of loss	451	1,019
Net periodic pension expense	$ 225	$ 615