Note 12 - Retirement Plans - Summary of Net Periodic Pension Expense for ACS Retirement Plan (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Interest cost	$ 141	$ 156	$ 282	$ 312
Expected return on plan assets	(198)	(185)	(396)	(370)
Amortization of loss	148	183	296	366
Net periodic pension expense	$ 91	$ 154	$ 182	$ 308