Note 12 - Retirement Plans - Summary of Net Periodic Pension Expense for ACS Retirement Plan (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest cost	$ 143	$ 153	$ 425	$ 465
Expected return on plan assets	(198)	(184)	(594)	(554)
Amortization of loss	42	184	338	550
Net periodic pension expense	$ (13)	$ 153	$ 169	$ 461