Note 14 - Retirement Plans (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan, Expected Amortization, Next Fiscal Year, Total	$ 352
Defined Benefit Plan, Expected Amortization of Gain (Loss), Next Fiscal Year	143
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	11,435
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	67	$ 225
Postretirement Health Coverage [Member]
Defined Benefit Plan, Funded (Unfunded) Status of Plan, Total	(381)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total	26	22
401K [Member]
Defined Contribution Plan, Employer Discretionary Contribution Amount	288	209
Defined Benefit Plan, Plan Assets, Contributions by Employer	81	192
Defined Benefit Plan, Funded (Unfunded) Status of Plan, Total	(3,710)	(3,628)
Defined Benefit Plan, Plan Assets, Amount, Ending Balance	11,448	10,871	$ 12,534
Defined Benefit ACS Retirement Plan [Member]
Defined Benefit Plan, Plan Assets, Contributions by Employer	81	192
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year	889
Defined Benefit ACS Retirement Plan [Member] | Other Noncurrent Liabilities [Member]
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position, Total	$ 3,710	$ 3,628