Note 12 - Pension and Other Postretirement Benefit Plans - Amounts in Accumulated Other Comprehensive Income to be Recognized as Components of Net Periodic Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Net Actuarial loss (gain)	$ 605
Prior Service cost (credit)	(45)
Total	560
Retirement Plan [Member]
Net Actuarial loss (gain)	697
Prior Service cost (credit)	0
Total	697
Other Postretirement Benefit Plan [Member]
Net Actuarial loss (gain)	0
Prior Service cost (credit)	(85)
Total	(85)
Directors' Plan [Member]
Net Actuarial loss (gain)	(92)
Prior Service cost (credit)	40
Total	$ (52)