Note 10 - Components of Net Expense for Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Employee Pension Plan [Member]
Employee Pension Plan:
Interest cost	$ 226	$ 221	$ 452	$ 442
Amortization of unrecognized (gain) loss	201	290	402	581
Expected return on plan assets	(348)	(350)	(696)	(700)
Net expense	79	161	158	323
DirectorsPlanMember
Employee Pension Plan:
Interest cost	24	24	48	48
Amortization of unrecognized (gain) loss	(21)	(14)	(42)	(28)
Net expense	24	31	48	62
Service cost	11	11	22	22
Amortization of past service liability (credit)	10	10	20	20
Other Postretirement Benefit Plan [Member]
Employee Pension Plan:
Interest cost	80	75	160	150
Amortization of unrecognized (gain) loss	12	30	24	60
Net expense	160	178	321	357
Service cost	90	95	180	190
Amortization of past service liability (credit)	$ (22)	$ (22)	$ (43)	$ (43)