Note 10 - Pension and Other Postretirement Benefit Plans (Details) - The Components of the Net Pension Expense for the Retirement Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Employee Pension Plan [Member]
Note 10 - Pension and Other Postretirement Benefit Plans (Details) - The Components of the Net Pension Expense for the Retirement Plan [Line Items]
Interest cost	$ 221	$ 223	$ 663	$ 669
Amortization of unrecognized gain (loss)	291	190	872	570
Expected return on plan assets	(350)	(336)	(1,050)	(1,008)
Net pension expense	162	77	485	231
Directors' Plan [Member]
Note 10 - Pension and Other Postretirement Benefit Plans (Details) - The Components of the Net Pension Expense for the Retirement Plan [Line Items]
Service cost	11	13	33	39
Interest cost	24	29	72	87
Amortization of unrecognized gain (loss)	(14)	(15)	(42)	(45)
Amortization of past service liability	10	10	30	30
Net pension expense	31	37	93	111
Other Postretirement Benefit Plan [Member]
Note 10 - Pension and Other Postretirement Benefit Plans (Details) - The Components of the Net Pension Expense for the Retirement Plan [Line Items]
Service cost	95	90	285	270
Interest cost	75	63	225	189
Amortization of unrecognized gain (loss)	30	0	90	0
Amortization of past service liability	(21)	(22)	(64)	(67)
Net pension expense	$ 179	$ 131	$ 536	$ 392