Note 13 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Note 13 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost [Line Items]
Service cost	$ 739	$ 482
Interest cost	649	569
Recognized prior service cost	51	207
Amortization of net actuarial loss (gain)	42	(63)
Net periodic benefit cost	$ 1,481	$ 1,195
Major assumptions:
Discount rate used to determine net periodic benefit cost	3.92%	4.93%
Discount rate used to determine benefit obligation as of year end	4.34%	3.92%
Retiree participation rate (Plan 1)	100.00%	100.00%
Retiree participation rate (Plan 2)	72.00%	72.00%