Note 10 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Note 10 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost [Line Items]
Service cost	$ 184	$ 120	$ 369	$ 242
Interest cost	163	143	325	285
Recognized prior service cost	12	52	25	104
Recognized net actuarial loss (gain)	11	(16)	21	(33)
Net periodic benefit cost	$ 370	$ 299	$ 740	$ 598