Note 10 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Note 10 - Postretirement Medical Benefits (Details) - Net Periodic Benefit Cost [Line Items]
Service cost	$ 185	$ 121	$ 554	$ 362
Interest cost	162	142	487	427
Recognized prior service cost	13	51	38	155
Recognized net actuarial loss (gain)	10	(15)	31	(47)
Net periodic benefit cost	$ 370	$ 299	$ 1,110	$ 897