Note 13 - Postretirement Medical Benefits (Details) - Incremental Effects from a One Percent Change in Assumed Health Care Cost - Postretirement Medical Benefits [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Note 13 - Postretirement Medical Benefits (Details) - Incremental Effects from a One Percent Change in Assumed Health Care Cost [Line Items]
Effect on total of service and interest cost components of net periodic postretirement health care benefit cost	$ 358
Effect on total of service and interest cost components of net periodic postretirement health care benefit cost	(265)
Effect on accumulated postretirement benefit obligation	3,601
Effect on accumulated postretirement benefit obligation	$ (2,764)