Note 8 - Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Net operating loss and tax credit carryforwards	$ 46,395	$ 50,361
Joint venture and other investments	183	238
Accrued retirement benefits	4,765	2,550
Property net book value	3,275	2,715
Deferred revenue	1,101	1,160
Stock compensation	22	154
Reserves and other	460	447
Total deferred tax assets	56,201	57,625
Valuation allowance	$ (56,201)	$ (57,625)
Net deferred tax assets