Note 8 - Income Taxes - Summary of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Net operating loss and tax credit carryforwards	$ 38,915	$ 47,640
Joint venture and other investments	18	183
Accrued retirement benefits	3,924	3,608
Property net book value	2,801	3,275
Deferred revenue	953	1,101
Stock compensation	22	22
Reserves and other	404	408
Total deferred tax assets	47,037	56,237
Valuation allowance	(47,037)	(56,237)
Net deferred tax assets