5. Income Taxes (Details - Deferred Income Tax Assets and Liabilities) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Benefit plans	$ 1,819	$ 1,958
Inventories	519	473
Other	1,292	733
Total deferred tax assets	3,630	3,164
Deferred tax liabilities:
Property, plant and equipment	9,550	9,585
Patents and goodwill	2,833	2,897
Other	0	91
Total deferred tax liabilities	12,383	12,573
Net deferred tax liability	8,753	9,409
Balance Sheet classification:
Non-current deferred income tax liability	9,404	9,989
Current deferred income tax asset	651	580
Net deferred tax liability	$ 8,753	$ 9,409