Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
OTHER PHYSICAL PROPERTY:
Other physical property, accumulated depreciation	$ 341	$ 329
CURRENT ASSETS:
Receivables, reserves	$ 334	$ 315
COMMON STOCKHOLDERS' EQUITY:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, authorized (in shares)	46,500,000	46,500,000
Common stock, issued (in shares)	12,867,736	12,812,377
Common stock, outstanding (in shares)	12,867,736	12,812,377
Preferred stock, authorized (in shares)	500,000	500,000
Preferred stock, issued (in shares)	0	0