Elements of Deferred Income Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred income tax assets (liabilities)
- Depreciation & amortization	$ (3,665)	$ (236)
- Reserves for doubtful accounts	115	139
- Inventory reserve	218	304
- Non qualified stock options	409	247
- Net operating losses	1,450	2,078
Total	$ (1,473)	$ 2,532