1. Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Components of the Company's cash and cash equivalents and our short and long-term investments

	2017		2016
Cash and cash equivalents:
Cash deposits	$	12,730	$	10,724
Money market funds		17,406		9,298
Total cash and cash equivalents	$	30,136	$	20,022
Short-term investments:
Mutual funds (trading)	$	222		--
Commercial paper (held-to-maturity)		31,220		--
Certificates of deposit (held-to-maturity)		4,020	$	24,000
Corporate bonds (held-to-maturity)		6		80
Total short-term investments	$	35,468	$	24,080
Long-term investments:
Corporate bonds (held-to-maturity)	$	5,000	$	5,000
Equity securities (available-for-sale)		4,136		4,945
Total long-term investments	$	9,136	$	9,945
Total cash, cash equivalents and short and long-term investments	$	74,740	$	54,047

Major Components of Inventories

	December 31,
	2017		2016
Raw materials	$	13,545	$	12,984
Work in process		6,647		6,230
Finished goods		9,162		9,801
Total inventories	$	29,354	$	29,015

Summary of Property Plant and Equipment at Original Cost

	December 31,				Useful
	2017		2016		Lives
Land	$	5,511	$	5,260		—
Buildings		32,461		32,321	30-40 yrs
Machinery and equipment		129,108		122,832	3-15 yrs
Total property, plant and equipment	$	167,080	$	160,413

Current Accrued Liabilities

	December 31,
	2017		2016
Accrued payroll and related expenses	$	3,943	$	3,661
Accrued vacation		273		265
Other accrued liabilities		731		709
Total accrued liabilities	$	4,947	$	4,635