Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income from consolidated operations	$ 19,750	$ 14,311	$ 9,210
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	8,172	7,831	5,635
(Gain) loss on sales of property, plant and equipment		(47)	7
Share-based compensation	1,591	1,212	1,068
Deferred income taxes	792	1,881	(1,019)
Changes in operating assets and liabilities:
Receivables, net	(327)	(2,556)	(132)
Inventories	1,300	(2,295)	1,288
Prepaid expenses	(98)	(249)	446
Refundable income taxes	2,006	(1,268)	(210)
Other assets	110	(76)	(228)
Accounts payable	(2,472)	1,113	93
Accrued expenses	25	1,472	974
Deferred revenue	67	35	91
Non-qualified deferred compensation plan and other liabilities	313	(44)	246
Net cash provided by operating activities	31,229	21,320	17,469
Cash flows from investing activities:
Additions to property, plant and equipment	(5,778)	(5,428)	(10,382)
Acquisition of Dieletrics, net of cash acquired		(76,978)
Proceeds from sale of property, plant and equipment	4	77	7
Net cash used in investing activities	(5,774)	(82,329)	(10,375)
Cash flows from financing activities:
Proceeds from advances on revolving line of credit		36,000
Payments on revolving line of credit	(8,000)	(28,000)
Proceeds from the issuance of long-term debt		20,000
Principal repayment of long-term debt	(17,143)	(2,857)	(856)
Proceeds from the exercise of stock options, net of shares presented for exercise	705	1,270	677
Payment of statutory withholding for stock options exercised and restricted stock units vested	(512)	(144)	(296)
Net cash (used in) provided by financing activities	(24,950)	26,269	(475)
Net change in cash and cash equivalents	505	(34,740)	6,619
Cash and cash equivalents at beginning of year	3,238	37,978	31,359
Cash and cash equivalents at end of year	$ 3,743	$ 3,238	$ 37,978