CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES:
Net income	$ 39,111	$ 33,746	$ 23,016
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation and amortization	9,127	7,745	6,147
(Gain) Loss on disposal of property, plant and equipment	(21)	156	(608)
Provision for doubtful accounts	15	214	86
Issuance of non-employee director shares	150	150	150
Deferred tax provision	1,708	568	(868)
Changes in operating assets and liabilities:
Accounts receivable	(19,605)	(19,353)	(6,668)
Inventories	5,453	(23,865)	(2,844)
Prepaid expenses	(1,529)	989	765
Other assets	609	60	8
Accounts payable	(2,165)	19,425	(5,806)
Accrued liabilities	2,279	2,062	575
Net cash flows from operating activities	35,132	21,897	13,953
INVESTING ACTIVITIES:
Purchases of property, plant and equipment	(17,391)	(13,342)	(24,693)
Proceeds from sale of property, plant and equipment	328	141	1,303
Net cash flows from investing activities	(17,063)	(13,201)	(23,390)
FINANCING ACTIVITIES:
Net proceeds (payments) under credit facility	(10,002)	5,000	5,000
Payments of cash dividends	(8,208)	(8,200)	(8,188)
Net proceeds (payments) on other long-term obligations	(367)	56	146
Finance lease obligation payments	(20)
Proceeds from exercise of stock options		179	606
Net cash flows from financing activities	(18,597)	(2,965)	(2,436)
EFFECT OF EXCHANGE RATE CHANGES ON CASH AND TEMPORARY INVESTMENTS	(437)	(589)	2,653
NET CHANGE IN CASH AND TEMPORARY INVESTMENTS	(965)	5,142	(9,220)
CASH AND TEMPORARY INVESTMENTS, beginning of period	27,037	21,895	31,115
CASH AND TEMPORARY INVESTMENTS, end of period	26,072	27,037	21,895
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash payments for interest	3,249	2,437	1,877
Cash payments for income taxes, net of refunds	$ 10,067	$ 7,457	$ 11,605