Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
OPERATING ACTIVITIES:
Net income	$ 45,429	$ 37,045	$ 28,223
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	22,199	20,898	19,611
Impairment of long-lived assets			1,550
Amortization of deferred financing costs	2	6	5
Deferred income taxes	2,527	1,524	4,313
(Gain) loss on disposition of property, plant and equipment	(312)	10	462
Stock-based compensation	2,636	2,236	1,915
Changes in operating assets and liabilities:
Trade receivables, net	(6,438)	(3,736)	1,109
Inventories, net	(4,294)	94	(1,390)
Prepaid expenses and other current assets	(191)	(999)	(106)
Other assets	8	(41)	3
Accounts payable and accrued expenses	2,701	(1,101)	2,579
Other liabilities	96	(247)	301
Net cash provided by operating activities	64,363	55,689	58,575
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(26,815)	(29,914)	(17,133)
Acquisition of a business, net of cash acquired	(5,630)		(8,392)
Proceeds from sale of property, plant and equipment	1,294	285	331
Net cash used in investing activities	(31,151)	(29,629)	(25,194)
FINANCING ACTIVITIES:
Cash dividends paid	(4,536)	(3,620)	(3,603)
Proceeds from exercise of stock options	120	84	81
Purchase of treasury shares	(767)	(731)	(557)
Net cash used in financing activities	(5,183)	(4,267)	(4,079)
Net increase in cash and cash equivalents	28,029	21,793	29,302
Cash and cash equivalents at beginning of period	105,355	83,562	54,260
Cash and cash equivalents at end of period	$ 133,384	$ 105,355	$ 83,562