CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
OPERATING ACTIVITIES:
Net income	$ 29,432	$ 20,969
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	15,632	14,391
Amortization of deferred financing costs	6	5
Deferred income taxes	2,049	4,369
Loss on sale of property, plant and equipment	41	144
Stock-based compensation	1,678	1,344
Changes in operating assets and liabilities:
Trade receivables, net	(6,263)	(758)
Inventories, net	450	(1,242)
Prepaid expenses and other current assets	844	289
Other assets	(86)	165
Accounts payable and accrued expenses	266	2,296
Other liabilities	78	(65)
Net cash provided by operating activities	44,127	41,907
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(23,731)	(13,621)
Acquisition of a business		(8,392)
Proceeds from sale of property, plant and equipment	171	58
Net cash used in investing activities	(23,560)	(21,955)
FINANCING ACTIVITIES:
Cash dividends paid	(2,715)	(2,701)
Proceeds from exercise of stock options	83	81
Purchase of treasury shares	(95)	(282)
Net cash used in financing activities	(2,727)	(2,902)
Net increase in cash and cash equivalents	17,840	17,050
Cash and cash equivalents at beginning of period	83,562	54,260
Cash and cash equivalents at end of period	$ 101,402	$ 71,310