CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
OPERATING ACTIVITIES:
Net income	$ 20,969	$ 21,063
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	14,391	12,646
Amortization of deferred financing costs	5	7
Deferred income taxes	4,369	3,999
Loss on disposition of property, plant and equipment	144	628
Stock-based compensation	1,344	1,104
Changes in operating assets and liabilities:
Trade receivables, net	(758)	(3,578)
Inventories, net	(1,242)	(391)
Prepaid expenses and other current assets	289	32
Other assets	165	85
Accounts payable and accrued expenses	2,296	681
Other liabilities	(65)	(96)
Net cash provided by operating activities	41,907	36,180
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(13,621)	(20,423)
Acquisition of a business	(8,392)
Proceeds from sale of property, plant and equipment	58	195
Net cash used in investing activities	(21,955)	(20,228)
FINANCING ACTIVITIES:
Cash dividends paid	(2,701)	(2,273)
Proceeds from exercise of stock options	81	75
Purchase of treasury shares	(282)	(241)
Net cash used in financing activities	(2,902)	(2,439)
Net increase in cash and cash equivalents	17,050	13,513
Cash and cash equivalents at beginning of period	54,260	67,218
Cash and cash equivalents at end of period	$ 71,310	$ 80,731