CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES:
Net income	$ 11,645	$ 11,161
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	9,453	8,404
Amortization of deferred financing costs	2	6
Deferred income taxes	2,484	2,619
Loss on disposition of property, plant and equipment	239	97
Stock-based compensation	842	691
Changes in operating assets and liabilities:
Trade receivables, net	1,756	(3,344)
Inventories, net	(1,034)	517
Prepaid expenses and other current assets	896	341
Other assets	40	50
Accounts payable and accrued expenses	779	(452)
Other liabilities	27	(54)
Net cash provided by operating activities	27,129	20,036
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(10,599)	(12,360)
Proceeds from sale of property, plant and equipment	46	461
Net cash used in investing activities	(10,553)	(11,899)
FINANCING ACTIVITIES:
Cash dividends paid	(1,800)	(1,517)
Proceeds from exercise of stock options	81	75
Purchase of treasury shares	(282)	(241)
Net cash used in financing activities	(2,001)	(1,683)
Net increase in cash and cash equivalents	14,575	6,454
Cash and cash equivalents at beginning of period	54,260	67,218
Cash and cash equivalents at end of period	$ 68,835	$ 73,672