CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
OPERATING ACTIVITIES:
Net income	$ 13,834	$ 10,600
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	12,032	11,916
Amortization of deferred financing costs	11	25
Deferred income taxes	311	(353)
Loss (gain) on sale of property, plant and equipment	107	(137)
Stock-based compensation	778	908
Changes in operating assets and liabilities:
Trade receivables, net	(3,496)	(1,770)
Inventories, net	2,015	(685)
Prepaid expenses and other current assets	700	1,623
Other assets	5	(20)
Accounts payable and accrued expenses	(341)	208
Other liabilities	(86)	585
Net cash provided by operating activities	25,870	22,900
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(12,230)	(8,080)
Proceeds from sale of property, plant and equipment	126	263
Net cash used in investing activities	(12,104)	(7,817)
FINANCING ACTIVITIES:
Repayment of term loans		(16,667)
Cash dividends paid	(2,087)	(2,099)
Proceeds from exercise of stock options	153	28
Purchase of treasury shares	(2,818)	(158)
Net cash used in financing activities	(4,752)	(18,896)
Net increase (decrease) in cash and cash equivalents	9,014	(3,813)
Cash and cash equivalents at beginning of period	59,926	58,332
Cash and cash equivalents at end of period	$ 68,940	$ 54,519