CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
OPERATING ACTIVITIES:
Net income	$ 4,066	$ 2,365
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	3,992	3,962
Amortization of deferred financing costs	4	11
Deferred income taxes	58	7
Loss on sale of property, plant and equipment	47	30
Stock-based compensation	223	268
Changes in operating assets and liabilities:
Trade receivables, net	(948)	1,416
Inventories, net	956	(450)
Prepaid expenses and other current assets	350	793
Other assets	1
Accounts payable and accrued expenses	(815)	(1,020)
Other liabilities	(52)	141
Net cash provided by operating activities	7,882	7,523
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(3,935)	(3,424)
Proceeds from sale of property, plant and equipment	28	66
Net cash used in investing activities	(3,907)	(3,358)
FINANCING ACTIVITIES:
Repayment of term loans		(1,250)
Cash dividends paid	(696)	(700)
Proceeds from exercise of stock options	154
Purchase of treasury shares	(2,733)	(78)
Net cash used in financing activities	(3,275)	(2,028)
Net increase in cash and cash equivalents	700	2,137
Cash and cash equivalents at beginning of period	59,926	58,332
Cash and cash equivalents at end of period	$ 60,626	$ 60,469