CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating Activities:
Net income	$ 7,382	$ 8,684
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	7,381	7,408
Amortization of deferred financing costs	23	23
Deferred income taxes	689	994
(Gain) loss on sale of property, plant and equipment	(8)	103
Stock-based compensation	460	541
Changes in operating assets and liabilities:
Trade receivables, net	(3,172)	(1,121)
Inventories	(50)	(438)
Prepaid expenses and other current assets	(371)	288
Other assets	(13)	3
Accounts payable and accrued expenses	167	(419)
Other liabilities	12	(202)
Net cash provided by operating activities	12,500	15,864
Investing Activities:
Purchase of property, plant and equipment	(4,012)	(4,760)
Proceeds from sale of property, plant and equipment	51	42
Net cash used in investing activities	(3,961)	(4,718)
Financing Activities:
Repayments of term loans	(1,250)	(2,500)
Purchase of treasury shares	(212)	(40,790)
Proceeds from exercise of stock options	9	75
Net cash used in financing activities	(1,453)	(43,215)
Net increase (decrease) in cash and cash equivalents	7,086	(32,069)
Cash and cash equivalents at beginning of period	29,787	53,372
Cash and cash equivalents at end of period	$ 36,873	$ 21,303