Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
OPERATING ACTIVITIES:
Net income	$ 16,423	$ 22,186	$ 18,040
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	15,044	13,781	13,611
Amortization of deferred financing costs	46	45	35
Deferred income taxes	2,131	3,654	3,090
Loss on sale of property, plant and equipment	145	96	11
Stock-based compensation	1,082	848	737
Changes in operating assets and liabilities, net of the effects of acquisitions of businesses:
Trade receivables, net	1,043	(1,756)	(474)
Inventories	(3,363)	(164)	(1,141)
Prepaid expenses and other current assets	392	18	244
Other assets	4	5	(118)
Accounts payable and accrued expenses	(1,086)	(294)	197
Other liabilities	(174)	88	(48)
Net cash provided by operating activities	31,687	38,507	34,184
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(8,292)	(9,413)	(9,328)
Proceeds from sale of property, plant and equipment	42	128	74
Net cash used in investing activities	(8,250)	(9,285)	(9,254)
FINANCING ACTIVITIES:
Repayments of term loans	(6,250)	(3,750)	(5,000)
Proceeds from exercise of stock options	75
Purchase of treasury shares	(40,847)	(8,323)	(173)
Net cash used in financing activities	(47,022)	(12,073)	(5,173)
Net (decrease) increase in cash and cash equivalents	(23,585)	17,149	19,757
Cash and cash equivalents at beginning of year	53,372	36,223	16,466
Cash and cash equivalents at end of year	$ 29,787	$ 53,372	$ 36,223