Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATING ACTIVITIES:
Net income	$ 22,186	$ 18,040	$ 13,670
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	13,781	13,611	13,475
Amortization of deferred financing costs	45	35	16
Deferred income taxes	3,654	3,090	1,682
Loss (gain) on sale of property, plant and equipment	96	11	(43)
Stock-based compensation	848	737	576
Changes in operating assets and liabilities, net of the effects of acquisitions of businesses:
Trade receivables	(1,756)	(474)	1,127
Inventories	(164)	(1,141)	2,837
Prepaid expenses and other current assets	18	244	(133)
Other assets	5	(118)	(32)
Accounts payable and accrued expenses	(294)	197	(1,306)
Other liabilities	88	(48)	(295)
Net cash provided by operating activities	38,507	34,184	31,574
INVESTING ACTIVITIES:
Purchase of property, plant and equipment	(9,413)	(9,328)	(6,653)
Proceeds from sale of property, plant and equipment	128	74	247
Net cash used in investing activities	(9,285)	(9,254)	(6,406)
FINANCING ACTIVITIES:
Repayments of revolving credit facilities, net			(4,688)
Repayments of term loans	(3,750)	(5,000)	(5,000)
Proceeds from exercise of stock options			166
Purchase of treasury shares	(8,323)	(173)	(100)
Tax benefits related to exercise of stock options			84
Net cash used in financing activities	(12,073)	(5,173)	(9,538)
Net increase in cash and cash equivalents	17,149	19,757	15,630
Cash and cash equivalents at beginning of year	36,223	16,466	836
Cash and cash equivalents at end of year	$ 53,372	$ 36,223	$ 16,466