CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Operating Activities:
Net income	$ 8,684	$ 10,609
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	7,408	6,841
Amortization of deferred financing costs	23	22
Deferred income taxes	994	1,341
Loss on disposition of property, plant and equipment	103	10
Stock-based compensation	541	414
Changes in operating assets and liabilities:
Trade receivables	(1,121)	(4,310)
Inventories	(438)	908
Prepaid expenses and other current assets	288	508
Other assets	3	(21)
Accounts payable and accrued expenses	(419)	92
Other liabilities	(202)	53
Net cash provided by operating activities	15,864	16,467
Investing Activities:
Purchase of property, plant and equipment	(4,760)	(3,887)
Proceeds from sale of property, plant and equipment	42	83
Net cash used in investing activities	(4,718)	(3,804)
Financing Activities:
Repayments of term loans	(2,500)	(2,500)
Purchase of treasury shares	(40,790)	(126)
Proceeds from exercise of stock options	75
Net cash used in financing activities	(43,215)	(2,626)
Net (decrease) increase in cash and cash equivalents	(32,069)	10,037
Cash and cash equivalents at beginning of period	53,372	36,223
Cash and cash equivalents at end of period	$ 21,303	$ 46,260