Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities:
Net income	$ 24,664	$ 39,979	$ 46,427
Adjustments to reconcile net income to net cash provided from operating activities:
Depreciation, depletion and amortization	37,046	43,635	35,394
Amortization of deferred financing costs in interest expense	649	559	538
Stock-based compensation expense	5,889	5,000	4,100
Derivative financial instruments ineffectiveness	0	0	598
Deferred tax (benefit) expense	(2,462)	(1,668)	13,623
Changes in assets and liabilities net of acquired assets and liabilities:
Decrease (increase) in accounts receivable	(8,913)	26,818	(50,386)
Decrease (increase) in other receivables	4,197	(630)	7,084
Decrease (increase) in inventory	(18,880)	(30,016)	(23,112)
Decrease (increase) in prepaid and other current assets	483	(7,571)	(3,566)
Increase (decrease) in accounts payable and accrued expenses	1,472	(2,580)	7,002
Increase (decrease) in unearned revenue	(1,491)	661	1,938
Increase (decrease) in interest and taxes payable	(2,324)	(5,891)	2,048
Increase (decrease) in long-term liabilities	(5,053)	(15,993)	(8,736)
Other - net	3,343	4,503	(1,911)
Net cash provided from operating activities	38,620	56,806	31,041
Cash flows from investing activities:
Payments for purchase of property, plant and equipment	(34,088)	(28,187)	(42,314)
Payments for mine development	(10,573)	(560)	(11,348)
Reimbursement for capital spending under government contract	991	5,386	21,944
Payments for purchase of business less cash received	(3,894)	(22,448)	(20,605)
Proceeds from transfer of acquired inventory to consignment line	0	0	5,667
Proceeds from sale of property, plant and equipment	0	54	77
Other investments - net	4,201	(4,274)	60
Net cash (used in) investing activities	(43,363)	(50,029)	(46,519)
Cash flows from financing activities:
Issuance (repayment) of short-term debt	8,594	(6,950)	(8,406)
Proceeds from issuance of long-term debt	32,403	118,582	80,000
Repayment of long-term debt	(27,986)	(116,425)	(50,000)
Principal payments under capital lease obligations	(749)	(812)	(779)
Payments of Ordinary Dividends, Common Stock	(4,615)	0	0
Deferred financing costs	0	(2,637)	(220)
Repurchase of common stock	(119)	(3,776)	(3,527)
Issuance of common stock under stock option plans	158	735	2,631
Tax benefit from stock compensation realization	817	658	121
Net cash provided from (used in) financing activities	8,503	(10,625)	19,820
Effects of exchange rate changes on cash and cash equivalents	41	(1)	(491)
Net change in cash and cash equivalents	3,801	(3,849)	3,851
Cash and cash equivalents at beginning of year	12,255	16,104	12,253
Cash and cash equivalents at end of year	$ 16,056	$ 12,255	$ 16,104