Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 27, 2013	Sep. 28, 2012
Cash flows from operating activities:
Net income	$ 20,817	$ 22,161
Adjustments to reconcile net income to net cash provided from (used in) operating activities:
Depreciation, depletion and amortization	30,842	28,923
Amortization of deferred financing costs in interest expense	501	487
Stock-based compensation expense	4,103	4,343
Changes in assets and liabilities net of acquired assets and liabilities:
Decrease (increase) in accounts receivable	3,122	(20,451)
Decrease (increase) in other receivables	21	4,393
Decrease (increase) in inventory	(7,496)	(23,795)
Decrease (increase) in prepaid and other current assets	4,653	(4,852)
Decrease (increase) in deferred income taxes	249	(812)
Increase (decrease) in accounts payable and accrued expenses	(21,216)	(12,805)
Increase (decrease) in unearned revenue	(1,082)	(1,316)
Increase (decrease) in interest and taxes payable	108	(577)
Increase (decrease) in long-term liabilities	1,152	(3,618)
Other-net	2,741	545
Net cash provided from (used in) operating activities	38,515	(7,374)
Cash flows from investing activities:
Payments for purchase of property, plant and equipment	(19,830)	(25,335)
Payments for mine development	(4,407)	(4,992)
Reimbursements for capital equipment under government contracts	0	991
Payments for purchase of business net of cash received	0	(3,894)
Proceeds from sale of property, plant and equipment	23	0
Other investments-net	20	1,742
Net cash used in investing activities	(24,194)	(31,488)
Cash flows from financing activities:
Proceeds from issuance (repayments) of short-term debt	(13,263)	16,505
Proceeds from issuance of long-term debt	70,333	32,305
Repayment of long-term debt	(62,789)	(7,740)
Debt issuance costs	(1,554)	0
Principal payments under capital lease obligations	(491)	(580)
Repurchase of common stock	0	(119)
Payment of dividends	(4,847)	(3,083)
Issuance of common stock under stock option plans	1,075	144
Tax benefit from stock compensation realization	1,664	77
Net cash (used in) provided from financing activities	(9,872)	37,509
Effects of exchange rate changes	(348)	(8)
Net change in cash and cash equivalents	4,101	(1,361)
Cash and cash equivalents at beginning of period	16,056	12,255
Cash and cash equivalents at end of period	$ 20,157	$ 10,894