Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 28, 2013	Jun. 29, 2012
Cash flows from operating activities:
Net income	$ 15,694	$ 14,047
Adjustments to reconcile net income to net cash provided from (used in) operating activities:
Depreciation, depletion and amortization	18,656	20,440
Amortization of deferred financing costs in interest expense	325	325
Stock-based compensation expense	2,676	2,828
Changes in assets and liabilities net of acquired assets and liabilities:
Decrease (increase) in accounts receivable	(5,116)	(5,502)
Decrease (increase) in other receivables	(40)	3,873
Decrease (increase) in inventory	(2,617)	(21,953)
Decrease (increase) in prepaid and other current assets	11,104	(1,235)
Decrease (increase) in deferred income taxes	1,166	(1,360)
Increase (decrease) in accounts payable and accrued expenses	(27,143)	(12,942)
Increase (decrease) in unearned revenue	(1,077)	(1,470)
Increase (decrease) in interest and taxes payable	177	200
Increase (decrease) in long-term liabilities	2,409	(6,459)
Other-net	1,906	161
Net cash provided from (used in) operating activities	18,120	(9,047)
Cash flows from investing activities:
Payments for purchase of property, plant and equipment	(13,023)	(17,957)
Payments for mine development	(4,382)	(822)
Reimbursements for capital equipment under government contracts	0	991
Payments for purchase of business net of cash received	0	(3,953)
Proceeds from sale of property, plant and equipment	67	0
Other investments-net	20	1,742
Net cash used in investing activities	(17,318)	(19,999)
Cash flows from financing activities:
Proceeds from issuance (repayments) of short-term debt	(12,729)	16,322
Proceeds from issuance of long-term debt	70,240	25,207
Repayment of long-term debt	(55,541)	(7,494)
Debt issuance costs	(1,301)	0
Principal payments under capital lease obligations	(329)	(383)
Payment of dividends	(3,198)	(1,550)
Issuance of common stock under stock option plans	849	139
Tax benefit from stock compensation realization	1,316	73
Net cash (used in) provided from financing activities	(693)	32,314
Effects of exchange rate changes	(439)	(93)
Net change in cash and cash equivalents	(330)	3,175
Cash and cash equivalents at beginning of period	16,056	12,255
Cash and cash equivalents at end of period	$ 15,726	$ 15,430