Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2012	Apr. 01, 2011
Consolidated Statements of Cash Flows [Abstract]
Net income (loss)	$ 6,118	$ 11,818
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation, depletion and amortization	11,951	11,893
Amortization of deferred financing costs in interest expense	157	117
Stock-based compensation expense	1,411	990
Changes in assets and liabilities net of acquired assets and liabilities:
Decrease (increase) in accounts receivable	(21,792)	(13,094)
Decrease (increase) in other receivables	2,473	942
Decrease (increase) in inventory	(1,381)	(21,198)
Decrease (increase) in prepaid and other current assets	(988)	(1,280)
Decrease (increase) in deferred income taxes	(1,295)
Increase (decrease) in accounts payable and accrued expenses	(19,527)	(12,004)
Increase (decrease) in unearned revenue	(784)	651
Increase (decrease) in interest and taxes payable	2,276	2,054
Increase (decrease) in long-term liabilities	(1,079)	(1,623)
Other - net	(512)	(20)
Net cash used in operating activities	(22,972)	(20,754)
Cash flows from investing activities:
Payments for purchase of property, plant and equipment	(9,282)	(3,869)
Payments for mine development	(159)	(127)
Reimbursements for capital equipment under government contracts	563	1,112
Payments for purchase of business net of cash received	(3,955)
Proceeds from sale of property, plant and equipment		31
Other investments - net	1,742
Net cash (used in) investing activities	(11,091)	(2,853)
Cash flows from financing activities:
Proceeds from issuance of short-term debt	17,160	8,561
Proceeds from issuance of long-term debt	20,105	20,000
Repayment of long-term debt	(247)	(10,000)
Principal payments under capital lease obligations	(191)	(257)
Issuance of common stock under stock option plans	128	637
Tax benefit from stock compensation realization	67	376
Net cash provided from financing activities	37,022	19,317
Effects of exchange rate changes	(68)	193
Net change in cash and cash equivalents	2,891	(4,097)
Cash and cash equivalents at beginning of period	12,255	16,104
Cash and cash equivalents at end of period	$ 15,146	$ 12,007