Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 01, 2012	Dec. 31, 2010
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 19,180	$ 18,423
Reconciliation to cash flows:
Depreciation and amortization	6,238	5,106
Deferred income taxes		333
Stock compensation expense	945	1,132
Loss (gain) from property disposals	(17)	(32)
Changes in operating accounts providing (using) cash:
Trade receivables	354	(2,015)
Inventories	(3,414)	(3,087)
Accounts payable	(5,616)	1,437
Accrued liabilities	(1,203)	(2,406)
Income taxes	3,526	4,882
Other	462	538
Net cash provided by operating activities	20,455	24,311
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property, plant, and equipment	(13,827)	(7,764)
Purchases of investments	(10,735)	(4,410)
Sale and maturities of investments	11,840	23,930
Acquisition of Vertex	(1,709)
Proceeds from property disposals	224	80
Net cash provided by (used in) investing activities	(14,207)	11,836
CASH FLOWS FROM FINANCING ACTIVITIES:
Cash dividends paid	(6,417)	(7,005)
Proceeds from the exercise of stock options	190
Excess tax benefit from share-based compensation	76
Proceeds from the sale of stock under the employee stock purchase plan	243
Net cash used in financing activities	(5,908)	(7,005)
NET INCREASE IN CASH AND CASH EQUIVALENTS	340	29,142
CASH AND CASH EQUIVALENTS, BEGINNING OF PERIOD	18,940	18,772
CASH AND CASH EQUIVALENTS, END OF PERIOD	19,280	47,914
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for income taxes	8,158	6,181
Noncash investing activities-
Capital expenditures in accounts payable	$ 1,103	$ 254