Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 41,559	$ 38,103
Short-term investments	159,209	144,431
Accounts receivable, less reserves of $1,106 and $1,240 in 2012 and 2011, respectively	45,595	48,206
Inventories	27,807	28,098
Deferred income taxes	6,707	6,880
Prepaid expenses and other current assets	22,033	19,628
Total current assets	302,910	285,346
Long-term investments	183,965	174,906
Property, plant, and equipment, net	32,720	31,744
Deferred income taxes	15,632	15,919
Intangible assets, net	17,873	18,910
Goodwill	82,181	82,029
Other assets	2,700	3,027
Total assets	637,981	611,881
Current liabilities:
Accounts payable	7,341	7,098
Accrued expenses	23,431	32,290
Accrued income taxes	1,012	1,259
Deferred revenue and customer deposits	12,473	13,458
Total current liabilities	44,257	54,105
Reserve for income taxes	4,931	4,796
Commitments and contingencies (Note 7)
Shareholders' equity:
Common stock, $.002 par value - Authorized: 140,000 shares, issued: 42,835 and 42,223 shares in 2012 and 2011, respectively	86	84
Additional paid-in capital	154,922	135,668
Retained earnings	444,592	434,581
Accumulated other comprehensive loss, net of tax	(10,807)	(17,353)
Total shareholders' equity	588,793	552,980
Total liabilities and shareholders' equity	$ 637,981	$ 611,881