Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands	9 Months Ended
	Oct. 02, 2011		Oct. 02, 2010
Cash flows from operating activities:
Net income	$ 28,059		$ 10,467
Adjustments to reconcile net income to net cash provided (used) by operating activities:
Depreciation	2,881		2,319
Amortization	194		208
Accretion of asset retirement obligations	82		73
(Gain) loss on disposal of equipment	(4)		112
Stock-based compensation	6,190		3,202
Deferred income taxes	(17)		27
Changes in operating assets and liabilities:
Accounts receivable	(2,065)		1,114
Inventories	(11,527)		(8,075)
Prepaid expenses and other current assets	(484)		(2,506)
Other assets	1,371		(577)
Accounts payable	2,496		7,985
Deferred product and services income	(3,453)		7,107
Other current liabilities	(2,455)		(5,079)
Other liabilities	3,601		(1,760)
Net cash provided by operating activities	29,779		24,775
Cash flows from investing activities:
Capital expenditures	(3,020)		(4,677)
Purchase of investments in securities	(157,685)		(122,343)
Proceeds from maturities of investments	120,320		97,972
Net cash used in investing activities	(40,385)		(29,048)
Cash flows from financing activities:
Proceeds from notes payable	10,000		18,000
Repayment of notes payable	(12,000)		(18,000)
Proceeds from issuance of common stock for stock option exercises	12,980		4,453
Tax payment for issuance of common stock from release of restricted stock units	(1,268)		(48)
Net cash provided by financing activities	9,712		4,405
Net increase in cash and cash equivalents	(894)		132
Cash and cash equivalents at beginning of period	63,626	[1]	58,617
Cash and cash equivalents at end of period	62,732		58,749
Systems transferred from fixed assets to inventory	$ 34		$ 0

[1] The Balance Sheet as of December 31, 2010 has been derived from the audited financial statements at that date.