Investments in Cash Equivalents and Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
Sep. 29, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 86,859	$ 114,809
Available For Sale Securities Net Unrealized Gains	0	1
Available For Sale Securities Net Unrealized Losses	0	(1)
Available-for-sale Securities	86,859	114,809
Maximum Term Of Available For Sale Securities	1	1
Marketable Securities, Realized Loss, Other than Temporary Impairments, Amount	0
Cash Equivalents [Member] \| Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	14,098	24,010
Available For Sale Securities Net Unrealized Gains	0	0
Available For Sale Securities Net Unrealized Losses	0	0
Available-for-sale Securities	14,098	24,010
Cash Equivalents [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,499	4,000
Available For Sale Securities Net Unrealized Gains	0	0
Available For Sale Securities Net Unrealized Losses	0	0
Available-for-sale Securities	3,499	4,000
Cash Equivalents [Member] \| US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	853
Available For Sale Securities Net Unrealized Gains	0
Available For Sale Securities Net Unrealized Losses	0
Available-for-sale Securities	853
Cash Equivalents [Member] \| Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	38,218	40,793
Available For Sale Securities Net Unrealized Gains	0	0
Available For Sale Securities Net Unrealized Losses	0	0
Available-for-sale Securities	38,218	40,793
Short Term Marketable Securities [Member] \| Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	14,934	12,704
Available For Sale Securities Net Unrealized Gains	0	1
Available For Sale Securities Net Unrealized Losses	0	0
Available-for-sale Securities	14,934	12,705
Short Term Marketable Securities [Member] \| Municipal Notes [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis		9,295
Available For Sale Securities Net Unrealized Gains		0
Available For Sale Securities Net Unrealized Losses		0
Available-for-sale Securities		9,295
Short Term Marketable Securities [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	4,999	16,506
Available For Sale Securities Net Unrealized Gains	0	0
Available For Sale Securities Net Unrealized Losses	0	(1)
Available-for-sale Securities	4,999	16,505
Short Term Marketable Securities [Member] \| US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	6,672	7,501
Available For Sale Securities Net Unrealized Gains	0	0
Available For Sale Securities Net Unrealized Losses	0	0
Available-for-sale Securities	6,672	7,501
Short Term Marketable Securities [Member] \| Certificates of Deposit [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	3,586
Available For Sale Securities Net Unrealized Gains	0
Available For Sale Securities Net Unrealized Losses	0
Available-for-sale Securities	$ 3,586

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Publisher FASB

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 12

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details