Derivative Financial Instruments (Details) (USD $)	9 Months Ended
Sep. 29, 2012	Sep. 29, 2012 Long-term obligations and other liabilities	Dec. 31, 2011 Long-term obligations and other liabilities
Derivative Financial Instruments
Description of variable rate	LIBOR
Notional value of interest rate swap agreement hedging headquarters lease through July 2017	$ 100,000,000
Notional value of interest rate swap agreement hedging headquarters lease	50,100,000
Derivative financial instrument
Fair value of interest rate swap		$ 699,000	$ 1,998,000

Aggregate notional amount of all interest rate derivatives designated as hedging instruments in cash flow hedges. Notional amount refers to the monetary amount specified in the interest rate derivative contract.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

Name:	us-gaap_NotionalAmountOfInterestRateCashFlowHedgeDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant