Fair Value of Financial Instruments (Details 4) (Assets and liabilities measured at fair value on recurring basis, Auction rate securities, USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 27, 2014	Sep. 27, 2014
Assets and liabilities measured at fair value on recurring basis \| Auction rate securities
Fair value assets reconciliation of changes
Balance at the beginning of the period	$ 10,993	$ 10,632
Gain included in other comprehensive income	512	873
Balance at the end of the period	$ 11,505	$ 11,505

Amount of gain (loss) recognized in other comprehensive income (loss) for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1a)

-URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration