Fair Value of Financial Instruments (Details 2) (Auction rate securities, USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 29, 2012
Quantitative information for Level 3 Fair Value Measurements Assets
Fair value Assets	11,418
Weighted Average \| Discounted cash flow
Quantitative information for Level 3 Fair Value Measurements Assets
Estimated yield (as a percent)	1.25%
Expected holding period	10 years
Estimated discount rate (as a percent)	2.74%

Represents the estimated interest rates, used as an input to measure fair value.

No definition available.

Name:	slab_FairValueInputsEstimatedInterestRates
Namespace Prefix:	slab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the expected holding period, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	slab_FairValueInputsExpectedHoldingPeriods
Namespace Prefix:	slab_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the liquidity discount, used as an input to measure fair value.

+ References

No definition available.

+ Details

Name:	slab_FairValueInputsLiquidityDiscount
Namespace Prefix:	slab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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

- Details

Name:	us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration