Cash, Cash Equivalents and Investments (Details) (USD $)	6 Months Ended
Jun. 29, 2013	Dec. 29, 2012
Cash, Cash Equivalents and Investments
Auction-rate securities guaranteed by the U.S. government	$ 10,400,000
Auction-rate securities privately insured	2,000,000
Auction-rate securities having credit rating 'AA'	6,000,000
Auction-rate securities having credit rating 'A'	2,000,000
Auction-rate securities having credit rating 'BBB'	4,400,000
Other-than-temporary impairment losses	0
Cash on hand, Cost	67,854,000	56,690,000
Cash on hand, Fair Value	67,854,000	56,690,000
Cash and cash equivalents, Cost	193,468,000	105,424,000
Cash and cash equivalents, Gross Unrealized Gains		2,000
Cash and cash equivalents, Fair Value	193,468,000	105,426,000
Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	125,614,000	48,734,000
Available-for-sale securities, Gross Unrealized Gains		2,000
Available-for-sale securities, Fair Value	125,614,000	48,736,000
Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	151,431,000	176,207,000
Available-for-sale securities, Gross Unrealized Losses	(96,000)	(12,000)
Available-for-sale securities, Gross Unrealized Gains	88,000	370,000
Available-for-sale securities, Fair Value	151,423,000	176,565,000
Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	12,425,000	12,525,000
Available-for-sale securities, Gross Unrealized Losses	(2,228,000)	(1,156,000)
Available-for-sale securities, Fair Value	10,197,000	11,369,000
U.S. Treasury bills \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		25,049,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value		25,050,000
Money market funds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	119,064,000	22,685,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	119,064,000	22,686,000
Certificates of deposit \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	5,550,000
Available-for-sale securities, Fair Value	5,550,000
Certificates of deposit \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	1,858,000
Available-for-sale securities, Fair Value	1,858,000
Commercial paper \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	1,000,000
Available-for-sale securities, Fair Value	1,000,000
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	13,040,000	59,089,000
Available-for-sale securities, Gross Unrealized Losses	(1,000)	(5,000)
Available-for-sale securities, Gross Unrealized Gains	38,000	267,000
Available-for-sale securities, Fair Value	13,077,000	59,351,000
Municipal bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		1,000,000
Available-for-sale securities, Fair Value		1,000,000
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	79,400,000	45,646,000
Available-for-sale securities, Gross Unrealized Losses	(95,000)	(7,000)
Available-for-sale securities, Gross Unrealized Gains	50,000	50,000
Available-for-sale securities, Fair Value	79,355,000	45,689,000
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	56,007,000	41,785,000
Available-for-sale securities, Fair Value	56,007,000	41,785,000
Asset-backed securities \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		15,058,000
Available-for-sale securities, Gross Unrealized Gains		11,000
Available-for-sale securities, Fair Value		15,069,000
U.S. government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		12,638,000
Available-for-sale securities, Gross Unrealized Gains		25,000
Available-for-sale securities, Fair Value		12,663,000
International government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	1,126,000	1,991,000
Available-for-sale securities, Gross Unrealized Gains		17,000
Available-for-sale securities, Fair Value	1,126,000	2,008,000
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	12,425,000	12,525,000
Available-for-sale securities, Gross Unrealized Losses	(2,228,000)	(1,156,000)
Available-for-sale securities, Fair Value	$ 10,197,000	$ 11,369,000

This element represents the amount of auction-rate securities that is guaranteed by the U.S. government.

No definition available.

Name:	slab_AuctionRateSecuritiesGuaranteedByUSGovernment
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of auction-rate securities having credit rating of 'A'.

+ References

No definition available.

+ Details

Name:	slab_AuctionRateSecuritiesHavingCreditRatingA
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of auction-rate securities having credit rating of 'AA'.

+ References

No definition available.

+ Details

Name:	slab_AuctionRateSecuritiesHavingCreditRatingAA
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of auction-rate securities having credit rating of 'BBB'.

+ References

No definition available.

+ Details

Name:	slab_AuctionRateSecuritiesHavingCreditRatingBBB
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of auction-rate securities that is privately insured.

+ References

No definition available.

+ Details

Name:	slab_AuctionRateSecuritiesPrivatelyInsured
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the adjusted cost of cash and cash equivalents that are considered available-for-sale and recorded at fair value.

+ References

No definition available.

+ Details

Name:	slab_CashAndCashEquivalentsAdjustedCost
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the unrealized gains from cash and cash equivalents.

+ References

No definition available.

+ Details

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Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents fair value of cash which is similar to carrying value of cash as of balance sheet date.

+ References

No definition available.

+ Details

Name:	slab_CashFairValueDisclosure
Namespace Prefix:	slab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt 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

No definition available.

+ Details

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

- Definition

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

+ References

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-Name Accounting Standards Codification

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+ Details

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

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References

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

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

- Definition

This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

+ Details

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

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Company may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months.

+ References

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

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-Glossary Cash

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-Glossary Cash Equivalents

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- Definition

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

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

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-Name FASB Staff Position (FSP)

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