Cash, Cash Equivalents and Investments (Details) (USD $)	12 Months Ended
Jan. 03, 2015	Dec. 28, 2013
Cash, Cash Equivalents and Investments
Auction-rate securities guaranteed by the U.S. government	$ 6,000,000
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
Other-than-temporary impairment losses	0
Cash on hand, Cost	52,144,000us-gaap_Cash	45,544,000us-gaap_Cash
Cash on hand, Fair Value	52,144,000slab_CashFairValueDisclosure	45,544,000slab_CashFairValueDisclosure
Cash and cash equivalents, Cost	141,705,000slab_CashAndCashEquivalentsAdjustedCost	95,800,000slab_CashAndCashEquivalentsAdjustedCost
Cash and cash equivalents, Gross Unrealized Gains	1,000
Cash and cash equivalents, Fair Value	141,706,000	95,800,000
Available-for-sale securities
Total Cost	290,926,000	50,256,000
Available-for-sale securities, Fair Value		50,256,000us-gaap_AvailableForSaleSecurities
Cash Equivalents:
Available-for-sale securities
Total Cost	89,561,000
Available-for-sale securities, Gross Unrealized Gains	1,000
Available-for-sale securities, Fair Value	89,562,000
Short-term Investments:
Available-for-sale securities
Total Cost	193,365,000	179,365,000
Available-for-sale securities, Gross Unrealized Losses	(73,000)	(15,000)
Available-for-sale securities, Gross Unrealized Gains	197,000	243,000
Available-for-sale securities, Fair Value	193,489,000	179,593,000
Long-term Investments:
Available-for-sale securities
Total Cost	8,000,000	12,425,000
Available-for-sale securities, Gross Unrealized Losses	(581,000)	(1,793,000)
Available-for-sale securities, Fair Value	7,419,000	10,632,000
Money market funds \| Cash Equivalents:
Available-for-sale securities
Total Cost	71,415,000	39,538,000
Available-for-sale securities, Fair Value	71,415,000	39,538,000
Commercial paper \| Cash Equivalents:
Available-for-sale securities
Total Cost	5,348,000	2,499,000
Available-for-sale securities, Fair Value	5,348,000	2,499,000
Commercial paper \| Short-term Investments:
Available-for-sale securities
Total Cost	8,995,000	3,748,000
Available-for-sale securities, Fair Value	8,995,000	3,748,000
Certificates of deposit \| Cash Equivalents:
Available-for-sale securities
Total Cost	7,739,000	7,768,000
Available-for-sale securities, Fair Value	7,739,000	7,768,000
Certificates of deposit \| Short-term Investments:
Available-for-sale securities
Total Cost	250,000
Available-for-sale securities, Fair Value	250,000
Municipal bonds \| Cash Equivalents:
Available-for-sale securities
Total Cost	1,756,000	451,000
Available-for-sale securities, Gross Unrealized Gains	1,000
Available-for-sale securities, Fair Value	1,757,000	451,000
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Total Cost	129,005,000	119,289,000
Available-for-sale securities, Gross Unrealized Losses	(25,000)	(11,000)
Available-for-sale securities, Gross Unrealized Gains	172,000	182,000
Available-for-sale securities, Fair Value	129,152,000	119,460,000
Corporate bonds \| Cash Equivalents:
Available-for-sale securities
Total Cost	1,101,000
Available-for-sale securities, Fair Value	1,101,000
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Total Cost	33,043,000	17,788,000
Available-for-sale securities, Gross Unrealized Losses	(35,000)	(4,000)
Available-for-sale securities, Gross Unrealized Gains	25,000	60,000
Available-for-sale securities, Fair Value	33,033,000	17,844,000
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Total Cost	12,915,000	38,025,000
Available-for-sale securities, Fair Value	12,915,000	38,025,000
Asset-backed securities \| Short-term Investments:
Available-for-sale securities
Total Cost	5,380,000	515,000
Available-for-sale securities, Gross Unrealized Losses	(3,000)
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	5,377,000	516,000
International government bonds \| Short-term Investments:
Available-for-sale securities
Total Cost	2,526,000
Available-for-sale securities, Gross Unrealized Losses	(10,000)
Available-for-sale securities, Fair Value	2,516,000
U.S. government bonds \| Cash Equivalents:
Available-for-sale securities
Total Cost	1,000,000
Available-for-sale securities, Fair Value	1,000,000
U.S. government bonds \| Short-term Investments:
Available-for-sale securities
Total Cost	650,000
Available-for-sale securities, Fair Value	650,000
US government agency \| Cash Equivalents:
Available-for-sale securities
Total Cost	1,202,000
Available-for-sale securities, Fair Value	1,202,000
US government agency \| Short-term Investments:
Available-for-sale securities
Total Cost	601,000
Available-for-sale securities, Fair Value	601,000
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Total Cost	8,000,000	12,425,000
Available-for-sale securities, Gross Unrealized Losses	(581,000)	(1,793,000)
Available-for-sale securities, Fair Value	$ 7,419,000	$ 10,632,000

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 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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

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-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ 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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

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-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

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+ Details

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

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Fair value portion 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. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

+ Details

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

- Details

Name:	us-gaap_InvestmentsAndCashAbstract
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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Balance Type:	debit
Period Type:	duration

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Period Type:	duration

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