Cash, Cash Equivalents and Investments (Details) (USD $)	3 Months Ended
Apr. 04, 2015	Jan. 03, 2015
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	48,302,000us-gaap_Cash	52,144,000us-gaap_Cash
Cash on hand, Fair Value	48,302,000slab_CashFairValueDisclosure	52,144,000slab_CashFairValueDisclosure
Cash and cash equivalents, Cost	112,710,000slab_CashAndCashEquivalentsAdjustedCost	141,705,000slab_CashAndCashEquivalentsAdjustedCost
Cash and cash equivalents, Gross Unrealized Gains		1,000
Cash and cash equivalents, Fair Value	112,710,000	141,706,000
Available-for-sale securities
Available-for-sale securities, Cost	221,071,000
Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	64,408,000	89,561,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	64,408,000	89,562,000
Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	148,663,000	193,365,000
Available-for-sale securities, Gross Unrealized Losses	(21,000)	(73,000)
Available-for-sale securities, Gross Unrealized Gains	153,000	197,000
Available-for-sale securities, Fair Value	148,795,000	193,489,000
Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,000,000	8,000,000
Available-for-sale securities, Gross Unrealized Losses	(599,000)	(581,000)
Available-for-sale securities, Fair Value	7,401,000	7,419,000
Money market funds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	58,808,000	71,415,000
Available-for-sale securities, Fair Value	58,808,000	71,415,000
Certificates of deposit \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	5,148,000	7,739,000
Available-for-sale securities, Fair Value	5,148,000	7,739,000
Certificates of deposit \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		250,000
Available-for-sale securities, Fair Value		250,000
Commercial paper \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		5,348,000
Available-for-sale securities, Fair Value		5,348,000
Commercial paper \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	4,898,000	8,995,000
Available-for-sale securities, Fair Value	4,898,000	8,995,000
Municipal bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	452,000	1,756,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	452,000	1,757,000
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	122,794,000	129,005,000
Available-for-sale securities, Gross Unrealized Losses	(19,000)	(25,000)
Available-for-sale securities, Gross Unrealized Gains	142,000	172,000
Available-for-sale securities, Fair Value	122,917,000	129,152,000
US government agency \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		1,202,000
Available-for-sale securities, Fair Value		1,202,000
US government agency \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		601,000
Available-for-sale securities, Fair Value		601,000
Corporate bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		1,101,000
Available-for-sale securities, Fair Value		1,101,000
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	10,109,000	33,043,000
Available-for-sale securities, Gross Unrealized Losses	(2,000)	(35,000)
Available-for-sale securities, Gross Unrealized Gains	10,000	25,000
Available-for-sale securities, Fair Value	10,117,000	33,033,000
U.S. government bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		1,000,000
Available-for-sale securities, Fair Value		1,000,000
U.S. government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		650,000
Available-for-sale securities, Fair Value		650,000
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,615,000	12,915,000
Available-for-sale securities, Fair Value	8,615,000	12,915,000
Asset-backed securities \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost		5,380,000
Available-for-sale securities, Gross Unrealized Losses		(3,000)
Available-for-sale securities, Fair Value		5,377,000
International government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	2,247,000	2,526,000
Available-for-sale securities, Gross Unrealized Losses		(10,000)
Available-for-sale securities, Gross Unrealized Gains	1,000
Available-for-sale securities, Fair Value	2,248,000	2,516,000
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	8,000,000	8,000,000
Available-for-sale securities, Gross Unrealized Losses	(599,000)	(581,000)
Available-for-sale securities, Fair Value	$ 7,401,000	$ 7,419,000

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

Name:	slab_CashAndCashEquivalentsGrossUnrealizedGains
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)

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

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-Publisher FASB

-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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

+ 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

Name:	us-gaap_Cash
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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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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Period Type:	duration

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- Details

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