Cash, Cash Equivalents and Investments (Details) (USD $)	Jul. 02, 2011	Jan. 01, 2011
Cash, Cash Equivalents and Investments
Auction-rate securities guaranteed by the U.S. government	$ 17,400,000
Auction-rate securities privately insured	2,000,000
Auction-rate securities having credit rating 'AAA'	17,400,000
Auction-rate securities having credit rating 'A'	2,000,000
Cash on hand, Cost	34,590,000	40,644,000
Cash on hand, Fair Value	34,590,000	40,644,000
Available-for-sale securities
Cash and cash equivalents, Adjusted Cost	134,826,000	138,566,000
Cash and cash equivalents, Gross Unrealized Losses	(2,000)
Cash and cash equivalents, Gross Unrealized Gains		1,000
Cash and cash equivalents, Fair Value	134,824,000	138,567,000
Money market funds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	98,736,000	45,167,000
Available-for-sale securities, Fair Value	98,736,000	45,167,000
U.S. Treasury bills \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	500,000	50,096,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	500,000	50,097,000
U.S. Treasury bills \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	11,898,000	6,998,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	11,898,000	6,999,000
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	80,806,000	88,183,000
Available-for-sale securities, Gross Unrealized Losses	(17,000)	(46,000)
Available-for-sale securities, Gross Unrealized Gains	443,000	381,000
Available-for-sale securities, Fair Value	81,232,000	88,518,000
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	36,725,000	39,425,000
Available-for-sale securities, Fair Value	36,725,000	39,425,000
U.S. government agency \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	1,000,000
Available-for-sale securities, Gross Unrealized Losses	(2,000)
Available-for-sale securities, Fair Value	998,000
U.S. government agency \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	10,043,000	34,635,000
Available-for-sale securities, Gross Unrealized Losses		(5,000)
Available-for-sale securities, Gross Unrealized Gains	27,000	50,000
Available-for-sale securities, Fair Value	10,070,000	34,680,000
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	47,342,000	38,408,000
Available-for-sale securities, Gross Unrealized Losses	(3,000)	(18,000)
Available-for-sale securities, Gross Unrealized Gains	115,000	24,000
Available-for-sale securities, Fair Value	47,454,000	38,414,000
International government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	7,815,000	10,792,000
Available-for-sale securities, Gross Unrealized Losses	(1,000)
Available-for-sale securities, Gross Unrealized Gains	5,000	38,000
Available-for-sale securities, Fair Value	7,819,000	10,830,000
Certificates of deposit \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	1,570,000	5,744,000
Available-for-sale securities, Gross Unrealized Losses		(2,000)
Available-for-sale securities, Fair Value	1,570,000	5,742,000
Commercial paper \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost		2,659,000
Available-for-sale securities, Fair Value		2,659,000
Commercial paper \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	1,998,000	2,687,000
Available-for-sale securities, Fair Value	1,998,000	2,687,000
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Long-term investment interest, low end of range (as a percent)	0.19%
Long-term investment interest, high end of range (as a percent)	3.15%
Available-for-sale securities, Cost	19,425,000	19,725,000
Available-for-sale securities, Gross Unrealized Losses	(2,229,000)	(2,225,000)
Available-for-sale securities, Fair Value	17,196,000	17,500,000
Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	100,236,000	97,922,000
Available-for-sale securities, Gross Unrealized Losses	(2,000)
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	100,234,000	97,923,000
Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	198,197,000	226,872,000
Available-for-sale securities, Gross Unrealized Losses	(21,000)	(71,000)
Available-for-sale securities, Gross Unrealized Gains	590,000	494,000
Available-for-sale securities, Fair Value	198,766,000	227,295,000
Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	19,425,000	19,725,000
Available-for-sale securities, Gross Unrealized Losses	(2,229,000)	(2,225,000)
Available-for-sale securities, Fair Value	$ 17,196,000	$ 17,500,000

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

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'.

+ 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 'AAA'.

+ Details

Name:	slab_AuctionRateSecuritiesHavingCreditRatingAAA
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.

+ 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.

+ 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.

+ Details

Name:	slab_CashAndCashEquivalentsGrossUnrealizedGains
Namespace Prefix:	slab
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ Details

Name:	slab_CashAndCashEquivalentsGrossUnrealizedLosses
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.

+ Details

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

- Definition

The high end of the range of interest rates for investments.

+ Details

Name:	slab_InvestmentInterestRateHighEndOfRange
Namespace Prefix:	slab
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The low end of the range of interest rates for investments.

+ Details

Name:	slab_InvestmentInterestRateLowEndOfRange
Namespace Prefix:	slab
Data Type:	num:percentItemType
Balance Type:	na
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.

+ Details

Name:	us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

For an unclassified balance sheet, this item represents investments in debt and equity securities which are 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 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26610-111562

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 12
-Subparagraph b
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15E
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 22
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15D
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15C
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 16
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6379932&loc=d3e22054-111558

+ Details

Name:	us-gaap_AvailableForSaleSecurities
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
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 22
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 13, 19
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: 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=6872113&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableforsaleSecuritiesGrossUnrealizedGain
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.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesGrossUnrealizedLosses1
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Unrestricted cash available for day-to-day operating needs, for an entity that has cash equivalents, but does not aggregate cash equivalents with cash on the balance sheet.

+ 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 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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 Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 7
-Footnote 1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

+ Details

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

- Details

Name:	us-gaap_CashAndCashEquivalentsAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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
-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 FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 7, 8, 9, 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 7
-Footnote 1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 8
-Footnote 2
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration