Cash, Cash Equivalents and Investments (Details) (USD $)	3 Months Ended
Mar. 30, 2013	Dec. 29, 2012
Cash, Cash Equivalents and Investments
Auction-rate securities guaranteed by the U.S. government	$ 10,500,000
Auction-rate securities privately insured	2,000,000
Auction-rate securities having credit rating 'AAA'	4,500,000
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	32,034,000	56,690,000
Cash on hand, Fair Value	32,034,000	56,690,000
Cash and cash equivalents, Cost	79,263,000	105,424,000
Cash and cash equivalents, Gross Unrealized Gains		2,000
Cash and cash equivalents, Fair Value	79,263,000	105,426,000
Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	47,229,000	48,734,000
Available-for-sale securities, Gross Unrealized Gains		2,000
Available-for-sale securities, Fair Value	47,229,000	48,736,000
Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	229,459,000	176,207,000
Available-for-sale securities, Gross Unrealized Losses	(19,000)	(12,000)
Available-for-sale securities, Gross Unrealized Gains	368,000	370,000
Available-for-sale securities, Fair Value	229,808,000	176,565,000
Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	12,450,000	12,525,000
Available-for-sale securities, Gross Unrealized Losses	(1,261,000)	(1,156,000)
Available-for-sale securities, Fair Value	11,189,000	11,369,000
U.S. Treasury bills \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	325,000	25,049,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	325,000	25,050,000
U.S. Treasury bills \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	20,322,000
Available-for-sale securities, Gross Unrealized Gains	1,000
Available-for-sale securities, Fair Value	20,323,000
Money market funds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	44,590,000	22,685,000
Available-for-sale securities, Gross Unrealized Gains		1,000
Available-for-sale securities, Fair Value	44,590,000	22,686,000
Corporate bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	61,607,000	59,089,000
Available-for-sale securities, Gross Unrealized Losses	(7,000)	(5,000)
Available-for-sale securities, Gross Unrealized Gains	253,000	267,000
Available-for-sale securities, Fair Value	61,853,000	59,351,000
Municipal bonds \| Cash Equivalents:
Available-for-sale securities
Available-for-sale securities, Cost	2,314,000	1,000,000
Available-for-sale securities, Fair Value	2,314,000	1,000,000
Municipal bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	52,978,000	45,646,000
Available-for-sale securities, Gross Unrealized Losses	(10,000)	(7,000)
Available-for-sale securities, Gross Unrealized Gains	65,000	50,000
Available-for-sale securities, Fair Value	53,033,000	45,689,000
Variable-rate demand notes \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	64,185,000	41,785,000
Available-for-sale securities, Fair Value	64,185,000	41,785,000
Asset-backed securities \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	15,751,000	15,058,000
Available-for-sale securities, Gross Unrealized Losses	(2,000)
Available-for-sale securities, Gross Unrealized Gains	8,000	11,000
Available-for-sale securities, Fair Value	15,757,000	15,069,000
U.S. government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	12,633,000	12,638,000
Available-for-sale securities, Gross Unrealized Gains	25,000	25,000
Available-for-sale securities, Fair Value	12,658,000	12,663,000
International government bonds \| Short-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	1,983,000	1,991,000
Available-for-sale securities, Gross Unrealized Gains	16,000	17,000
Available-for-sale securities, Fair Value	1,999,000	2,008,000
Auction rate securities \| Long-term Investments:
Available-for-sale securities
Available-for-sale securities, Cost	12,450,000	12,525,000
Available-for-sale securities, Gross Unrealized Losses	(1,261,000)	(1,156,000)
Available-for-sale securities, Fair Value	$ 11,189,000	$ 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

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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'.

+ References

No definition available.

+ Details

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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

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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

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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

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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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- Definition

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

+ References

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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

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- 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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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

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

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-Glossary Cash

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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 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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- 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

+ Details

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