Credit Facility, Maximum Borrowing Capacity

No definition available.

Name:	smtc_CreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	smtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Margin on Variable Rate

+ References

No definition available.

+ Details

Name:	smtc_MarginOnVariableRate
Namespace Prefix:	smtc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Potential Term Loan Prepayment Payable

+ References

No definition available.

+ Details

Name:	smtc_PotentialTermLoanPrepaymentPayable
Namespace Prefix:	smtc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-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 Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

+ Details

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

- Definition

Amount of debt issuance costs (for example, but not limited to, legal, accounting, broker, and regulatory fees).

+ References

No definition available.

+ Details

Name:	us-gaap_DebtIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-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 Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)

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

+ Details

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

Subsequent Events - Narrative (Details) (USD $)	0 Months Ended		0 Months Ended					0 Months Ended				3 Months Ended		3 Months Ended		3 Months Ended
Subsequent Events - Narrative (Details) (USD $)	Mar. 20, 2012	Apr. 28, 2013	May 02, 2013 Base Rate [Member]	Mar. 20, 2012 Base Rate [Member]	Mar. 20, 2012 LIBOR [Member]	May 02, 2013 Federal Funds [Member]	Mar. 20, 2012 Federal Funds [Member]	May 02, 2013 United States of America, Dollars [Member]	May 02, 2013 Alternative Currencies, Except Canadian [Member]	May 02, 2013 Canada, Dollars [Member]	May 02, 2013 Subsequent Event [Member]	Apr. 28, 2013 Subsequent Event [Member]	May 02, 2013 Subsequent Event [Member] LIBOR [Member]	Apr. 28, 2013 Subsequent Event [Member] Minimum [Member]	May 02, 2013 Subsequent Event [Member] Minimum [Member] CDOR [Member]	Apr. 28, 2013 Subsequent Event [Member] Maximum [Member]	May 02, 2013 Subsequent Event [Member] Maximum [Member] CDOR [Member]	May 02, 2013 Subsequent Event [Member] Term Loan [Member]	May 02, 2013 Subsequent Event [Member] Letter of Credit [Member]	May 02, 2013 Subsequent Event [Member] Swingline Loans [Member]	May 02, 2013 Subsequent Event [Member] Revolving Loans and Non-US Dollars LC [Member]	May 02, 2013 Subsequent Event [Member] Additional Term Loan or Increase in Revolver [Member] Maximum [Member]	May 02, 2013 Subsequent Event [Member] United States of America, Dollars [Member] Minimum [Member] Base Rate [Member]	May 02, 2013 Subsequent Event [Member] United States of America, Dollars [Member] Minimum [Member] LIBOR [Member]	May 02, 2013 Subsequent Event [Member] United States of America, Dollars [Member] Maximum [Member] Base Rate [Member]	May 02, 2013 Subsequent Event [Member] United States of America, Dollars [Member] Maximum [Member] LIBOR [Member]	May 02, 2013 Subsequent Event [Member] Alternative Currencies, Except Canadian [Member] Minimum [Member] LIBOR [Member]	May 02, 2013 Subsequent Event [Member] Alternative Currencies, Except Canadian [Member] Maximum [Member] LIBOR [Member]
Subsequent Event [Line Items]
Aggregate principal amount of credit facilities											$ 400,000,000
Debt instrument, face amount	350,000,000																	150,000,000				100,000,000
Aggregate principal amount of revolving commitments											250,000,000								40,000,000	25,000,000	40,000,000
Debt issuance cost	8,900,000										3,500,000	600,000
Unamortized debt costs		6,500,000
Remaining original issue discount on debt		2,200,000
Early term loan prepayment payable		$ 26,000,000
Description of variable rate basis	(i) LIBOR for interest periods of 1, 2, 3 or 6 months or, subject to certain conditions, 9 or 12 months (“LIBOR”) or (ii) the highest of (a) the prime rate, (b) the federal funds effective rate plus 1/2% and (c) one-month LIBOR plus 1.00% ("Base Rate")		(a) the prime rate, (b) ½ of 1% above the federal funds effective rate and (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1%	the highest of (a) the prime rate, (b) the federal funds effective rate plus 1/2% and (c) one-month LIBOR plus 1.00%	LIBOR for interest periods of 1, 2, 3 or 6 months or, subject to certain conditions, 9 or 12 months			(1) the Base Rate (as defined below) plus a margin ranging from 0.25% to 1.25% depending upon Semtech’s consolidated leverage ratio or (2) LIBOR (determined with respect to deposits in U.S. Dollars) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.	a rate per annum equal to LIBOR (determined with respect to deposits in the applicable Alternative Currency) for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio.	a rate per annum equal to the CDOR Rate for an interest period to be selected by Semtech plus a margin ranging from 1.25% to 2.25% depending upon Semtech’s consolidated leverage ratio
Basis spread on variable rate					1.00%	0.50%	0.50%						1.00%
Margin on variable rate															1.25%		2.25%						0.25%	1.25%	1.25%	2.25%	1.25%	2.25%
Unused capacity commitment fee percentage														0.20%		0.45%