Credit Facilities Narrative (Details) (USD $)	0 Months Ended	6 Months Ended
	May 02, 2013	Jul. 28, 2013	Jul. 29, 2012	Jun. 03, 2013	Mar. 20, 2012
Prior credit facilities, aggregate principal amount of term loans					$ 350,000,000
New credit facilities, maximum borrowing capacity	400,000,000
New credit facilities, amount outstanding	326,500,000
New credit facilities, debt discount	1,500,000
Prior credit facilities, repayment of outstanding obligations	327,500,000
New credit facilities, debt issuance cost	2,000,000
New credit facilities, contractual term	5 years
Prior credit facilities, write-off of deferred financing costs and original issue discount		8,773,000	0
New credit facilities, early term loan prepayment				26,000,000
Minimum [Member]
Interest coverage ratio		3.50
Maximum [Member]
Total leverage ratio		3.00
Base Rate [Member]
Description of variable rate basis	the highest of (a) the prime rate, (b) ½ of 1% above the federal funds effective rate or (c) one-month LIBOR (determined with respect to deposits in U.S. Dollars) plus 1%.
Base Rate [Member] | Minimum [Member]
Margin on variable rate	0.25%
Base Rate [Member] | Maximum [Member]
Margin on variable rate	1.25%
LIBOR [Member]
Basis spread on variable rate	1.00%
LIBOR [Member] | Minimum [Member]
Margin on variable rate	1.25%
LIBOR [Member] | Maximum [Member]
Margin on variable rate	2.25%
Federal Funds [Member]
Basis spread on variable rate	1.00%
CDOR [Member]
Description of variable rate basis	the sum of: (a) the rate determined by Administrative Agent with reference to the arithmetic average of the discount rate quotations of all institutions listed for CAD Dollar-denominated bankers’ acceptances displayed and identified on the “Reuters Screen CDOR Page” and (b) 0.10% per annum
Basis spread on variable rate	0.10%
CDOR [Member] | Minimum [Member]
Margin on variable rate	1.25%
CDOR [Member] | Maximum [Member]
Margin on variable rate	2.25%
Prior credit facilities, Term A Loans [Member]
Prior credit facilities, aggregate principal amount of term loans					100,000,000
Initial carrying amounts					99,500,000
Original issue discount on debt					500,000
Prior credit facilities, Term B Loans [Member]
Prior credit facilities, aggregate principal amount of term loans					250,000,000
Initial carrying amounts					247,500,000
Original issue discount on debt					2,500,000
New credit facilities, Term Loan [Member]
New credit facilities, maximum borrowing capacity	150,000,000
New credit facilities, amount outstanding	149,300,000
New credit facilities, Interest rate at period end		1.95%
Principal payments in the remainder of fiscal year 2014		9,400,000
Principal payments in fiscal year 2015		18,800,000
Principal payments in fiscal year 2016		18,800,000
Principal payments in fiscal year 2017		18,800,000
Principal payments in fiscal year 2018		24,400,000
Revolving Credit Facility [Member]
New credit facilities, maximum borrowing capacity	250,000,000
New credit facilities, amount outstanding	177,200,000
New credit facilities, Interest rate at period end		1.95%
Revolving Credit Facility [Member] | Minimum [Member]
New credit facilities, unused capacity, commitment fee percentage	0.20%
Revolving Credit Facility [Member] | Maximum [Member]
New credit facilities, unused capacity, commitment fee percentage	0.45%
Letter of Credit [Member]
New credit facilities, maximum borrowing capacity	40,000,000
Swingline Loans [Member]
New credit facilities, maximum borrowing capacity	25,000,000
Revolving Loans and Non US Dollars LC [Member]
New credit facilities, maximum borrowing capacity	40,000,000
Additional Term Loan or Increase in Revolver [Member] | Maximum [Member]
New credit facilities, maximum borrowing capacity	$ 100,000,000
United States of America, Dollars
Description of variable rate basis	(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.
Alternative Currencies, Except Canadian [Member]
Description of variable rate basis	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.
Canada, Dollars
Description of variable rate basis	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.