Credit Facilities - Narrative (Details) (USD $)				12 Months Ended		0 Months Ended							0 Months Ended									0 Months Ended			3 Months Ended	12 Months Ended									0 Months Ended
	Jun. 03, 2013	May 02, 2013	Mar. 20, 2012	Jan. 26, 2014 Minimum	Jan. 26, 2014 Maximum	May 02, 2013 Base Rate [Member]	Jun. 03, 2013 Base Rate [Member] Minimum	May 02, 2013 Base Rate [Member] Maximum	May 02, 2013 LIBOR [Member]	May 02, 2013 LIBOR [Member] Minimum	May 02, 2013 LIBOR [Member] Maximum	May 02, 2013 Federal Funds [Member]	May 02, 2013 CDOR [Member]	May 02, 2013 CDOR [Member] Minimum	May 02, 2013 CDOR [Member] Maximum	Mar. 20, 2012 Prior credit facilities, Term A Loans [Member]	Mar. 20, 2012 Prior credit facilities, Term B Loans [Member]	Jan. 26, 2014 New credit facilities, Term Loan	May 02, 2013 New credit facilities, Term Loan	Jan. 26, 2014 New credit facilities, Revolving Credit Facility	May 02, 2013 New credit facilities, Revolving Credit Facility	May 02, 2013 New credit facilities, Revolving Credit Facility Minimum	May 02, 2013 New credit facilities, Revolving Credit Facility Maximum	May 02, 2013 New credit facilities [Member]	Jul. 28, 2013 New credit facilities [Member]	Jan. 26, 2014 Prior credit facilities [Member]	May 02, 2013 Prior credit facilities [Member]	Oct. 27, 2013 New credit facilities, Letter of Credit [Member]	May 02, 2013 New credit facilities, Letter of Credit [Member]	Oct. 27, 2013 New credit facilities, Swingline Loans [Member]	May 02, 2013 New credit facilities, Swingline Loans [Member]	Oct. 27, 2013 New credit facilities, Revolving Loans and Non US Dollars LC [Member]	May 02, 2013 New credit facilities, Revolving Loans and Non US Dollars LC [Member]	May 02, 2013 Additional Term Loan or Increase in Revolver [Member] Maximum	May 02, 2013 United States of America, Dollars	May 02, 2013 Alternative Currencies, Except Canadian [Member]	May 02, 2013 Canada, Dollars
Prior credit facilities, aggregate principal amount of term loans			$ 350,000,000													$ 100,000,000	$ 250,000,000
Initial carrying amounts																(99,500,000)	(247,500,000)
Original issue discount on debt																500,000	2,500,000
New credit facilities, maximum borrowing capacity		400,000,000																	150,000,000		250,000,000								40,000,000.0		25,000,000.0		40,000,000.0	100,000,000
New credit facilities, Amount Outstanding		326,600,000																	149,300,000	178,000,000	177,300,000							0		0		0
New credit facilities, debt discount																								1,400,000
New credit facilities, debt discount expensed																									800,000
New credit facilities, debt discount capitalized																								600,000
Prior credit facilities, repayment of outstanding obligations		327,500,000
New credit facilities, deferred financing costs																								2,200,000
New credit facilities, deferred financing costs expensed																									1,000,000
Deferred finance costs capitalized																								1,200,000			1,700,000
New credit facilities, contractual term																								5 years
Prior credit facilities, gains (losses) on modification of debt																										(7,100,000)
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%.							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.																						(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.
Margin on variable rate							0.25%	1.25%		1.25%	2.25%			1.25%	2.25%
Basis spread on variable rate									1.00%			1.00%	0.10%
New credit facilities, unused capacity, commitment fee percentage																						0.20%	0.45%
New credit facilities, interest rate at period end																		1.91%		1.91%
New credit facilities, early term loan prepayment	$ 26,000,000
Interest Coverage Ratio				3.50
Total Leverage Ratio					3.00