Share-Based Compensation - Summary of Activity for Stock Settled Non-Employee Directors Stock Unit Awards (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Oct. 30, 2016	Oct. 25, 2015	Oct. 30, 2016	Oct. 25, 2015	Jan. 31, 2016
Weighted Average Grant Date Fair Value (per unit)
Increase to deferred tax liability		$ 0	$ 74	$ 0	$ 172
Subject To Share Settlement [Member] | Non-employee director stock unit awards [Member]
Number of Units
Beginning balance (in shares)				24
Stock units granted (in shares)				21
Stock units vested (in shares)				(25)
Stock units forfeited (in shares)				0
Ending balance (in shares)		20		20		24
Weighted Average Grant Date Fair Value (per unit)
Beginning balance				$ 19.70
Stock units granted (in dollars per share)				23.40
Stock units vested (in dollars per share)				24.16
Warrant shares forfeited (in dollars per share)				0.00
Ending balance		$ 23.67		$ 23.67		$ 19.70
Aggregate Intrinsic Value
Aggregate intrinsic value of stock units vested	[1]			$ 616
Aggregate Unrecognized Compensation
Beginning balance				186
Ending balance		$ 312		$ 312		$ 186
Period Over Which Expected to be Recognized (in years)
Weighted average period over which expected to be recognized				7 months		5 months

[1] the value of Semtech Corporation stock on the date that the restricted stock unit vested.