Share-Based Compensation - Narrative (Details)				3 Months Ended	12 Months Ended
		Oct. 05, 2016 USD ($) $ / shares mo shares	Feb. 26, 2014 $ / shares	Apr. 30, 2017 $ / shares	Jan. 28, 2018 USD ($) $ / shares shares	Jan. 29, 2017 USD ($) $ / shares shares	Jan. 31, 2016 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized per the equity incentive plan | shares					17,031,653
Aggregate unrecognized compensation for stock options | $					$ 2,600,000
Potential per share consideration due upon change in control					$ 40.00
Number of employees affected by modification of awards					12
Incremental cost related to modification of awards | $					$ 0
Maximum number of shares subject to purchase under warrants | shares		1,086,957
Common stock, par value		$ 0.01			$ 0.01	$ 0.01
Fair value of warrant shares | $		$ 30,000,000
Number of trading days used to determine average closing price of shares subject to warrants		10
Exercise price of warrants (per share)		$ 0.01
Percent of warrants vested upon issuance		10.00%
Number of months in milestone period of warrants | mo		30
Warrants, contractual term		7 years			7 years
Reason for issuing to warrants		The Warrant was issued by the Company to Comcast in connection with an agreement between the parties regarding the intended trial deployment by Comcast of a low-power wide-area Network ("LPWAN") in the United States, based on the Company’s LoRa® devices and wireless radio frequency technology.
Number of performance tranches of warrants		5
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield					0.00%	0.00%	0.00%
Period over which aggregate unrecognized compensation will be recognized					1 year 11 months
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period					3 years
Performance condition, highest potential performance level					200.00%
Maximum number of shares which would be settled in shares | shares					219,000
Remaining value of shares which would be settled in cash | shares					219,000
Target performance metrics for performance unit awards, fiscal year 2017					190.00%
Aggregate unrecognized compensation | $					$ 5,900,000
Period over which aggregate unrecognized compensation will be recognized					1 year 2 months
Weighted average fair value units granted (in dollars per share)	[1]				$ 39.55	$ 17.51	$ 28.60
Stock units granted (in shares) | shares	[1]				215,857	231,000	235,000
Description of award vesting rights					one-third of the awards vesting each performance period
Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value units granted (in dollars per share)					$ 0.00
Stock units granted (in shares) | shares					0
Employee stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Aggregate unrecognized compensation | $					$ 47,500,000
Period over which aggregate unrecognized compensation will be recognized					2 years 4 months
Weighted average fair value units granted (in dollars per share)					$ 36.96	$ 22.12	$ 20.79
Stock units granted (in shares) | shares					983,000	1,228,000	1,032,000
Minimum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					3 years
Maximum | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					4 years
Contractual term of equity share options					10 years
Subject to cash settlement | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase (decrease) in liability | $					$ 4,791,000
Stock units granted (in shares) | shares					0
Subject to cash settlement | Non-employee director stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					1 year
Vested but unsettled stock units | shares					197,313
Subject to share settlement | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units granted (in shares) | shares					216,000
Subject to share settlement | Non-employee director stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period					1 year
Tranche One | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period					1 year
Weighted average fair value units granted (in dollars per share)				$ 38.01
Percent of performance achievement of target for vested awards					58.20%
Tranche Two | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period					2 years
Weighted average fair value units granted (in dollars per share)				39.76
Percent of expected performance achievement of target for nonvested awards					58.20%
Share-based Compensation Award, Tranche Three [Member] | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period					3 years
Weighted average fair value units granted (in dollars per share)				$ 40.89
Chief Executive Officer | Tranche One | Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield							0.00%
Share-based compensation, terms of award			The award is eligible to vest during the period commencing February 26, 2014 and ending February 26, 2019 (the “Performance Period”) as follows: 30% of the restricted stock units covered by the award will vest if, during any consecutive 120 calendar day period that commences and ends during the Performance Period, the average per-share closing price of the Company’s common stock equals or exceeds $35.00 (“Tranche 1”) and the award will vest in full if, during any consecutive 120 calendar day period that commences and ends during the Performance Period, the average per-share closing price of the Company’s common stock equals or exceeds $40.00 (“Tranche 2”). The award will also vest if a majority change in control of the Company occurs during the Performance Period and, in connection with such event, the Company’s stockholders become entitled to receive per-share consideration having a value equal to or greater than $40.00.
Percentage of award that will vest upon satisfaction of performance condition			30.00%
Award performance period			120 days
Minimum closing share price used to determine market condition			$ 35.00
Weighted average fair value units granted (in dollars per share)			$ 17.26				$ 17.26
Chief Executive Officer | Tranche Two | Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield							0.00%
Percentage of award that will vest upon satisfaction of performance condition			100.00%
Award performance period			120 days
Minimum closing share price used to determine market condition			$ 40.00
Weighted average fair value units granted (in dollars per share)			$ 14.88				$ 14.88
Other long-term liabilities | Subject to cash settlement | Non-employee director stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation liability, long-term | $					$ 7,500,000
Warrant [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of warrants (per share)						$ 27.74
Warrant Shares outstanding | shares						978
Aggregate unrecognized compensation related to Warrant Shares | $						$ 20,600,000
Number of shares underlying the Warrant that vested | shares					109,000
Number of shares underlying the warrant that exercised | shares					109,000

[1] Restricted stock units granted includes awards that will be cash settled of 0 units in fiscal year 2018, 115,500 units in fiscal year 2017, and 90,500 units in fiscal year 2016.