Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions					3 Months Ended	12 Months Ended
	Mar. 05, 2019 $ / shares shares	Apr. 27, 2018 shares	Oct. 05, 2016 shares	Feb. 26, 2014	Apr. 29, 2018 USD ($) employee shares	Jan. 26, 2020 USD ($) $ / shares shares	Jan. 27, 2019 USD ($) $ / shares shares	Jan. 28, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value on grant date (in dollars per share) | $ / shares							$ 14.53	$ 10.70
Number of shares authorized per the equity incentive plan						17,031,653
Aggregate unrecognized compensation for stock options | $						$ 1.9
Number of employees affected by modification of awards | employee					8
Number of shares affected (in shares)					159,000
Additional compensation cost | $					$ 2.8
Maximum number of shares subject to purchase under warrants			1,086,957
Number of shares underlying the Warrant that vested		586,956
Warrant vesting costs | $							$ 21.5
Warrant vesting costs due to acceleration | $							$ 15.9
Number of securities called by warrants (in shares)							869,565
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period over which aggregate unrecognized compensation will be recognized						2 years 2 months 12 days
Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)						79,245
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 59.49
Stock units granted (in shares)						266,000	200,442	215,857
Total number of unvested shares (in shares)						257,000	203,000
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate unrecognized compensation | $						$ 8.4
Period over which aggregate unrecognized compensation will be recognized						1 year 7 months 6 days
Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period							3 years
Percentage of award that will vest upon satisfaction of performance condition							180.80%
Total number of unvested shares (in shares)						0
Awards settled value | $						$ 9.3
Employee stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Awards vested (in shares)						892,000
Aggregate unrecognized compensation | $						$ 71.8
Period over which aggregate unrecognized compensation will be recognized						2 years 4 months 24 days
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 47.88
Stock units granted (in shares)						921,000
Total number of unvested shares (in shares)						2,102,000	2,204,000
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 Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)						187,116
Subject to share settlement | Performance Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)						187,116
Tranche One | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						1 year
Performance period						1 year
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 55.82
Tranche Two | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						2 years
Performance period						2 years
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 59.36
Tranche Three | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						3 years
Performance period						3 years
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 61.45
Tranche Four | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						4 years
Performance period						4 years
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 62.98
Vesting January 26, 2020 | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards scheduled to vest (in shares)						214,100
Chief Executive Officer | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate unrecognized compensation | $						$ 4.8
Period over which aggregate unrecognized compensation will be recognized	1 year 1 month 6 days
Potential per share consideration due upon change in control | $ / shares						$ 71.00
Stock units granted (in shares)	320,000
Chief Executive Officer | Tranche One | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of award that will vest upon satisfaction of performance condition	30.00%
Award performance period	30 days
Minimum closing share price used to determine market condition (usd per share) | $ / shares	$ 71.00
Weighted average fair value units granted (in dollars per share) | $ / shares	$ 44.32
Chief Executive Officer | Tranche One | Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
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.
Chief Executive Officer | Tranche Two | Market Performance Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award performance period	30 days
Minimum closing share price used to determine market condition (usd per share) | $ / shares	$ 95.00
Weighted average fair value units granted (in dollars per share) | $ / shares	$ 33.19
Chief Executive Officer | Tranche Two | Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of award that will vest upon satisfaction of performance condition				100.00%
Non-employee director stock unit awards | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						1 year
Awards vested (in shares)						26,000
Stock units vested but unsettled						190,873
Share-based compensation liability, long-term | $						$ 10.5
Weighted average fair value units granted (in dollars per share) | $ / shares						$ 50.55
Stock units granted (in shares)						26,000
Total number of unvested shares (in shares)						26,000	26,000
Non-employee director stock unit awards | Subject to cash settlement | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)						14,000
Stock units granted (in shares)						14,000
Total number of unvested shares (in shares)						14,000	14,000
Non-employee director stock unit awards | Subject to share settlement | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awards vested (in shares)						12,000
Stock units granted (in shares)						12,000
Total number of unvested shares (in shares)						12,000	12,000