Share-Based Compensation - Narrative (Details) $ / shares in Units, $ in Thousands					3 Months Ended		12 Months Ended
		Apr. 27, 2018 shares	Oct. 05, 2016 shares	Feb. 26, 2014 $ / shares	Apr. 29, 2018 USD ($) $ / shares shares	Apr. 30, 2017 $ / shares	Jan. 27, 2019 USD ($) employee $ / shares shares		Jan. 28, 2018 $ / shares shares		Jan. 29, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized per the equity incentive plan							17,031,653
Aggregate unrecognized compensation for stock options | $							$ 3,200
Potential per share consideration due upon change in control | $ / shares							$ 40.00
Number of employees affected by modification of awards | employee							8
Number of shares affected (in shares)					159,000
Additional compensation cost | $					$ 2,800
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 | $							$ 21,500
Warrant vesting costs due to acceleration | $							$ 15,900
Number of securities called by warrants (in shares)							869,565
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							2 years 12 months
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period							3 years
Maximum number of shares which would be settled in shares							187,116
Remaining value of shares which would be settled in cash (in shares)							187,116
Target performance metrics for performance unit awards, fiscal year 2017							180.80%
Aggregate unrecognized compensation | $							$ 6,800
Period over which aggregate unrecognized compensation will be recognized							1 year 3 months
Weighted average fair value units granted (in dollars per share) | $ / shares	[1]						$ 32.93		$ 39.55		$ 17.51
Stock units granted (in shares)					200,442		287,000	[1]	215,857	[1]	231,000	[1]
Description of award vesting rights							one-third of the awards vesting each performance period
Percent of performance achievement of target for vested awards							158.10%
Percent of expected performance achievement of target for nonvested awards							158.10%
Total number of unvested shares (in shares)							203,000		363,000
Market performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average fair value units granted (in dollars per share) | $ / shares							$ 0.00
Stock units granted (in shares)							0
Total number of unvested shares (in shares)							0		154,000
Employee stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period							4 years
Aggregate unrecognized compensation | $							$ 63,700
Period over which aggregate unrecognized compensation will be recognized							2 years 4 months
Weighted average fair value units granted (in dollars per share) | $ / shares							$ 45.36		$ 36.96		$ 22.12
Stock units granted (in shares)							998,000		983,000		1,228,000
Total number of unvested shares (in shares)							2,204,000		2,175,000
Non-employee director stock unit awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total number of unvested shares (in shares)							12,257
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 | $							$ 2,845
Stock units granted (in shares)							43,000
Total number of unvested shares (in shares)							0		108,000
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 (in shares)							176,861
Subject to share settlement | Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock units granted (in shares)							244,000
Total number of unvested shares (in shares)							203,000		255,000
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) | $ / shares					$ 33.02	$ 38.01
Percent of performance achievement of target for vested awards							180.20%
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) | $ / shares					34.85	39.76
Percent of expected performance achievement of target for nonvested awards							180.20%
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) | $ / shares					$ 36.52	$ 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 (usd per share) | $ / shares				$ 35.00
Weighted average fair value units granted (in dollars per share) | $ / shares				$ 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 (usd per share) | $ / shares				$ 40.00
Weighted average fair value units granted (in dollars per share) | $ / shares				$ 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 | $							$ 9,200

[1] Restricted stock units granted includes awards that will be cash settled of 146,827 units in fiscal year 2019, 0 units in fiscal year 2018, and 115,500 units in fiscal year 2017.