Stock-Based Compensation - Activity (Details) - 2016 Equity Plan $ / shares in Units, $ in Thousands	12 Months Ended
	Jan. 25, 2020 USD ($) $ / shares shares
Options
Outstanding, beginning of year (in shares) | shares	7,758,832
Granted (in shares) | shares	778,797
Exercised (in shares) | shares	(406,509)
Forfeited or expired (in shares) | shares	(2,305,604)
Outstanding, end of year (in shares) | shares	5,825,516
Exercisable, end of year (in shares) | shares	4,506,048
Weighted Average Exercise Price
Outstanding, beginning of year (in dollars per share) | $ / shares	$ 21.43
Granted (in dollars per share) | $ / shares	14.33
Exercised (in dollars per share) | $ / shares	14.81
Forfeited or expired (in dollars per share) | $ / shares	36.94
Outstanding, end of year (in dollars per share) | $ / shares	14.80
Exercisable, end of year (in dollars per share) | $ / shares	$ 12.63
Weighted Average Remaining Contractual Term
Outstanding, end of year (in years)	4 years 3 days
Exercisable, end of year (in years)	3 years 5 months 15 days
Aggregate Intrinsic Value
Outstanding, end of year, aggregate intrinsic value | $	$ 7,684
Exercisable, end of year, aggregate intrinsic value | $	$ 6,520