Stock-based Compensation - Summary of Stock Options (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Apr. 25, 2020 USD ($) $ / shares shares
Number of Options
Beginning balance (in shares) | shares	1,556,000
Granted (in shares) | shares	1,318,000
Exercised (in shares) | shares	0
Canceled (in shares) | shares	(441,000)
Ending balance (in shares) | shares	2,433,000
Vested or expected to vest at end of year (in shares) | shares	2,349,000
Exercisable at end of year (in shares) | shares	402,000
Weighted- Average Exercise Price
Beginning balance (in usd per share) | $ / shares	$ 39.96
Granted (in usd per share) | $ / shares	22.22
Exercised (in usd per share) | $ / shares	0
Canceled (in usd per share) | $ / shares	46.94
Ending balance (in usd per share) | $ / shares	29.08
Vested or expected to vest at end of year (in usd per share) | $ / shares	29.28
Exercisable at end of year (in usd per share) | $ / shares	$ 41.65
Aggregate Intrinsic Value
Balance at end of year | $	$ 0
Vested or expected to vest at end of year | $	0
Exercisable at end of year | $	$ 0