Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Jul. 25, 2015	Apr. 30, 2016	Apr. 25, 2015	Apr. 26, 2014
Stock-Based Compensation
Expense recognized		$ 9,647	$ 11,377	$ 14,475
Cash received for exercises of stock options		420	1,397	3,565
Stock Options
Stock-Based Compensation
Cash received for exercises of stock options		$ 400	$ 1,400	3,600
Number of Shares
Outstanding, at beginning of period (in shares)	1,039,000	1,039,000
Granted (in shares)	426,539	427,000
Canceled (in shares)		(16,000)
Exercised (in shares)		(39,000)
Outstanding, at end of period (in shares)		1,411,000	1,039,000
Exercisable (in shares)		597,000
Weighted Average Exercise Price
Outstanding, at beginning of period (in dollars per share)	$ 16.15	$ 16.15
Granted (in dollars per share)		26.69
Canceled (in dollars per share)		25.71
Exercised (in dollars per share)		10.75
Outstanding, at end of period (in dollars per share)		19.39	$ 16.15
Exercisable (in dollars per share)		$ 13.26
Additional information
Weighted Average Remaining Contractual Term, Outstanding		7 years 4 months 24 days	7 years 7 months 6 days
Weighted Average Remaining Contractual Term, Exercisable		6 years
Aggregate Intrinsic Value, Outstanding		$ 9,489	$ 11,773
Aggregate Intrinsic Value, Exercised		622	$ 2,000	$ 8,300
Aggregate Intrinsic Value, Exercisable		7,529
Unrecognized compensation cost		$ 2,600
Period for recognition of unrecognized compensation costs		1 year 9 months 18 days
Vested during the period (in shares)		300,000
Fair value assumptions
Risk-free interest rate (as a percent)		1.54%	1.59%	0.84%
Dividend rate (as a percent)		1.20%	1.00%	0.84%
Expected life in years		5 years	5 years	5 years
Stock price volatility (as a percent)		44.37%	54.40%	81.27%
Fair value per share (in dollars per share)		$ 9.69	$ 10.45	$ 11.63
Stock Options | Minimum
Stock-Based Compensation
Purchase price of common stock at date of grant (as a percent)		100.00%
Vesting period		1 year
Stock Options | Maximum
Stock-Based Compensation
Vesting period		4 years
Stock Options | Selling, General and Administrative Expense
Stock-Based Compensation
Expense recognized		$ 3,200	$ 3,000	$ 2,100
Stock Options | Former Long-Term Equity Award Plan | Minimum
Stock-Based Compensation
Award expiration term		5 years
Stock Options | Former Long-Term Equity Award Plan | Maximum
Stock-Based Compensation
Award expiration term		10 years