Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Jul. 29, 2017	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Stock-Based Compensation
Expense recognized		$ 9,879	$ 10,551	$ 9,647
Stock Options
Stock-Based Compensation
Cash received for exercises of stock options		$ 4,400	$ 3,600	400
Number of Shares
Outstanding at beginning of period (in shares)	1,509,000	1,509,000
Granted (in shares)	573,591	574,000
Canceled (in shares)		(40,000)
Exercised (in shares)		(206,000)
Outstanding at end of period (in shares)		1,837,000	1,509,000
Exercisable (in shares)		732,000
Weighted Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 22.70	$ 22.70
Granted (in dollars per share)		27.25
Canceled (in dollars per share)		26.58
Exercised (in dollars per share)		21.40
Outstanding at end of period (in dollars per share)		24.18	$ 22.70
Exercisable (in dollars per share)		$ 20.57
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		5 years 10 months 24 days
Aggregate Intrinsic Value, Outstanding		$ 9,407	$ 7,638
Aggregate Intrinsic Value, Exercised		2,152	$ 4,900	$ 600
Aggregate Intrinsic Value, Exercisable		6,388
Unrecognized compensation cost		$ 1,900
Period for recognition of unrecognized compensation costs		1 year 6 months
Vested during the period (in shares)		400,000
Fair value assumptions
Risk-free interest rate (as a percent)		1.84%	1.30%	1.54%
Dividend rate (as a percent)		1.61%	1.54%	1.20%
Expected life in years		5 years	5 years	5 years
Stock price volatility (as a percent)		32.12%	38.87%	44.37%
Fair value per share (in dollars per share)		$ 7.16	$ 7.99	$ 9.69
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		$ 4,200	$ 3,400	$ 3,200
Stock Options | Former Long-Term Equity Award Plan
Stock-Based Compensation
Award expiration term		10 years