Income per Share - Schedule of Computation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2020	Oct. 26, 2019	Oct. 31, 2020	Oct. 26, 2019
Earnings Per Share [Abstract]
Net Income	$ 38.6	$ 23.8	$ 59.3	$ 52.1
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Denominator for Basic Income per Share-Weighted Average Shares Outstanding and Vested/Unissued RSUs	38,106,793	37,587,742	37,971,668	37,561,098
Dilutive Potential Common Shares-Employee Stock Options, PSAs and RSUs	20,745	151,446	171,310	142,025
Denominator for Diluted Income per Share	38,127,538	37,739,188	38,142,978	37,703,123
Basic and Diluted Income per Share:
Basic Income per Share (in dollars per share)	$ 1.01	$ 0.63	$ 1.56	$ 1.39
Diluted Income per Share (in dollars per share)	$ 1.01	$ 0.63	$ 1.56	$ 1.38
Number of Anti-dilutive Potentially Issuable Shares Excluded from Diluted Common Shares Outstanding	1,017,000	755,493	559,334	759,368