Summary of Significant Accounting Policies - Reconciliation of Net Income/(Loss) Amounts and Weighted Average Number of Common and Common Equivalent Shares Used to Determine Basic and Diluted Earnings(Loss) per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Aug. 23, 2020	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Earnings Per Share [Abstract]
Basic earnings/(loss)		$ 18,405	$ (96,201)	$ (9,521)
Diluted earnings/(loss)		$ 18,405	$ (96,201)	$ (9,521)
Basic		13,997,000	13,975,000	13,975,000
Effect of dilutive stock awards, Shares		228,000
Diluted earnings/(loss), Shares	0	14,225,000	13,975,000	13,975,000
Basic earnings/(loss), Per Share Amount		$ 1.31	$ (6.88)	$ (0.68)
Effect of dilutive stock awards, Per Share Amount		(0.02)
Diluted earnings/(loss), Per Share Amount		$ 1.29	$ (6.88)	$ (0.68)