Income Taxes (Details) - USD ($)	3 Months Ended		4 Months Ended	6 Months Ended		8 Months Ended	12 Months Ended
	Oct. 27, 2018	Oct. 28, 2017	Apr. 30, 2018	Oct. 27, 2018	Oct. 28, 2017	Dec. 31, 2017	Apr. 30, 2019	Apr. 30, 2018
Income taxes
U.S. federal statutory income tax rate (as a percent)			21.00%	30.40%		35.00%
Deferred tax expense								$ 3,300,000
Provision for income taxes	$ 1,211,000	$ 3,358,000		$ 3,778,000	$ 137,000
Effective tax benefit rate (as a percent)	13.50%	30.80%		11.60%	4.20%
Excess tax benefits	$ 357,000	$ 376,000		$ 1,507,000	$ 1,401,000
Expected
Income taxes
Decrease in effective tax rate							2.00%