Income Taxes (Details) - USD ($)	3 Months Ended		4 Months Ended	8 Months Ended	12 Months Ended
	Jul. 28, 2018	Jul. 29, 2017	Apr. 30, 2018	Dec. 31, 2017	Apr. 30, 2019	Apr. 30, 2018
Income taxes
U.S. federal statutory income tax rate (as a percent)	30.40%		21.00%	35.00%
Deferred tax expense						$ 3,300,000
Provision (benefit) for income taxes	$ 2,567,000	$ (3,221,000)
Effective tax benefit rate (as a percent)	10.90%	42.30%
Exess tax benefits	$ 1,150,000	$ 1,025,000
Expected
Income taxes
Decrease in effective tax rate					2.00%