Business, Basis of Presentation and Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Apr. 30, 2018
Buildings | Minimum
Property and equipment
Estimated useful life	25 years
Buildings | Maximum
Property and equipment
Estimated useful life	39 years
Furniture, fixtures and automobiles | Minimum
Property and equipment
Estimated useful life	3 years
Furniture, fixtures and automobiles | Maximum
Property and equipment
Estimated useful life	5 years
Warehouse and delivery equipment | Minimum
Property and equipment
Estimated useful life	4 years
Warehouse and delivery equipment | Maximum
Property and equipment
Estimated useful life	10 years