Financial instruments and credit risk concentrations (Details)	12 Months Ended
Jul. 31, 2022	Jul. 31, 2021
Five Tenants [Member] \| Receivables [Member]
Financial instruments and credit risk concentrations (Details) [Line Items]
Concentration risk, percentage	68.90%	65.70%
Two Tenants [Member] \| Revenue [Member]
Financial instruments and credit risk concentrations (Details) [Line Items]
Concentration risk, percentage	31.12%	29.91%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

No definition available.

Name:	mays_ConcentrationRiskPercentages
Namespace Prefix:	mays_
Data Type:	dtr:percentItemType
Balance Type:	na
Period Type:	duration