DEFERRED CHARGES (Schedule of estimated aggregate amortization expense) (Details)	Jul. 31, 2019 USD ($)
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
2020	$ 291,538
2021	297,985
2022	270,944
2023	257,772
2024	$ 235,093

Amount of amortization expense expected to be recognized during the next fiscal year following the latest fiscal year for deferred charges.

No definition available.

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Amount of amortization expense expected to be recognized during the fifth fiscal year following the latest fiscal year for deferred charges.

No definition available.

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Namespace Prefix:	mays_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of amortization expense expected to be recognized during the fourth fiscal year following the latest fiscal year for deferred charges.

No definition available.

Name:	mays_DeferredChargesAmortizationExpenseYearFour
Namespace Prefix:	mays_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of amortization expense expected to be recognized during the third fiscal year following the latest fiscal year for deferred charges.

No definition available.

Name:	mays_DeferredChargesAmortizationExpenseYearThree
Namespace Prefix:	mays_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of amortization expense expected to be recognized during the second fiscal year following the latest fiscal year for deferred charges.

No definition available.

Name:	mays_DeferredChargesAmortizationExpenseYearTwo
Namespace Prefix:	mays_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

No definition available.

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Data Type:	xbrli:stringItemType
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Period Type:	duration