Interest rate cap and swap contracts (Details) - USD ($)			1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 07, 2018	Dec. 07, 2017	Sep. 29, 2016	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018	Oct. 31, 2018	Apr. 22, 2016	Dec. 26, 2012
Derivative [Line Items]
Mortgages and construction loan payable				$ 342,026,000		$ 342,026,000		$ 350,504,000
Interest rate swap contract assets				438,000		438,000		4,434,000
Unrealized gain (loss) on derivatives				(1,000)	$ 21,000	(160,000)	$ 40,000
Net unrealized gain (loss) on interest rate swap contracts				(2,025,000)	$ 123,000	(5,210,000)	$ 2,661,000	3,113,000
Interest rate swap contract liabilities				1,374,000		1,374,000
Damascus Centre Swap [Member]
Derivative [Line Items]
Interest rate swap contract assets				12,000		12,000
Wayne PSC swap [Member]
Derivative [Line Items]
Interest rate swap contract assets				426,000		426,000
Regency Swap [Member]
Derivative [Line Items]
Interest rate swap contract liabilities				641,000		641,000
Monmouth swap [Member]
Derivative [Line Items]
Interest rate swap contract liabilities				733,000		733,000
Station Place on Monmouth, LLC [Member]
Derivative [Line Items]
Percentage of acquisition		100.00%
Loan amount		$ 12,350,000
Notional amount of interest rate swap		$ 12,350,000
Fixed interest rate		4.35%
Interest rate swap contract assets								460,000
Basis points, interest rate		1.80%
Maturity date of loan		Dec. 15, 2027
Wells Fargo Bank [Member]
Derivative [Line Items]
Loan amount	$ 115,300,000
Aareal Capital Corporation [Member]
Derivative [Line Items]
Loan amount	118,500,000
Available to draw	$ 3,380,000
Basis points, interest rate	2.85%
Maturity date of loan	Feb. 06, 2021
Grande Rotunda LLC [Member]
Derivative [Line Items]
Loan amount				$ 118,500,000		$ 118,500,000
Interest rate cap				3.00%		3.00%
Unrealized gain (loss) on derivatives						$ (160,000)
Interest rate cap asset						$ 0
Basis points, interest rate						2.85%
Grande Rotunda LLC Loan [Member]
Derivative [Line Items]
Loan amount				$ 118,500,000		$ 118,500,000
Notional amount of interest rate swap				$ 121,900,000		$ 121,900,000
Interest rate cap				3.00%		3.00%
Maturity date of cap						Mar. 05, 2020
Wayne PSC, LLC Loan [Member]
Derivative [Line Items]
Refinanced loan amount			$ 24,200,000
Loan amount			$ 25,800,000	$ 24,000,000		$ 24,000,000
Notional amount of interest rate swap				24,000,000		24,000,000
Fixed interest rate			3.625%
Basis points, interest rate			2.20%
People's United Bank [Member]
Derivative [Line Items]
Loan amount				19,500,000		19,500,000
Mortgages and construction loan payable									$ 2,320,000
Notional amount of interest rate swap				$ 19,500,000		$ 19,500,000
People's United Bank [Member] | Tranche One [Member]
Derivative [Line Items]
Loan amount										$ 20,000,000
Fixed interest rate				3.81%		3.81%
Basis points, interest rate						2.10%
Maturity date of loan						Jan. 03, 2023
People's United Bank [Member] | Tranche Two [Member]
Derivative [Line Items]
Fixed interest rate				3.53%		3.53%
Regency Loan [Member]
Derivative [Line Items]
Refinanced loan amount						$ 16,200,000
Loan amount				$ 15,700,000		15,700,000
Notional amount of interest rate swap				$ 15,700,000		$ 15,700,000
Fixed interest rate				3.75%		3.75%
Basis points, interest rate						1.25%
Maturity date of loan						Dec. 15, 2024
Damascus Centre [Member]
Derivative [Line Items]
Interest rate swap contract assets								955,000
Wayne PSC swap [Member]
Derivative [Line Items]
Interest rate swap contract assets								2,452,000
Regency Swap [Member]
Derivative [Line Items]
Interest rate swap contract assets								$ 408,000