Interest rate swap contracts (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
	Sep. 29, 2016	Jan. 31, 2017	Jan. 31, 2016	Oct. 31, 2016	Apr. 22, 2016	Dec. 26, 2012
Mortgages and construction loan payable		$ 330,080,000		$ 329,719,000
Interest rate swap contract assets		1,593,000		91,000
Interest rate swap contract liabilities		538,000		1,882,000
Damascus Centre Swap [Member]
Interest rate swap contract assets		216,000
Unrealized gain (loss) on derivatives			$ 698,000	725,000
Interest rate swap contract liabilities			453,000	521,000
Regency Swap [Member]
Interest rate swap contract liabilities		538,000	$ 1,311,000	1,361,000
Wayne PSC swap [Member]
Interest rate swap contract assets		1,377,000		$ 91,000
Wayne PSC, LLC Loan [Member]
Refinanced loan amount	$ 24,200,000
Loan amount		25,600,000
Description of loan amendment terms	In order to minimize interest rate volatility during the term of the loan, Wayne PSC, LLC entered into an interest rate swap agreement that, in effect, converted the floating interest rate to a fixed interest rate of 3.625% over the term of the loan. This refinancing resulted in: (i) a reduction in interest rate from 6.04% to 3.625% and (ii) net refinancing proceeds of approximately $1 million that were distributed to the partners in Wayne PSC, LLC with FREIT receiving $0.4 million based on its 40% membership interest in Wayne PSC, LLC.
Notional amount of interest rate swap		25,600,000
Fixed interest rate	3.625%
Unrealized gain (loss) on derivatives		2,846,000
Basis points, interest rate	2.20%
Maturity date of loan	Oct. 01, 2026
People's United Bank [Member]
Mortgages and construction loan payable					$ 2,320,000
Notional amount of interest rate swap		$ 20,800,000
People's United Bank [Member] | Tranche One [Member]
Loan amount						$ 20,000,000
Fixed interest rate		3.81%
Basis points, interest rate		2.10%
Maturity date of loan		Jan. 03, 2023
People's United Bank [Member] | Tranche Two [Member]
Loan amount					2,320,000
Fixed interest rate		3.53%
Basis points, interest rate		2.10%
Amount of loan readily available					470,000
Amount of loan held in escrow					$ 1,850,000
Maturity date of loan		Jan. 03, 2023
Provident Bank [Member]
Loan amount		$ 16,200,000
Notional amount of interest rate swap		$ 16,200,000
Fixed interest rate		3.75%
Basis points, interest rate		1.25%
Maturity date of loan		Dec. 15, 2024