Notes and Interest Receivable due from Related Party (Details Textual) - USD ($)				1 Months Ended				6 Months Ended
	Mar. 03, 2017	Jan. 06, 2017	Dec. 12, 2016	Mar. 28, 2018	Dec. 29, 2017	Dec. 29, 2016	Dec. 22, 2016	Jun. 30, 2018	Jan. 05, 2017
Related Party Transaction, Interest Rate Description						The loan requires interest-only payments at prime plus 0.625%, subject to a floor of 4.125%. The loan can be prepaid without penalty.
Debt Instrument, Maturity Date, Description	The loan bears interest on a fixed rate of 12.5%, with 9.5% paid currently. Regular monthly payments are interest-only. The loan can be prepaid prior to maturity provided the lender receives a minimum profit and 1% exit fee.
Unaffiliated Lender Transaction Interest Rate Description	The Domain 1 Construction Loan bears interest on a floating basis on the amount drawn based on LIBOR plus 3.25%. Regular monthly payments are interest-only until March 2020, with further payments based on thirty-year amortization. The Domain 1 Construction Loan can be prepaid without penalty.
BR Morehead JV , LLC [Member]
Due from Related Parties						$ 21,300,000
Related Party Transaction, Interest Rate Description						The Company has the right to exercise an option to purchase, at the greater of a 25 basis point discount to fair market value or 15% internal rate of return for Fund II, up to a 100% common membership interest in Arlo JV Member (the mezzanine borrower), which is 99.5% owned by Fund II and which currently holds an approximate 95.0% interest in the Arlo JV and in the Arlo property, subject to certain promote rights of our unaffiliated development partner.
Arlo [Member]
Due from Related Parties								$ 34,500,000
Due from Related Parties, Current						$ 7,300,000
Related Party Transaction, Date								Dec. 29, 2016
Related Party Transaction, Interest Rate Description						The loan bears interest on a fixed rate of 11.5%. Regular monthly payments are interest-only. The loan can be prepaid prior to maturity provided the lender receives a cumulative return of 30% of its loan amount including all principal and interest paid.		The Arlo Construction Loan matures on December 29, 2019, and contains two one-year extension options, subject to certain conditions including a debt service coverage, loan to value ratio and payment of an extension fee. The Arlo Construction Loan bears interest on a floating basis on the amount drawn based on LIBOR plus 3.75%, subject to a minimum of 4.25%. Regular monthly payments are interest-only until September 2019, with further payments based on twenty-five-year amortization. The Arlo Construction Loan can be prepaid without penalty.
Related Party Transaction, Rate								15.00%
Due From Unaffiliated Lender						$ 7,300,000		$ 18,800,000	$ 24,600,000
Unaffiliated Lender Transaction Date						Dec. 29, 2016	Dec. 01, 2020
Development Leased								3.00%
Cade Boca Raton [Member]
Related Party Transaction, Interest Rate Description		The Company has the right to exercise an option to purchase, at the greater of a 25 basis point discount to fair market value or 15% internal rate of return for Fund II, up to a 100% common membership interest in BR Boca JV Member (the mezzanine borrower), which is 99.5% owned by Fund II and which currently holds an approximate 90.0% interest in the Boca JV and in the Cade Boca Raton property, subject to certain promote rights of our unaffiliated development partner.
Due From Unaffiliated Lender						$ 18,700,000		$ 12,300,000
Unaffiliated Lender Transaction Date						Jun. 29, 2019
BRG Boca, LLC [Member]
Due from Related Parties		$ 11,200,000
Related Party Transaction, Date		Jan. 06, 2020
Domain 1 property Owner [Member]
Due from Related Parties	$ 20,300,000
BRG Domain 1 [Member]
Related Party Transaction, Interest Rate Description	The Company has the right to exercise an option to purchase, at the greater of a 25 basis point discount to fair market value or 15% internal rate of return for Fund II, up to a 100% common membership interest in BR Domain 1 JV Member (the mezzanine borrower), which is 99.5% owned by Fund II and which currently holds an approximate 95.0% interest in the Domain 1 JV and in the Domain at The One Forty property, subject to certain promote rights of our unaffiliated development partner.
Unaffiliated Lender Transaction Interest Rate Description	The Company has the right to exercise an option to purchase, at the greater of a 25 basis point discount to fair market value or 15% internal rate of return for Fund II, up to a 100% common membership interest in BR Domain 1 JV Member (the mezzanine borrower), which is 99.5% owned by Fund II and which currently holds an approximate 95.0% interest in the Domain 1 JV and in the Domain 1 property, subject to certain promote rights of our unaffiliated development partner.
BR Flagler JV,LLC [Member]
Due from Related Parties				$ 74,600,000	$ 53,600,000
Related Party Transaction, Date					Dec. 29, 2022
Percentage Of Loan Secured				97.40%
Flagler Village Property Owner [Member]
Due from Related Parties, Current								1,010
Related Party Transaction, Date				Mar. 28, 2022
Related Party Transaction, Interest Rate Description				The loan bears interest at the greater of 5.0% or a rate of LIBOR plus 3.85%, with interest only payments until March 28, 2022, with future payments after extension based on 30-year amortization. The loan can be prepaid subject to payment of a make-whole premium and exit fee.
Due From Unaffiliated Lender				$ 70,400,000
Novel Perimeter [Member]
Due From Unaffiliated Lender			$ 44,700,000					22,400,000
Unaffiliated Lender Transaction Interest Rate Description			The loan bears interest at a rate of LIBOR plus 3.00%, with interest only payments until December 12, 2020, with future payments based on 30-year amortization. The loan can be prepaid without penalty.
Unaffiliated Lender Transaction Date			Dec. 12, 2020
Vickers Historic Roswell [Member]
Due From Unaffiliated Lender							$ 18,000,000	$ 14,900,000
Unaffiliated Lender Transaction Interest Rate Description							The loan bears interest at a rate of LIBOR plus 3.00%, with interest only payments until December 1, 2018, with future payments based on 25-year amortization. The loan can be prepaid without penalty.
Unaffiliated Lender Transaction Date							Dec. 01, 2018
Development Leased								9.00%
BR Perimeter JV,LLC [Member]
Due from Related Parties					$ 20,600,000
Related Party Transaction, Date					Dec. 29, 2021
BR Vickers Roswell JV, LLC [Member]
Due from Related Parties					$ 9,800,000
Related Party Transaction, Date					Dec. 29, 2020
BRG Flagler Mezz Loan [Member]
Related Party Transaction, Date				Mar. 28, 2023
Domain at The One Forty [Member]
Due From Unaffiliated Lender	$ 30,300,000							$ 14,300,000
Unaffiliated Lender Transaction Date								Mar. 03, 2020
Development Leased								3.00%
Property Owner One Forty [Member]
Due From Unaffiliated Lender	$ 6,400,000							$ 6,400,000