Notes and Interest Receivable due from Related Parties (Details Textual) - USD ($)					1 Months Ended						12 Months Ended
	Nov. 09, 2018	Mar. 03, 2017	Jan. 06, 2017	Dec. 12, 2016	Aug. 13, 2018	Mar. 28, 2018	Dec. 29, 2017	Mar. 31, 2017	Dec. 29, 2016	Dec. 22, 2016	Dec. 31, 2018	Jan. 23, 2019	Dec. 31, 2017	Jan. 05, 2017
Due from Related Parties												$ 800,000
Related Party Transaction, Date											Dec. 29, 2016
Related Party Transaction, Interest Rate Description									The Boca Construction Loan requires interest-only payments at prime plus 0.625%, subject to a floor of 4.125% and can be prepaid without penalty.
Related Party Transaction, Rate							15.00%
Due From Unaffiliated Lender				$ 44,700,000
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.		The Novel Perimeter Construction Loan bears interest at a rate of LIBOR plus 3.00%, with interest only payments until December 12, 2020 and future payments based on thirty-year amortization. The Novel Perimeter Construction Loan can be prepaid without penalty.
Unaffiliated Lender Transaction Date									Dec. 29, 2016
Description Of Exercise Of Options					the Company received the right to exercise an option to purchase, at the greater of a 10 basis point discount to fair market value or 15% internal rate of return for Fund III, up to a 100% common membership interest in BR Vickers JV Member.
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, 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		$ 29,100,000			$ 24,600,000
Development Leased											37.00%
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		$ 16,900,000
Unaffiliated Lender Transaction Date									Jun. 29, 2019
Development Leased											8.00%
BRG Boca, LLC [Member]
Due from Related Parties			$ 11,200,000
Related Party Transaction, Date			Jan. 05, 2020
Capital Call amount	$ 500,000
Domain 1 property Owner [Member]
Due from Related Parties		$ 20,300,000
Development Leased											34.00%
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 at The One Forty 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											$ 1,042
Related Party Transaction, Interest Rate Description						The Flagler Construction 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 and future payments after extension based on thirty-year amortization. The Flagler Construction 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				$ 39,200,000
Unaffiliated Lender Transaction Date				Dec. 12, 2020
Development Leased											22.00%
Vickers Historic Roswell [Member]
Due From Unaffiliated Lender										$ 18,000,000	$ 17,400,000
Unaffiliated Lender Transaction Interest Rate Description										The Vickers Construction Loan matures December 1, 2020 and bears interest at a rate of LIBOR plus 3.00%, with interest only payments until December 1, 2018 and future payments based on twenty-five-year amortization. The Vickers Construction Loan can be prepaid without penalty.
Development Leased											41.00%
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
Additional Capital Contribution					$ 300,000						$ 300,000
Equity Method Investment, Ownership Percentage					99.50%						80.00%
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									$ 26,300,000
Property Owner One Forty [Member]
Due From Unaffiliated Lender		$ 6,400,000									6,400,000
BR Boca JV [Member]
Description Of Exercise Of Options	the Company received an additional 2.5 basis point discount purchase option and has the right to exercise an option to purchase, at the greater of a 27.5 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.
BR Vickers JV [Member]
Description Of Exercise Of Options	the Company received an additional 2.5 basis point discount purchase option and has the right to exercise an option to purchase, at the greater of a 12.5 basis point discount to fair market value or 15% internal rate of return for Fund III, up to a 100% common membership interest in BR Vickers JV Member.
Capital Call amount	$ 300,000										$ 0.3