Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures (Details Textual)									1 Months Ended									12 Months Ended
	Dec. 06, 2018 USD ($) NumberofUnits	Nov. 09, 2018 USD ($) NumberofUnits	Oct. 29, 2018 USD ($) NumberofUnits	Mar. 03, 2017	Dec. 12, 2016 USD ($) NumberofUnits	Jun. 07, 2016 USD ($)	Apr. 07, 2015 USD ($)	Jan. 12, 2015 USD ($) NumberofUnits	Dec. 28, 2018 USD ($)	Dec. 18, 2018	Nov. 09, 2018 USD ($) NumberofUnits	Oct. 29, 2018 USD ($) NumberofUnits	Dec. 29, 2017 USD ($)	Dec. 22, 2016 USD ($)	Dec. 18, 2015 USD ($) NumberofUnits	Dec. 16, 2015 USD ($)	May 29, 2015 USD ($) NumberofUnits	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018 USD ($) NumberofUnits	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Oct. 06, 2017	Oct. 06, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 01, 2016 USD ($) NumberofUnits	Jan. 06, 2016 USD ($) NumberofUnits	Nov. 20, 2015 USD ($) NumberofUnits	May 20, 2015	Jul. 01, 2014
Equity Method Investment And Joint Venture [Line Items]
Preferred ship Interest Return At Annual Rate																				6.50%
Debt Instrument, Face Amount																$ 39,500,000
Debt Instrument, Description of Variable Rate Basis		LIBOR plus 2.50%
Funded Amount																											$ 7,300,000
Expected Preferred Return On Related Party Debt																					15.00%
Equity Method Investments																					$ 89,033,000	$ 71,145,000
Due from Affiliates																					$ 2,854,000	2,003,000
Debt Instrument, Basis Spread on Variable Rate																					1.75%
Payments to Acquire Equity Method Investments																					$ 17,888,000	20,989,000	$ 26,864,000
Extinguishment of Debt, Amount																38,100,000
Long-term Debt, Maturity Date																					Dec. 31, 2018
Scenario, Forecast [Member]
Equity Method Investment And Joint Venture [Line Items]
Preferred ship Interest Return At Annual Rate																		3.50%	5.00%
15% Percent Preferred Stock [Member]
Equity Method Investment And Joint Venture [Line Items]
Preferred ship Interest Return At Annual Rate		15.00%
BRG Wayforth [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits		150									150										79
Preferred ship Interest Return At Annual Rate																					13.00%
Capital Commitment																					$ 6,500,000
Percentage of Acquire Preferred Equity Interests																					100.00%
Construction Loan		$ 22,300,000									$ 22,300,000
Debt Instrument, Basis Spread on Variable Rate		2.50%
Preferredship Interest Return At Annual Rate Current																					9.00%
Preferredship Interest Return At Annual Rate Accrued																					4.00%
Long-term Debt, Maturity Date		Nov. 09, 2021									Nov. 09, 2021
BRG Wayforth [Member] | Common Class A [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple																														204
North Creek Apartments Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits			259									259
Construction Loan			$ 23,600,000									$ 23,600,000									$ 6,005
Preferredship Interest Return At Annual Rate Current												8.50%
Preferredship Interest Return At Annual Rate Accrued												4.00%
Riverside Apartments Member [Member]
Equity Method Investment And Joint Venture [Line Items]
Debt Instrument, Description of Variable Rate Basis																					LIBOR plus 3.75%
Construction Loan	$ 20,200,000																				$ 1,000,000,000
Debt Instrument, Basis Spread on Variable Rate																					3.75%
Arlo [Member]
Equity Method Investment And Joint Venture [Line Items]
Capital Commitment																												$ 21,300,000
Funded Amount																												6,500,000
Equity Method Investments																					$ 14,000	14,000
BR Flagler Jvllc [Member]
Equity Method Investment And Joint Venture [Line Items]
Capital Commitment																												$ 74,600,000
BRG Whetstone Durham LLC [Member]
Equity Method Investment And Joint Venture [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value																					$ 12,900,000
Percentage of Acquire Preferred Equity Interests																					100.00%
Expected Preferred Return On Related Party Debt																								6.50%
Due from Affiliates																					$ 2,200,000	$ 1,200,000
Alexan CityCentre [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple																															340
Percentage of Number of Units Occupied																					93.00%
Alexan CityCentre [Member] | 15% Percent Preferred Stock [Member]
Equity Method Investment And Joint Venture [Line Items]
Expected Preferred Return On Related Party Debt																					15.00%
Equity Method Investments																					$ 6,500,000
Alexan CityCentre [Member] | 20% Percent Preferred Stock [Member]
Equity Method Investment And Joint Venture [Line Items]
Expected Preferred Return On Related Party Debt																					20.00%
Equity Method Investments																					$ 4,700,000
BRG Southside LLC [Member]
Equity Method Investment And Joint Venture [Line Items]
Percentage of Participation in Profit		50.00%									50.00%
Percentage of Profit Entitled in Occurance of a Default Event		100.00%									100.00%
BRG Southside LLC [Member] | 15% Percent Preferred Stock [Member]
Equity Method Investment And Joint Venture [Line Items]
Effective Annual Preferred Interest Rate Description		(i) 6.5% per annum effective November 9, 2018 through the end of calendar year 2019, (ii) 5.0% per annum for the calendar year 2020, and (iii) 3.5% per annum for the calendar year 2021 and thereafter.
BRG Southside LLC [Member] | Common Class A [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits								270
Leigh House [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits															245
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value															$ 13,300,000
Debt Instrument, Face Amount																					$ 25,200,000
Debt Instrument, Description of Variable Rate Basis																					LIBOR plus 2.65
Percentage of Acquire Preferred Equity Interests																					100.00%
Construction Loan															$ 24,800,000
Expected Preferred Return On Related Party Debt																					20.00%
Percentage of Number of Units Occupied										70.00%											90.00%
Debt Instrument, Basis Spread on Variable Rate																					2.65%
Payments to Acquire Equity Method Investments																					$ 1,400,000
Alexan CityCentre Construction Loan Modification [Member]
Equity Method Investment And Joint Venture [Line Items]
Percentage of Number of Units Occupied																					85.00%
Alexan CityCentre Construction Loan Modification [Member] | Construction Loan Payable [Member]
Equity Method Investment And Joint Venture [Line Items]
Debt Instrument, Description of Variable Rate Basis																					the prime rate plus 0.5% or LIBOR plus 3.00%
Construction Loan						$ 55,100,000
Long-term Construction Loan						55,100,000
Debt Instrument, Periodic Payment, Principal						$ 60,000
BR TC BLVD JV,LLC [Member]
Equity Method Investment And Joint Venture [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value																					$ 11,200,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage																					100.00%
Whetstone Apartment property [Member]
Equity Method Investment And Joint Venture [Line Items]
Debt Instrument, Maturity Date																					Nov. 01, 2023
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate																					3.81%
Percentage Of Prepayment Premium																					1.00%
Secured Debt, Current																					$ 26,000,000				$ 26,500,000
Helios Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits																	282
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value																	$ 19,200,000
Debt Instrument, Face Amount																$ 38,100,000
Debt Instrument, Description of Variable Rate Basis									LIBOR plus 1.75%
Percentage of Acquire Preferred Equity Interests																					100.00%
Construction Loan									$ 39,500,000
Percentage of Number of Units Occupied																					90.00%
Debt Instrument, Basis Spread on Variable Rate									1.75%
Effective Annual Preferred Interest Rate Description		(i) 7.0% per annum effective November 9, 2018 through the end of calendar year 2019, (ii) 6.0% per annum for the calendar year 2020, and (iii) 4.5% per annum for the calendar year 2021 and thereafter.
Fund Amendment Agreement Description											(i) grant the Company a right to compel a sale of the project beginning November 1, 2021 and (ii) grant the Company a 50.0% participation in any profits achieved in a sale after the Company receives its full preferred return and repayment of principal, and Fund III receives full return of its capital contribution. Fund III is obligated to fund its prorata share of future capital calls, absent a default event. If a default event shall occur and is continuing at the time of a sale, BRG Cheshire would be entitled 100% of the profits after Fund III receives full return of its capital contribution. Additionally, the Company agreed to extend the mandatory redemption date of its preferred equity to be reflective of any changes in the loan maturity date as a result of refinancing.
Extinguishment of Debt, Amount									$ 38,100,000
BR Southside , LLC [Member]
Equity Method Investment And Joint Venture [Line Items]
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value								$ 22,800,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage								100.00%
Ground Lease Term								85 years
Alexan Southside Place Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Debt Instrument, Face Amount							$ 31,800,000
Debt Instrument, Description of Variable Rate Basis							based on the base rate plus 1.25% or LIBOR plus 2.25%
Construction Loan							$ 31,700,000
Whetstone Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Percentage of Number of Units Occupied																					97.00%
Arlo [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits																												286
Preferred ship Interest Return At Annual Rate																					0.50%
Cade Boca Raton [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits																											90
Preferred ship Interest Return At Annual Rate																					0.50%
Capital Commitment																										$ 11,200,000
Domain at The One Forty [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits																													299
Preferred ship Interest Return At Annual Rate																					0.50%
Capital Commitment																													$ 20,300,000
Noncontrolling Interest, Description				(i) Fund II substantially redeemed the preferred equity investment held by BRG Domain 1 in BR Domain 1 JV Member for $7.1 million, (ii) BRG Domain 1 maintained a 0.5% common interest in BR Domain 1 JV Member, and (iii) the Company, through BRG Domain 1, provided a mezzanine loan in the amount of $20.3 million to BR Domain 1 JV Member. See Note 6 for further details regarding Domain at The One Forty and the BRG Domain 1 Mezz Loan.
Vickers Village [Member]
Equity Method Investment And Joint Venture [Line Items]
Payments to Acquire Equity Method Investments														$ 8,500,000
Business Acquisition, Percentage of Voting Interests Acquired														80.00%
BR Perimeter JV [Member]
Equity Method Investment And Joint Venture [Line Items]
Preferred ship Interest Return At Annual Rate													0.50%
Capital Commitment													$ 9,800,000
Funded Amount													$ 8,700,000
Noncontrolling Interest, Description													On December 29, 2017, (i) Fund III substantially redeemed the common equity investment held by BRG Vickers in BR Vickers JV Member for $8.7 million, (ii) BRG Vickers maintained a 0.5% common interest in BR Vickers JV Member, and (iii) the Company, through BRG Vickers, provided a mezzanine loan in the amount of $9.8 million to BR Vickers Roswell JV Member. See Note 6 for further details regarding Vickers Village and the BRG Vickers Mezz Loan.
Flagler Village Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits															385
Preferred ship Interest Return At Annual Rate																					0.50%
Capital Commitment															$ 53,600,000
Funded Amount																					$ 26.3
North Creek Apartments Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Preferred ship Interest Return At Annual Rate												12.50%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value			$ 17,900,000
Debt Instrument, Description of Variable Rate Basis																					based on the greater of 6.06% or one-month LIBOR plus 3.75%.
Percentage of Acquire Preferred Equity Interests																					100.00%
Equity Method Investments																					$ 5,900,000
Novel Perimeter Interests formerly known as Crescent Perimeter [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits					320
Preferred ship Interest Return At Annual Rate																					0.50%
Capital Commitment					$ 20,600,000
Funded Amount													$ 15,300,000
Payments to Acquire Equity Method Investments					$ 15,200,000
Riverside Apartments Interests [Member]
Equity Method Investment And Joint Venture [Line Items]
Number of Real Estate Properties, Fee Simple | NumberofUnits	222
Preferred ship Interest Return At Annual Rate																					12.50%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	$ 15,600,000
Percentage of Acquire Preferred Equity Interests																					100.00%
Equity Method Investments																					$ 3,600,000
BR Lake Boone JV and LLC [Member]
Equity Method Investment And Joint Venture [Line Items]
Payments to Acquire Equity Method Investments																					$ 11,900,000