Mortgage Notes Payable, Net - Summary of Mortgage Notes Payable (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Outstanding borrowings		$ 552,074
Deferred Financing Costs, net		(4,399)
Carrying Value		547,875	$ 573,642
Mortgage notes payable
Debt Instrument [Line Items]
Outstanding borrowings		552,074	578,826
Premium, net		(200)	(313)
Deferred Financing Costs, net		(4,399)	(5,497)
Carrying Value		547,875	573,642
Mortgage notes payable | Overton Trails Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings			29,841
Deferred Financing Costs, net			(246)
Carrying Value			29,595
Mortgage notes payable | Uptown Buckhead
Debt Instrument [Line Items]
Outstanding borrowings		19,264	19,651
Deferred Financing Costs, net		(178)	(213)
Carrying Value		$ 19,086	19,438
Maturity Date	[1],[2],[3]	Jul. 01, 2025
Annual Interest Rate	[1],[2],[3]	3.98%
Average Monthly Debt Service	[1],[2],[3]	$ 104
Average Monthly Escrow	[1],[2],[3]	$ 63
Mortgage notes payable | Uptown Buckhead | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[1],[2],[3]	2.22%
Mortgage notes payable | Crosstown at Chapel Hill
Debt Instrument [Line Items]
Outstanding borrowings		$ 42,650	42,650
Deferred Financing Costs, net		(325)	(386)
Carrying Value		$ 42,325	42,264
Maturity Date	[2],[3],[4],[5]	Jul. 01, 2025
Annual Interest Rate	[2],[3],[4],[5]	3.53%
Average Monthly Debt Service	[2],[3],[4],[5]	$ 142
Average Monthly Escrow	[2],[3],[4],[5]	$ 279
Mortgage notes payable | Crosstown at Chapel Hill | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4],[5]	1.77%
Mortgage notes payable | The Brookwood - Key Bank
Debt Instrument [Line Items]
Outstanding borrowings		$ 17,063	17,477
Premium, net		(186)	(291)
Deferred Financing Costs, net		(88)	(137)
Carrying Value		$ 17,161	17,631
Maturity Date	[6],[7]	Nov. 01, 2021
Annual Interest Rate	[6],[7]	4.73%
Average Monthly Debt Service	[6],[7]	$ 104
Average Monthly Escrow	[6],[7]	54
Mortgage notes payable | The Brookwood - Capital One
Debt Instrument [Line Items]
Outstanding borrowings		2,566	2,613
Premium, net		(14)	(22)
Deferred Financing Costs, net		(15)	(24)
Carrying Value		$ 2,565	2,611
Maturity Date	[6],[7]	Nov. 01, 2021
Annual Interest Rate	[6],[7]	5.40%
Average Monthly Debt Service	[6],[7]	$ 16
Mortgage notes payable | Adair off Addison and Adair off Addison Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings		33,210	24,629
Deferred Financing Costs, net		(380)	(233)
Carrying Value		$ 32,830	24,396
Maturity Date	[2],[3],[8]	May 01, 2026
Annual Interest Rate	[2],[3],[8]	3.40%
Average Monthly Debt Service	[2],[3],[8]	$ 107
Average Monthly Escrow	[2],[3],[8]	$ 81
Mortgage notes payable | Adair off Addison and Adair off Addison Apartment Homes | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[8]	1.64%
Mortgage notes payable | 1000 Spalding Crossing
Debt Instrument [Line Items]
Outstanding borrowings		$ 23,737	24,195
Deferred Financing Costs, net		(113)	(171)
Carrying Value		$ 23,624	24,024
Maturity Date	[4],[7]	Jan. 01, 2022
Annual Interest Rate	[4],[7]	3.88%
Average Monthly Debt Service	[4],[7]	$ 116
Average Monthly Escrow	[4],[7]	51
Mortgage notes payable | Ravina Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings		26,241	26,951
Deferred Financing Costs, net		(165)	(239)
Carrying Value		$ 26,076	26,712
Maturity Date	[6],[7]	May 01, 2022
Annual Interest Rate	[6],[7]	3.76%
Average Monthly Debt Service	[6],[7]	$ 144
Average Monthly Escrow	[6],[7]	144
Mortgage notes payable | Verdant Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings		36,913	37,300
Deferred Financing Costs, net		(178)	(233)
Carrying Value		$ 36,735	37,067
Maturity Date	[4],[7]	May 01, 2023
Annual Interest Rate	[4],[7]	3.89%
Average Monthly Debt Service	[4],[7]	$ 176
Average Monthly Escrow	[4],[7]	37
Mortgage notes payable | Arcadia Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings		39,782	40,200
Deferred Financing Costs, net		(195)	(256)
Carrying Value		$ 39,587	39,944
Maturity Date	[4],[7]	May 01, 2023
Annual Interest Rate	[4],[7]	3.89%
Average Monthly Debt Service	[4],[7]	$ 189
Average Monthly Escrow	[4],[7]	35
Mortgage notes payable | Grand Reserve
Debt Instrument [Line Items]
Outstanding borrowings		47,845	47,845
Deferred Financing Costs, net		(539)	(606)
Carrying Value		$ 47,306	47,239
Maturity Date	[2],[3],[4],[5]	May 01, 2028
Annual Interest Rate	[2],[3],[4],[5]	3.48%
Average Monthly Debt Service	[2],[3],[4],[5]	$ 157
Average Monthly Escrow	[2],[3],[4],[5]	$ 90
Mortgage notes payable | Grand Reserve | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4],[5]	1.72%
Mortgage notes payable | Montclair Terrace
Debt Instrument [Line Items]
Outstanding borrowings		$ 19,958	20,312
Deferred Financing Costs, net		(182)	(234)
Carrying Value		$ 19,776	20,078
Maturity Date	[2],[3],[6]	Jun. 01, 2023
Annual Interest Rate	[2],[3],[6]	4.21%
Average Monthly Debt Service	[2],[3],[6]	$ 107
Average Monthly Escrow	[2],[3],[6]	$ 102
Mortgage notes payable | Montclair Terrace | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[6]	2.45%
Mortgage notes payable | 81 Fifty at West Hills Apartment Homes
Debt Instrument [Line Items]
Outstanding borrowings		$ 51,833	52,645
Deferred Financing Costs, net		(368)	(477)
Carrying Value		$ 51,465	52,168
Maturity Date	[2],[3],[4]	Jul. 01, 2023
Annual Interest Rate	[2],[3],[4]	4.12%
Average Monthly Debt Service	[2],[3],[4]	$ 269
Average Monthly Escrow	[2],[3],[4]	$ 58
Mortgage notes payable | 81 Fifty at West Hills Apartment Homes | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	2.36%
Mortgage notes payable | The Palmer at Las Colinas
Debt Instrument [Line Items]
Outstanding borrowings		$ 45,700	45,700
Deferred Financing Costs, net		(437)	(506)
Carrying Value		$ 45,263	45,194
Maturity Date	[2],[3],[4]	Sep. 01, 2026
Annual Interest Rate	[2],[3],[4]	3.87%
Average Monthly Debt Service	[2],[3],[4]	$ 166
Average Monthly Escrow	[2],[3],[4]	$ 159
Mortgage notes payable | The Palmer at Las Colinas | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	2.11%
Mortgage notes payable | Windbrooke Crossing
Debt Instrument [Line Items]
Outstanding borrowings		$ 37,222	37,788
Deferred Financing Costs, net		(272)	(343)
Carrying Value		$ 36,950	37,445
Maturity Date	[2],[3],[4]	Jan. 01, 2024
Annual Interest Rate	[2],[3],[4]	4.45%
Average Monthly Debt Service	[2],[3],[4]	$ 201
Average Monthly Escrow	[2],[3],[4]	$ 65
Mortgage notes payable | Windbrooke Crossing | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	2.69%
Mortgage notes payable | Woods of Burnsville
Debt Instrument [Line Items]
Outstanding borrowings		$ 37,744	38,250
Deferred Financing Costs, net		(355)	(445)
Carrying Value		$ 37,389	37,805
Maturity Date	[2],[3],[4]	Feb. 01, 2024
Annual Interest Rate	[2],[3],[4]	3.89%
Average Monthly Debt Service	[2],[3],[4]	$ 190
Average Monthly Escrow	[2],[3],[4]	$ 84
Mortgage notes payable | Woods of Burnsville | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	2.13%
Mortgage notes payable | Indigo Creek
Debt Instrument [Line Items]
Outstanding borrowings		$ 40,402	40,789
Deferred Financing Costs, net		(320)	(397)
Carrying Value		$ 40,082	40,392
Maturity Date	[2],[3],[4]	May 01, 2024
Annual Interest Rate	[2],[3],[4]	3.69%
Average Monthly Debt Service	[2],[3],[4]	$ 199
Average Monthly Escrow	[2],[3],[4]	$ 52
Mortgage notes payable | Indigo Creek | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	1.93%
Mortgage notes payable | Martin's Point
Debt Instrument [Line Items]
Outstanding borrowings		$ 29,944	29,990
Deferred Financing Costs, net		(289)	(351)
Carrying Value		$ 29,655	$ 29,639
Maturity Date	[2],[3],[4]	Nov. 01, 2024
Annual Interest Rate	[2],[3],[4]	3.62%
Average Monthly Debt Service	[2],[3],[4]	$ 149
Average Monthly Escrow	[2],[3],[4]	$ 76
Mortgage notes payable | Martin's Point | LIBOR
Debt Instrument [Line Items]
Margin over LIBOR	[2],[3],[4]	1.86%

[1] Monthly fixed principal plus interest payment required

[2] Variable rate based on one-month LIBOR of 1.76250% (as of December 31, 2019) plus a fixed margin

[3] Variable rate hedged with interest rate cap cash flow hedge

[4] Monthly interest-only payment currently required

[5] Originated during the year ended December 31, 2018 through refinancing

[6] Fixed monthly payment of principal and interest payment required

[7] Fixed rate

[8] Originated during the year ended December 31, 2019 through refinancing