Real Estate Investments - Summary of Major Components of Investments in Multifamily Properties (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Real Estate Properties [Line Items]
Land	$ 231,170	$ 202,347
Buildings and improvements	1,038,797	935,604
Intangible lease assets	2,438	3,049
Construction in progress	1,594	1,881
Furniture, fixtures, and equipment	66,661	61,456
Real estate investment, gross	1,340,660	1,204,337
Accumulated depreciation and amortization	(146,473)	(134,124)
Total Net Operating Real Estate Investments	1,194,187	1,070,213
Accumulated depreciation and amortization	(897)	(897)
Total Net Real Estate Investments	1,211,534	1,087,542
Multifamily Properties
Real Estate Properties [Line Items]
Accumulated depreciation and amortization	(897)	(897)
Total Net Real Estate Investments	1,211,534	1,087,542
Multifamily Properties | Intangible Lease Assets
Real Estate Properties [Line Items]
Total Net Real Estate Investments	1,625	1,424
Multifamily Properties | Land
Real Estate Properties [Line Items]
Total Net Real Estate Investments	237,290	208,467
Multifamily Properties | Buildings and Improvements
Real Estate Properties [Line Items]
Accumulated depreciation and amortization	(736)	(736)
Total Net Real Estate Investments	944,912	850,823
Multifamily Properties | Construction in Progress
Real Estate Properties [Line Items]
Total Net Real Estate Investments	1,594	1,881
Multifamily Properties | Furniture, Fixtures, and Equipment
Real Estate Properties [Line Items]
Accumulated depreciation and amortization	(161)	(161)
Total Net Real Estate Investments	26,113	24,947
Multifamily Properties | Held For Sale Properties
Real Estate Properties [Line Items]
Total Net Operating Real Estate Investments	17,347	17,329
Multifamily Properties | Held For Sale Properties | Land
Real Estate Properties [Line Items]
Total Net Operating Real Estate Investments	6,120	6,120
Multifamily Properties | Held For Sale Properties | Buildings and Improvements
Real Estate Properties [Line Items]
Total Net Operating Real Estate Investments	10,583	10,583
Multifamily Properties | Held For Sale Properties | Furniture, Fixtures, and Equipment
Real Estate Properties [Line Items]
Total Net Operating Real Estate Investments	644	626
Multifamily Properties | Arbors on Forest Ridge
Real Estate Properties [Line Items]
Land	2,330	2,330
Buildings and improvements	11,325	11,319
Furniture, fixtures, and equipment	1,088	1,047
Real estate investment, gross	14,743	14,696
Multifamily Properties | Cutter's Point
Real Estate Properties [Line Items]
Land	3,330	3,330
Buildings and improvements	13,354	13,347
Furniture, fixtures, and equipment	1,400	1,320
Real estate investment, gross	18,084	17,997
Multifamily Properties | Eagle Crest
Real Estate Properties [Line Items]
Land	5,450	5,450
Buildings and improvements	23,039	22,969
Construction in progress	422
Furniture, fixtures, and equipment	1,604	1,563
Real estate investment, gross	30,515	29,982
Multifamily Properties | Silverbrook
Real Estate Properties [Line Items]
Land	4,860	4,860
Buildings and improvements	26,834	26,485
Construction in progress		60
Furniture, fixtures, and equipment	3,321	3,230
Real estate investment, gross	35,015	34,635
Multifamily Properties | Edgewater at Sandy Springs
Real Estate Properties [Line Items]
Land	14,290	14,290
Buildings and improvements	44,572	44,186
Construction in progress		349
Furniture, fixtures, and equipment	5,254	5,083
Real estate investment, gross	64,116	63,908
Multifamily Properties | Beechwood Terrace
Real Estate Properties [Line Items]
Land	1,390	1,390
Buildings and improvements	21,319	21,123
Construction in progress		31
Furniture, fixtures, and equipment	1,789	1,670
Real estate investment, gross	24,498	24,214
Multifamily Properties | Willow Grove
Real Estate Properties [Line Items]
Land	3,940	3,940
Buildings and improvements	10,840	10,829
Furniture, fixtures, and equipment	1,287	1,231
Real estate investment, gross	16,067	16,000
Multifamily Properties | Woodbridge
Real Estate Properties [Line Items]
Land	3,650	3,650
Buildings and improvements	13,141	13,125
Furniture, fixtures, and equipment	1,607	1,536
Real estate investment, gross	18,398	18,311
Multifamily Properties | Abbington Heights
Real Estate Properties [Line Items]
Land	1,770	1,770
Buildings and improvements	17,173	17,140
Furniture, fixtures, and equipment	1,578	1,539
Real estate investment, gross	20,521	20,449
Multifamily Properties | The Summit at Sabal Park
Real Estate Properties [Line Items]
Land	5,770	5,770
Buildings and improvements	13,547	13,447
Construction in progress		43
Furniture, fixtures, and equipment	1,416	1,347
Real estate investment, gross	20,733	20,607
Multifamily Properties | Courtney Cove
Real Estate Properties [Line Items]
Land	5,880	5,880
Buildings and improvements	13,186	13,170
Construction in progress	65
Furniture, fixtures, and equipment	1,315	1,268
Real estate investment, gross	20,446	20,318
Multifamily Properties | Radbourne Lake
Real Estate Properties [Line Items]
Land	2,440	2,440
Buildings and improvements	22,300	22,138
Construction in progress		72
Furniture, fixtures, and equipment	1,584	1,536
Real estate investment, gross	26,324	26,186
Multifamily Properties | Timber Creek
Real Estate Properties [Line Items]
Land	11,260	11,260
Buildings and improvements	13,766	13,582
Furniture, fixtures, and equipment	1,781	1,556
Real estate investment, gross	26,807	26,398
Multifamily Properties | Belmont at Duck Creek
Real Estate Properties [Line Items]
Land	1,910	1,910
Buildings and improvements	17,424	17,397
Furniture, fixtures, and equipment	1,498	1,471
Real estate investment, gross	20,832	20,778
Multifamily Properties | Sabal Palm at Lake Buena Vista
Real Estate Properties [Line Items]
Land	7,580	7,580
Buildings and improvements	41,422	41,336
Furniture, fixtures, and equipment	1,341	1,280
Real estate investment, gross	50,343	50,196
Multifamily Properties | Cornerstone
Real Estate Properties [Line Items]
Land	1,500	1,500
Buildings and improvements	30,522	30,513
Furniture, fixtures, and equipment	2,018	1,885
Real estate investment, gross	34,040	33,898
Multifamily Properties | The Preserve at Terrell Mill
Real Estate Properties [Line Items]
Land	10,170	10,170
Buildings and improvements	49,125	49,091
Construction in progress	6	57
Furniture, fixtures, and equipment	5,190	4,843
Real estate investment, gross	64,491	64,161
Multifamily Properties | The Ashlar
Real Estate Properties [Line Items]
Land	4,090	4,090
Buildings and improvements	12,852	12,845
Furniture, fixtures, and equipment	2,105	2,017
Real estate investment, gross	19,047	18,952
Multifamily Properties | Heatherstone
Real Estate Properties [Line Items]
Land	2,320	2,320
Buildings and improvements	8,137	8,132
Furniture, fixtures, and equipment	1,222	1,199
Real estate investment, gross	11,679	11,651
Multifamily Properties | Versailles
Real Estate Properties [Line Items]
Land	6,720	6,720
Buildings and improvements	21,519	21,513
Furniture, fixtures, and equipment	3,103	3,033
Real estate investment, gross	31,342	31,266
Multifamily Properties | Seasons 704 Apartments
Real Estate Properties [Line Items]
Land	7,480	7,480
Buildings and improvements	14,225	14,223
Furniture, fixtures, and equipment	1,323	1,288
Real estate investment, gross	23,028	22,991
Multifamily Properties | Madera Point
Real Estate Properties [Line Items]
Land	4,920	4,920
Buildings and improvements	17,577	17,570
Furniture, fixtures, and equipment	1,472	1,431
Real estate investment, gross	23,969	23,921
Multifamily Properties | The Pointe at the Foothills
Real Estate Properties [Line Items]
Land	4,840	4,840
Buildings and improvements	47,000	46,998
Furniture, fixtures, and equipment	2,154	2,078
Real estate investment, gross	53,994	53,916
Multifamily Properties | Venue at 8651
Real Estate Properties [Line Items]
Land	2,350	2,350
Buildings and improvements	18,106	18,084
Furniture, fixtures, and equipment	2,597	2,499
Real estate investment, gross	23,053	22,933
Multifamily Properties | Parc500
Real Estate Properties [Line Items]
Land	3,860	3,860
Buildings and improvements	20,780	20,692
Construction in progress		37
Furniture, fixtures, and equipment	2,680	2,600
Real estate investment, gross	27,320	27,189
Multifamily Properties | The Colonnade
Real Estate Properties [Line Items]
Land	8,340	8,340
Buildings and improvements	37,242	37,086
Construction in progress	653	567
Furniture, fixtures, and equipment	1,726	1,604
Real estate investment, gross	47,961	47,597
Multifamily Properties | Old Farm
Real Estate Properties [Line Items]
Land	11,078	11,078
Buildings and improvements	70,496	70,471
Furniture, fixtures, and equipment	1,884	1,800
Real estate investment, gross	83,458	83,349
Multifamily Properties | Stone Creek at Old Farm
Real Estate Properties [Line Items]
Land	3,493	3,493
Buildings and improvements	19,403	19,394
Furniture, fixtures, and equipment	487	467
Real estate investment, gross	23,383	23,354
Multifamily Properties | Hollister Place
Real Estate Properties [Line Items]
Land	2,782	2,782
Buildings and improvements	21,629	21,389
Construction in progress		135
Furniture, fixtures, and equipment	1,601	1,410
Real estate investment, gross	26,012	25,716
Multifamily Properties | Rockledge Apartments
Real Estate Properties [Line Items]
Land	17,451	17,451
Buildings and improvements	95,847	95,484
Construction in progress	29	428
Furniture, fixtures, and equipment	3,690	3,314
Real estate investment, gross	117,017	116,677
Multifamily Properties | Atera Apartments
Real Estate Properties [Line Items]
Land	22,371	22,371
Buildings and improvements	36,664	36,563
Construction in progress	29	86
Furniture, fixtures, and equipment	1,216	1,151
Real estate investment, gross	60,280	60,171
Multifamily Properties | Cedar Pointe
Real Estate Properties [Line Items]
Land	2,372	2,371
Buildings and improvements	23,537	23,458
Intangible lease assets		600
Construction in progress	41	16
Furniture, fixtures, and equipment	561	441
Real estate investment, gross	26,511	26,886
Multifamily Properties | Crestmont Reserve
Real Estate Properties [Line Items]
Land	4,124	4,124
Buildings and improvements	19,653	19,544
Intangible lease assets		687
Construction in progress	105
Furniture, fixtures, and equipment	568	504
Real estate investment, gross	24,450	24,859
Multifamily Properties | Brandywine I & II
Real Estate Properties [Line Items]
Land	6,236	6,237
Buildings and improvements	71,432	70,961
Intangible lease assets		1,762
Construction in progress	244
Furniture, fixtures, and equipment	1,500	1,215
Real estate investment, gross	79,412	80,175
Multifamily Properties | Bella Vista
Real Estate Properties [Line Items]
Land	10,942
Buildings and improvements	36,124
Intangible lease assets	919
Furniture, fixtures, and equipment	640
Real estate investment, gross	48,625
Multifamily Properties | The Enclave
Real Estate Properties [Line Items]
Land	11,046
Buildings and improvements	29,654
Intangible lease assets	769
Furniture, fixtures, and equipment	523
Real estate investment, gross	41,992
Multifamily Properties | Southpoint Reserve at Stoney Creek | Held For Sale Properties
Real Estate Properties [Line Items]
Land	6,120	6,120
Buildings and improvements	11,319	11,319
Furniture, fixtures, and equipment	805	787
Real estate investment, gross	18,244	18,226
Multifamily Properties | Southpoint Reserve at Stoney Creek | Held For Sale Properties | Land
Real Estate Properties [Line Items]
Real estate investment, gross	6,120	6,120
Multifamily Properties | Southpoint Reserve at Stoney Creek | Held For Sale Properties | Buildings and Improvements
Real Estate Properties [Line Items]
Real estate investment, gross	11,319	11,319
Multifamily Properties | Southpoint Reserve at Stoney Creek | Held For Sale Properties | Furniture, Fixtures, and Equipment
Real Estate Properties [Line Items]
Real estate investment, gross	805	787
Multifamily Properties | The Heritage
Real Estate Properties [Line Items]
Land	6,835
Buildings and improvements	34,031
Intangible lease assets	750
Furniture, fixtures, and equipment	538
Real estate investment, gross	42,154
Multifamily Properties | Operating Properties
Real Estate Properties [Line Items]
Real estate investment, gross	1,340,660	1,204,337
Accumulated depreciation and amortization	(146,473)	(134,124)
Total Net Operating Real Estate Investments	1,194,187	1,070,213
Multifamily Properties | Operating Properties | Intangible Lease Assets
Real Estate Properties [Line Items]
Real estate investment, gross	2,438	3,049
Accumulated depreciation and amortization	(813)	(1,625)
Total Net Operating Real Estate Investments	1,625	1,424
Multifamily Properties | Operating Properties | Land
Real Estate Properties [Line Items]
Real estate investment, gross	231,170	202,347
Total Net Operating Real Estate Investments	231,170	202,347
Multifamily Properties | Operating Properties | Buildings and Improvements
Real Estate Properties [Line Items]
Real estate investment, gross	1,038,797	935,604
Accumulated depreciation and amortization	(104,468)	(95,364)
Total Net Operating Real Estate Investments	934,329	840,240
Multifamily Properties | Operating Properties | Construction in Progress
Real Estate Properties [Line Items]
Real estate investment, gross	1,594	1,881
Total Net Operating Real Estate Investments	1,594	1,881
Multifamily Properties | Operating Properties | Furniture, Fixtures, and Equipment
Real Estate Properties [Line Items]
Real estate investment, gross	66,661	61,456
Accumulated depreciation and amortization	(41,192)	(37,135)
Total Net Operating Real Estate Investments	$ 25,469	$ 24,321