SELF-STORAGE INVESTMENT PORTFOLIO (Schedule of Investments) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Feb. 20, 2018	Feb. 02, 2018	Jan. 10, 2018	Aug. 09, 2017	Aug. 08, 2017	Feb. 02, 2017	May 27, 2016
Schedule of Investments [Line Items]
Investment Commitment		$ 673,090	$ 523,821
Funded Investment		365,479	213,069	$ 24,754			$ 9,139
Development property investments, Fair Value		302,245	228,233
Bridge loan investments, Fair Value		79,581
Operating property loans, Fair Value		5,862	5,938
Total investments		387,688	234,171
Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		365,479	213,069
Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		307,611	310,752
Atlanta 1 [Member]
Schedule of Investments [Line Items]
Funded Investment					$ 8,084
Atlanta 2 [Member]
Schedule of Investments [Line Items]
Funded Investment					$ 5,766
Pittsburgh [Member]
Schedule of Investments [Line Items]
Funded Investment				$ 4,938
Jacksonville 1 [Member]
Schedule of Investments [Line Items]
Funded Investment						$ 5,966
Los Angeles 2 [Member]
Schedule of Investments [Line Items]
Total project cost of an investment		$ 29,500
Percentage of financing provided by a traditional bank		65.00%
Percentage of Financing not offered by the bank		35.00%
Preferred return on investment		6.90%
Ownership percentage on remaining 35% after bank's financing		90.00%
Transaction fee, percentage of total project cost		1.00%
Profits interest, percentage of total project cost		49.90%
Development Property Investments [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 583,784	517,839
Development property investments, Fair Value		302,245	228,233
Equity method investment percentage of additional equity acquired	50.10%
Development Property Investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		280,626	207,089
Development Property Investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		303,158	310,750
Development Property Investments [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Commitment		566,051	500,106
Development property investments, Fair Value		$ 286,390	$ 215,860
Percentage of completion of construction		40.00%	40.00%
Ownership percentage on remaining 35% after bank's financing		49.90%
Development Property Investments [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		$ 264,660	$ 194,597
Development Property Investments [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		301,391	305,509
Development Property Investments [Member] | Construction Loans [Member]
Schedule of Investments [Line Items]
Investment Commitment		17,733	17,733
Development property investments, Fair Value		15,855	12,373
Development Property Investments [Member] | Construction Loans [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		15,966	12,492
Development Property Investments [Member] | Construction Loans [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 1,767	$ 5,241
Development Property Investments [Member] | Orlando 1 [Member]
Schedule of Investments [Line Items]
Ownership percentage on remaining 35% after bank's financing									49.90%
Development Property Investments [Member] | Atlanta 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date			6/10/2015
Investment Commitment			$ 8,132
Development property investments, Fair Value			10,741
Development Property Investments [Member] | Atlanta 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment			8,086
Development Property Investments [Member] | Atlanta 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment			$ 46
Development Property Investments [Member] | Tampa 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/19/2015	6/19/2015
Investment Commitment		$ 5,369	$ 5,369
Development property investments, Fair Value		5,931	6,012
Development Property Investments [Member] | Tampa 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,285	5,285
Development Property Investments [Member] | Tampa 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 84	$ 84
Development Property Investments [Member] | Atlanta 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date			6/26/2015
Investment Commitment			$ 6,050
Development property investments, Fair Value			8,631
Development Property Investments [Member] | Atlanta 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment			5,769
Development Property Investments [Member] | Atlanta 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment			$ 281
Development Property Investments [Member] | Charlotte 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/29/2015	6/29/2015
Investment Commitment		$ 7,624	$ 7,624
Development property investments, Fair Value		9,556	10,363
Development Property Investments [Member] | Charlotte 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		7,357	7,251
Development Property Investments [Member] | Charlotte 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 267	$ 373
Development Property Investments [Member] | Milwaukee [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		7/2/2015	7/2/2015
Investment Commitment		$ 7,650	$ 7,650
Development property investments, Fair Value		9,241	8,994
Development Property Investments [Member] | Milwaukee [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		7,641	7,512
Development Property Investments [Member] | Milwaukee [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 9	$ 138
Development Property Investments [Member] | New Haven [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		7/31/2015	7/31/2015
Investment Commitment		$ 6,930	$ 6,930
Development property investments, Fair Value		8,342	8,231
Development Property Investments [Member] | New Haven [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		6,600	6,524
Development Property Investments [Member] | New Haven [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 330	$ 406
Development Property Investments [Member] | Pittsburgh [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date			8/10/2015
Investment Commitment			$ 5,266
Development property investments, Fair Value			6,774
Development Property Investments [Member] | Pittsburgh [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment			4,798
Development Property Investments [Member] | Pittsburgh [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment			$ 468
Development Property Investments [Member] | Raleigh [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		8/14/2015	8/14/2015
Investment Commitment		$ 8,792	$ 8,792
Development property investments, Fair Value		8,442	5,889
Development Property Investments [Member] | Raleigh [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		8,176	5,550
Development Property Investments [Member] | Raleigh [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 616	$ 3,242
Development Property Investments [Member] | Jacksonville 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date			9/30/2015
Investment Commitment			$ 6,445
Development property investments, Fair Value			8,913
Development Property Investments [Member] | Jacksonville 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment			5,988
Development Property Investments [Member] | Jacksonville 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment			$ 457
Development Property Investments [Member] | Austin [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		10/27/2015	10/27/2015
Investment Commitment		$ 8,658	$ 8,658
Development property investments, Fair Value		8,600	8,782
Development Property Investments [Member] | Austin [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		7,551	7,297
Development Property Investments [Member] | Austin [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 1,107	$ 1,361
Development Property Investments [Member] | Charlotte 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		9/20/2016	9/20/2016
Investment Commitment		$ 12,888	$ 12,888
Development property investments, Fair Value		10,660	5,686
Development Property Investments [Member] | Charlotte 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		9,497	5,453
Development Property Investments [Member] | Charlotte 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,391	$ 7,435
Development Property Investments [Member] | Orlando 2 [Member]
Schedule of Investments [Line Items]
Ownership percentage on remaining 35% after bank's financing								49.90%
Development Property Investments [Member] | Jacksonville 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		11/17/2016	11/17/2016
Investment Commitment		$ 7,530	$ 7,530
Development property investments, Fair Value		8,512	5,818
Development Property Investments [Member] | Jacksonville 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		6,890	4,971
Development Property Investments [Member] | Jacksonville 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 640	$ 2,559
Development Property Investments [Member] | New York City 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		1/4/2017	1/4/2017
Investment Commitment		$ 16,117	$ 16,117
Development property investments, Fair Value		20,934	18,892
Development Property Investments [Member] | New York City 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		16,056	14,914
Development Property Investments [Member] | New York City 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 61	$ 1,203
Development Property Investments [Member] | Atlanta 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		1/18/2017	1/18/2017
Investment Commitment		$ 14,115	$ 14,115
Development property investments, Fair Value		4,028	2,236
Development Property Investments [Member] | Atlanta 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,212	2,393
Development Property Investments [Member] | Atlanta 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 9,903	$ 11,722
Development Property Investments [Member] | Atlanta 4 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		1/31/2017	1/31/2017
Investment Commitment		$ 13,678	$ 13,678
Development property investments, Fair Value		11,995	7,147
Development Property Investments [Member] | Atlanta 4 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		10,206	7,040
Development Property Investments [Member] | Atlanta 4 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,472	$ 6,638
Development Property Investments [Member] | Orlando 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		2/24/2017	2/24/2017
Investment Commitment		$ 8,056	$ 8,056
Development property investments, Fair Value		7,004	3,335
Development Property Investments [Member] | Orlando 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,961	3,144
Development Property Investments [Member] | Orlando 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 2,095	$ 4,912
Development Property Investments [Member] | New Orleans [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		2/24/2017	2/24/2017
Investment Commitment		$ 12,549	$ 12,549
Development property investments, Fair Value		4,454	553
Development Property Investments [Member] | New Orleans [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,411	677
Development Property Investments [Member] | New Orleans [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 8,138	$ 11,872
Development Property Investments [Member] | Atlanta 5 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		2/27/2017	2/27/2017
Investment Commitment		$ 17,492	$ 17,492
Development property investments, Fair Value		8,179	4,739
Development Property Investments [Member] | Atlanta 5 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		8,262	4,971
Development Property Investments [Member] | Atlanta 5 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 9,230	$ 12,521
Development Property Investments [Member] | Fort Lauderdale [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/1/2017	3/1/2017
Investment Commitment		$ 9,952	$ 9,952
Development property investments, Fair Value		4,045	1,043
Development Property Investments [Member] | Fort Lauderdale [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		3,934	1,128
Development Property Investments [Member] | Fort Lauderdale [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,018	$ 8,824
Development Property Investments [Member] | Houston [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/1/2017	3/1/2017
Investment Commitment		$ 13,630	$ 13,630
Development property investments, Fair Value		6,388	3,547
Development Property Investments [Member] | Houston [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		6,079	3,633
Development Property Investments [Member] | Houston [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 7,551	$ 9,997
Development Property Investments [Member] | Louisville 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		4/14/2017	4/14/2017
Investment Commitment		$ 8,523	$ 8,523
Development property investments, Fair Value		6,049	3,083
Development Property Investments [Member] | Louisville 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,255	2,932
Development Property Investments [Member] | Louisville 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,268	$ 5,591
Development Property Investments [Member] | Denver 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		4/20/2017	4/20/2017
Investment Commitment		$ 9,806	$ 9,806
Development property investments, Fair Value		3,587	1,849
Development Property Investments [Member] | Denver 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		3,706	1,940
Development Property Investments [Member] | Denver 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,100	$ 7,866
Development Property Investments [Member] | Denver 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		4/20/2017	4/20/2017
Investment Commitment		$ 11,164	$ 11,164
Development property investments, Fair Value		9,718	5,849
Development Property Investments [Member] | Denver 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		8,173	5,442
Development Property Investments [Member] | Denver 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 2,991	$ 5,722
Development Property Investments [Member] | Atlanta 6 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/2/2017	5/2/2017
Investment Commitment		$ 12,543	$ 12,543
Development property investments, Fair Value		9,863	4,262
Development Property Investments [Member] | Atlanta 6 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		8,658	4,344
Development Property Investments [Member] | Atlanta 6 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,885	$ 8,199
Development Property Investments [Member] | Tampa 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/2/2017	5/2/2017
Investment Commitment		$ 8,091	$ 8,091
Development property investments, Fair Value		1,991	1,010
Development Property Investments [Member] | Tampa 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,070	1,086
Development Property Investments [Member] | Tampa 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,021	$ 7,005
Development Property Investments [Member] | Tampa 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/19/2017	5/19/2017
Investment Commitment		$ 9,224	$ 9,224
Development property investments, Fair Value		4,787	1,335
Development Property Investments [Member] | Tampa 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,379	1,422
Development Property Investments [Member] | Tampa 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 4,845	$ 7,802
Development Property Investments [Member] | Tampa 4 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/12/2017	6/12/2017
Investment Commitment		$ 10,266	$ 10,266
Development property investments, Fair Value		7,187	1,752
Development Property Investments [Member] | Tampa 4 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		6,127	1,847
Development Property Investments [Member] | Tampa 4 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 4,139	$ 8,419
Development Property Investments [Member] | Baltimore [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/19/2017	6/19/2017
Investment Commitment		$ 10,775	$ 10,775
Development property investments, Fair Value		5,667	3,115
Development Property Investments [Member] | Baltimore [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,584	3,315
Development Property Investments [Member] | Baltimore [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 5,191	$ 7,460
Development Property Investments [Member] | Knoxville [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/28/2017	6/28/2017
Investment Commitment		$ 9,115	$ 9,115
Development property investments, Fair Value		4,605	1,265
Development Property Investments [Member] | Knoxville [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,367	1,351
Development Property Investments [Member] | Knoxville [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 4,748	$ 7,764
Development Property Investments [Member] | Boston 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/29/2017	6/29/2017
Investment Commitment		$ 14,103	$ 14,103
Development property investments, Fair Value		11,786	4,914
Development Property Investments [Member] | Boston 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		10,801	4,978
Development Property Investments [Member] | Boston 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,302	$ 9,125
Development Property Investments [Member] | New York City 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/30/2017	6/30/2017
Investment Commitment		$ 26,482	$ 26,482
Development property investments, Fair Value		19,759	17,576
Development Property Investments [Member] | New York City 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		20,356	18,042
Development Property Investments [Member] | New York City 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,126	$ 8,440
Development Property Investments [Member] | Jacksonville 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		7/27/2017	7/27/2017
Investment Commitment		$ 8,096	$ 8,096
Development property investments, Fair Value		4,993	1,053
Development Property Investments [Member] | Jacksonville 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,411	1,134
Development Property Investments [Member] | Jacksonville 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 3,685	$ 6,962
Development Property Investments [Member] | Orlando 4 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		8/30/2017	8/30/2017
Investment Commitment		$ 9,037	$ 9,037
Development property investments, Fair Value		2,561	1,960
Development Property Investments [Member] | Orlando 4 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,661	2,059
Development Property Investments [Member] | Orlando 4 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,376	$ 6,978
Development Property Investments [Member] | Los Angeles [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		9/14/2017	9/14/2017
Investment Commitment		$ 28,750	$ 28,750
Development property investments, Fair Value		7,672	7,398
Development Property Investments [Member] | Los Angeles [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		7,923	7,533
Development Property Investments [Member] | Los Angeles [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 20,827	$ 21,217
Development Property Investments [Member] | Miami 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		9/14/2017	9/14/2017
Investment Commitment		$ 14,657	$ 14,657
Development property investments, Fair Value		6,785	5,725
Development Property Investments [Member] | Miami 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		6,942	5,862
Development Property Investments [Member] | Miami 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 7,715	$ 8,795
Development Property Investments [Member] | Louisville 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		9/28/2017	9/28/2017
Investment Commitment		$ 9,940	$ 9,940
Development property investments, Fair Value		5,861	1,762
Development Property Investments [Member] | Louisville 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,316	1,864
Development Property Investments [Member] | Louisville 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 4,624	$ 8,076
Development Property Investments [Member] | Miami 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		10/12/2017	10/12/2017
Investment Commitment		$ 9,459	$ 9,459
Development property investments, Fair Value		818	820
Development Property Investments [Member] | Miami 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		1,062	1,014
Development Property Investments [Member] | Miami 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 8,397	$ 8,445
Development Property Investments [Member] | New York City 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		10/30/2017	10/30/2017
Investment Commitment		$ 14,701	$ 14,701
Development property investments, Fair Value		3,384	2,294
Development Property Investments [Member] | New York City 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		3,712	2,595
Development Property Investments [Member] | New York City 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 10,989	$ 12,106
Development Property Investments [Member] | Miami 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		11/16/2017	11/16/2017
Investment Commitment		$ 20,168	$ 20,168
Development property investments, Fair Value		3,740	3,099
Development Property Investments [Member] | Miami 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,309	3,508
Development Property Investments [Member] | Miami 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 15,859	$ 16,660
Development Property Investments [Member] | Minneapolis 1 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		11/21/2017	11/21/2017
Investment Commitment		$ 12,674	$ 12,674
Development property investments, Fair Value		156	1,023
Development Property Investments [Member] | Minneapolis 1 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		285	1,150
Development Property Investments [Member] | Minneapolis 1 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 12,389	$ 11,524
Development Property Investments [Member] | Boston 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/1/2017	12/1/2017
Investment Commitment		$ 8,771	$ 8,771
Development property investments, Fair Value		2,235	1,220
Development Property Investments [Member] | Boston 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,329	1,306
Development Property Investments [Member] | Boston 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,442	$ 7,465
Development Property Investments [Member] | Miami [Member] | Construction Loans [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/23/2015	12/23/2015
Investment Commitment		$ 17,733	$ 17,733							$ 17,700
Development property investments, Fair Value		15,855	12,373
Development Property Investments [Member] | Miami [Member] | Construction Loans [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		15,966	12,492
Development Property Investments [Member] | Miami [Member] | Construction Loans [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 1,767	$ 5,241
Development Property Investments [Member] | New York City 4 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/15/2017	12/15/2017
Investment Commitment		$ 10,591	$ 10,591
Development property investments, Fair Value		1,168	823
Development Property Investments [Member] | New York City 4 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		1,283	927
Development Property Investments [Member] | New York City 4 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 9,308	$ 9,664
Development Property Investments [Member] | Boston 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/27/2017	12/27/2017
Investment Commitment		$ 10,174	$ 10,174
Development property investments, Fair Value		2,306	2,169
Development Property Investments [Member] | Boston 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,475	2,259
Development Property Investments [Member] | Boston 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 7,699	$ 7,915
Development Property Investments [Member] | New York City 5 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/28/2017	12/28/2017
Investment Commitment		$ 16,073	$ 16,073
Development property investments, Fair Value		4,945	4,178
Development Property Investments [Member] | New York City 5 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,101	4,303
Development Property Investments [Member] | New York City 5 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 10,972	11,770
Development Property Investments [Member] | Minneapolis 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		2/8/2018
Investment Commitment		$ 10,543
Development property investments, Fair Value		3,878
Development Property Investments [Member] | Minneapolis 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		3,944
Development Property Investments [Member] | Minneapolis 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 6,599
Development Property Investments [Member] | Philadelphia [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/30/2018
Investment Commitment		$ 14,338
Development property investments, Fair Value		3,274
Development Property Investments [Member] | Philadelphia [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		3,558
Development Property Investments [Member] | Philadelphia [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 10,780
Development Property Investments [Member] | Minneapolis 3 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		4/6/2018
Investment Commitment		$ 12,883
Development property investments, Fair Value		2,489
Development Property Investments [Member] | Minneapolis 3 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,613
Development Property Investments [Member] | Minneapolis 3 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 10,270
Development Property Investments [Member] | Miami 9 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/1/2018
Investment Commitment		$ 12,421
Development property investments, Fair Value		2,219
Development Property Investments [Member] | Miami 9 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,448
Development Property Investments [Member] | Miami 9 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 9,973
Development Property Investments [Member] | Atlanta 7 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/15/2018
Investment Commitment		$ 9,418
Development property investments, Fair Value		772
Development Property Investments [Member] | Atlanta 7 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		857
Development Property Investments [Member] | Atlanta 7 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 8,561
Development Property Investments [Member] | Kansas City [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		5/23/2018
Investment Commitment		$ 9,968
Development property investments, Fair Value		1,324
Development Property Investments [Member] | Kansas City [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		1,413
Development Property Investments [Member] | Kansas City [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 8,555
Development Property Investments [Member] | Orlando 5 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/7/2018
Investment Commitment		$ 12,969
Development Property Investments [Member] | Orlando 5 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 12,969
Development Property Investments [Member] | Los Angeles 2 [Member] | Loan investments [Member]
Schedule of Investments [Line Items]
Investment Closing Date		6/12/2018
Investment Commitment		$ 9,298
Development property investments, Fair Value		4,500
Development Property Investments [Member] | Los Angeles 2 [Member] | Loan investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		4,424
Development Property Investments [Member] | Los Angeles 2 [Member] | Loan investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		4,874
Bridge Loan Investments [Member]
Schedule of Investments [Line Items]
Investment Commitment		83,324
Bridge loan investments, Fair Value		79,581
Bridge Loan Investments [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		78,873
Bridge Loan Investments [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 4,451
Bridge Loan Investments [Member] | Miami 4 [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/2/2018
Investment Commitment		$ 20,201
Bridge loan investments, Fair Value		20,997
Bridge Loan Investments [Member] | Miami 4 [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		19,627
Bridge Loan Investments [Member] | Miami 4 [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 574
Bridge Loan Investments [Member] | Miami 5 [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/2/2018
Investment Commitment		$ 17,738
Bridge loan investments, Fair Value		14,009
Bridge Loan Investments [Member] | Miami 5 [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		16,108
Bridge Loan Investments [Member] | Miami 5 [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 1,630
Bridge Loan Investments [Member] | Miami 6 [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/2/2018
Investment Commitment		$ 13,370
Bridge loan investments, Fair Value		17,129
Bridge Loan Investments [Member] | Miami 6 [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		$ 13,370
Bridge Loan Investments [Member] | Miami 7 [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/2/2018
Investment Commitment		$ 18,462
Bridge loan investments, Fair Value		14,892
Bridge Loan Investments [Member] | Miami 7 [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		16,755
Bridge Loan Investments [Member] | Miami 7 [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 1,707
Bridge Loan Investments [Member] | Miami 8 [Member]
Schedule of Investments [Line Items]
Investment Closing Date		3/2/2018
Investment Commitment		$ 13,553
Bridge loan investments, Fair Value		12,554
Bridge Loan Investments [Member] | Miami 8 [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		13,013
Bridge Loan Investments [Member] | Miami 8 [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		540
Operating Property Loans [Member]
Schedule of Investments [Line Items]
Investment Commitment		5,982	5,982
Operating property loans, Fair Value		5,862	5,938
Operating Property Loans [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		5,980	5,980
Operating Property Loans [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 2	$ 2
Operating Property Loans [Member] | Newark [Member]
Schedule of Investments [Line Items]
Investment Closing Date		7/7/2015	7/7/2015
Investment Commitment		$ 3,480	$ 3,480
Operating property loans, Fair Value		3,402	3,447
Operating Property Loans [Member] | Newark [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		$ 3,480	$ 3,480
Operating Property Loans [Member] | Chicago [Member]
Schedule of Investments [Line Items]
Investment Closing Date		12/22/2015	12/22/2015
Investment Commitment		$ 2,502	$ 2,502
Operating property loans, Fair Value		2,460	2,491
Operating Property Loans [Member] | Chicago [Member] | Funded Investment [Member]
Schedule of Investments [Line Items]
Funded Investment		2,500	2,500
Operating Property Loans [Member] | Chicago [Member] | Unfunded Commitment [Member]
Schedule of Investments [Line Items]
Investment Commitment		$ 2	$ 2