Securities Available For Sale - Summary of Available-for-sale Securities (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Cost		$ 121,444,694	$ 92,038,001
Market Value		$ 132,964,276	$ 108,755,172
CBL & Associates Properties, Inc Preferred Stock Series D [Member]
Interest Rate		7.375%	7.375%
Number of Shares		2,000	2,000
Cost		$ 50,269	$ 50,269
Market Value		$ 43,720	$ 48,900
CBL & Associates Properties, Inc Preferred Stock Series E [Member]
Interest Rate		6.625%	6.625%
Number of Shares		62,724	62,724
Cost		$ 1,487,145	$ 1,487,145
Market Value		$ 1,383,064	$ 1,440,789
Cedar Realty Trust, Inc Preferred Stock Series B [Member]
Interest Rate		7.25%	7.25%
Number of Shares		18,269	58,577
Cost		$ 422,544	$ 1,411,846
Market Value		$ 458,755	$ 1,426,126
Cedar Realty Trust, Inc Preferred Stock Series C [Member]
Interest Rate		6.50%
Number of Shares		20,000
Cost		$ 494,407
Market Value		$ 500,800
Colony Northstar, Inc. Preferred Stock Series I [Member]
Interest Rate		7.15%
Number of Shares		20,000
Cost		$ 500,000
Market Value		$ 503,600
Investors Real Estate Trust Preferred Stock Series C [Member]
Interest Rate		6.625%
Number of Shares		20,000
Cost		$ 500,000
Market Value		$ 520,308
Pennsylvania Real Estate Investment Trust Preferred Stock Series B [Member]
Interest Rate		7.375%	7.375%
Number of Shares		40,000	40,000
Cost		$ 1,000,000	$ 1,000,000
Market Value		$ 1,007,200	$ 1,000,000
Pennsylvania Real Estate Investment Trust Preferred Stock Series D [Member]
Interest Rate		6.875%
Number of Shares		20,000
Cost		$ 498,207
Market Value		$ 502,200
Urstadt Biddle Properties, Inc Preferred Stock Series G [Member]
Interest Rate		6.75%	6.75%
Number of Shares		5,000	5,000
Cost		$ 125,000	$ 125,000
Market Value		$ 131,000	128,000
Urstadt Biddle Properties, Inc Preferred Stock Series H [Member]
Interest Rate		6.25%
Number of Shares		12,500
Cost		$ 312,500
Market Value		326,875
Preferred Stock [Member]
Cost		5,390,072	12,857,467
Market Value		$ 5,377,522	$ 13,028,200
CBL & Associates Properties, Inc [Member]
Number of Shares		1,500,000	1,000,000
Cost		$ 16,157,749	$ 11,785,016
Market Value		$ 8,490,000	$ 11,500,000
Franklin Street Properties Corporation [Member]
Number of Shares		150,000
Cost		$ 1,659,118
Market Value		$ 1,611,000
Government Properties Income Trust [Member]
Number of Shares		1,020,000	810,000
Cost		$ 19,430,983	$ 15,520,076
Market Value		$ 18,910,800	$ 15,442,650
Kimco Realty Corporation [Member]
Number of Shares		750,000
Cost		$ 14,475,908
Market Value		$ 13,612,500
Monmouth Real Estate Investment Corporation [Member]
Number of Shares	[1]	2,335,930	2,237,588
Cost	[1]	$ 20,698,562	$ 19,231,411
Market Value	[1]	$ 41,579,558	$ 34,100,835
Pennsylvania Real Estate Investment Trust [Member]
Number of Shares		150,000
Cost		$ 1,602,636
Market Value		$ 1,783,500
Select Income Real Estate Investment Trust [Member]
Number of Shares		775,000	740,000
Cost		$ 18,649,691	$ 17,802,516
Market Value		$ 19,475,750	$ 18,648,000
Senior Housing Properties Trust [Member]
Number of Shares		160,911	220,911
Cost		$ 2,739,069	$ 3,760,406
Market Value		$ 3,081,446	$ 4,181,845
Tanger Factory Outlet [Member]
Number of Shares		120,000
Cost		$ 2,941,621
Market Value		$ 3,181,200
Urstadt Biddle Properties, Inc [Member]
Number of Shares		100,000	85,000
Cost		$ 2,048,516	$ 1,761,151
Market Value		$ 2,174,000	$ 2,049,350
Vereit, Inc [Member]
Number of Shares		1,300,000	500,000
Cost		$ 11,253,514	$ 4,512,658
Market Value		$ 10,127,000	4,230,000
Washington Prime Group [Member]
Number of Shares		500,000
Cost		$ 4,397,255
Market Value		3,560,000
Common Stock [Member]
Cost		116,054,622	79,180,534
Market Value		$ 127,586,754	$ 95,726,972
Ashford Hospitality Trust, Inc Preferred Stock Series A [Member]
Interest Rate			8.55%
Number of Shares			10,000
Cost			$ 251,205
Market Value			$ 253,800
Chesapeake Lodging Trust Preferred Stock Series A [Member]
Interest Rate			7.75%
Number of Shares			20,000
Cost			$ 500,000
Market Value			$ 507,806
Corporate Office Properties Trust Preferred Stock Series L [Member]
Interest Rate			7.375%
Number of Shares			26,000
Cost			$ 650,330
Market Value			$ 656,760
Kilroy Realty Corporation Preferred Stock Series G [Member]
Interest Rate			6.875%
Number of Shares			34,948
Cost			$ 844,770
Market Value			$ 885,932
LaSalle Hotel Properties Preferred Stock Series H [Member]
Interest Rate			7.50%
Number of Shares			40,000
Cost			$ 982,589
Market Value			$ 1,002,000
Pennsylvania Real Estate Investment Trust Preferred Stock Series A [Member]
Interest Rate			8.25%
Number of Shares			68,800
Cost			$ 1,720,885
Market Value			$ 1,739,952
Retail Properties of America, Inc Preferred Stock Series A [Member]
Interest Rate			7.00%
Number of Shares			20,000
Cost			$ 481,949
Market Value			$ 500,000
Stag Industrial, Inc Preferred Stock Series B [Member]
Interest Rate			6.625%
Number of Shares			20,100
Cost			$ 470,007
Market Value			$ 501,495
Summit Hotel Properties, Inc Preferred Stock Series B [Member]
Interest Rate			7.875%
Number of Shares			20,000
Cost			$ 500,000
Market Value			$ 514,780
Sun Communities, Inc Preferred Stock Series A [Member]
Interest Rate			7.125%
Number of Shares			45,000
Cost			$ 1,117,377
Market Value			$ 1,133,550
Terreno Realty Corporation Preferred Stock Series A [Member]
Interest Rate			7.75%
Number of Shares			20,300
Cost			$ 507,791
Market Value			$ 512,575
Urstadt Biddle Properties, Inc Preferred Stock Series F [Member]
Interest Rate			7.125%
Number of Shares			30,421
Cost			$ 756,304
Market Value			$ 775,735
Cousins Properties, Inc. [Member]
Number of Shares			105,950
Cost			$ 820,348
Market Value			$ 901,635
Gladstone Commercial Corporation [Member]
Number of Shares			180,000
Cost			$ 3,199,933
Market Value			$ 3,618,000
Nobility Homes Inc [Member]
Number of Shares			20,000
Cost			$ 158,200
Market Value			$ 315,000
Parkway Properties Inc [Member]
Number of Shares			33,243
Cost			$ 628,819
Market Value			$ 739,657

[1] Related entity - See Note 8.