RENTAL PROPERTIES (Reconciliation) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Rental Properties
Balance, Beginning	$ 263,659,293	$ 261,276,898
Additions:
Buildings, improvements and other assets	50,784,476	5,163,081	$ 37,895,926
Balance before deductions	314,443,769	266,439,979	262,917,872
Deduct:
Write-offs of retired or disposed assets	2,492,172	2,112,142	1,640,974
Rental properties held for sale and/or sold		668,544
Balance, Ending	311,951,597	263,659,293	261,276,898
Accumulated Depreciation
Balance, Beginning	94,196,482	84,579,584
Add:
Depreciation for the year	13,093,493	11,729,039	10,314,696
Total additions	107,289,975	96,308,623	86,220,558
Deduct:
Accumulated depreciation of retired or disposed assets	2,492,172	2,112,141	1,640,974
Balance, Ending	$ 104,797,803	$ 94,196,482	$ 84,579,584