QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares $ / item	Sep. 30, 2020 USD ($) $ / shares $ / item	Jun. 30, 2020 USD ($) $ / shares $ / item	Mar. 31, 2020 USD ($) $ / shares $ / item	Dec. 31, 2019 USD ($) $ / shares $ / item	Sep. 30, 2019 USD ($) $ / shares $ / item	Jun. 30, 2019 USD ($) $ / shares $ / item	Mar. 31, 2019 USD ($) $ / shares $ / item	Dec. 31, 2020 USD ($) $ / shares $ / item	Dec. 31, 2019 USD ($) $ / shares $ / item	Dec. 31, 2018 USD ($) $ / shares
QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenue	$ 14,825,754	$ 15,142,266	$ 15,759,106	$ 16,375,584	$ 15,447,866	$ 15,155,901	$ 14,991,403	$ 14,882,144	$ 62,102,710	$ 60,477,314	$ 58,014,064
Expenses	11,873,260	11,914,630	11,314,637	12,031,150	10,883,950	10,978,884	10,412,256	10,930,457	47,133,677	43,205,547
Income Before Other Income (Expense)	2,952,494	3,227,636	4,444,469	4,344,434	4,563,916	4,177,017	4,579,147	3,951,687	14,969,033	17,271,767	14,918,372
Other Expenses	(3,922,516)	(3,666,920)	(2,979,418)	(2,975,651)	(2,665,403)	(2,793,038)	(2,814,903)	(2,451,171)	(13,544,505)	(10,724,515)	(10,749,282)
Net (Loss) Income	$ (970,022)	$ (439,284)	$ 1,465,051	$ 1,368,783	$ 1,898,513	$ 1,383,979	$ 1,764,244	$ 1,500,516	$ 1,424,528	$ 6,547,252	$ 4,169,090
Net Income per Unit before Discontinued Operations | $ / shares	$ (7.95)	$ (3.61)	$ 12.03	$ 11.23	$ 15.55	$ 11.32	$ 14.40	$ 12.21	$ 11.70	$ 53.48
Net (Loss) Income per Unit (in dollars per unit) | $ / shares	$ (7.95)	$ (3.61)	$ 12.03	$ 11.23	$ 15.55	$ 11.32	$ 14.40	$ 12.21	$ 11.70	$ 53.48	$ 33.52
Income Per Depositary Receipt Before Discontinued Operations (in dollars per unit) | $ / item	(0.27)	(0.12)	0.40	0.37	0.51	0.38	0.48	0.41	0.39	1.78
Net Income Per Depositary Receipt (in dollars per receipt) | $ / item	(0.27)	(0.12)	0.40	0.37	0.51	0.38	0.48	0.41	0.39	1.78