QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares $ / item	Sep. 30, 2015 USD ($) $ / shares $ / item	Jun. 30, 2015 USD ($) $ / shares $ / item	Mar. 31, 2015 USD ($) $ / shares $ / item	Dec. 31, 2014 USD ($) $ / shares $ / item	Sep. 30, 2014 USD ($) $ / shares $ / item	Jun. 30, 2014 USD ($) $ / shares $ / item	Mar. 31, 2014 USD ($) $ / shares $ / item	Dec. 31, 2015 USD ($) $ / shares $ / item	Dec. 31, 2014 USD ($) $ / shares $ / item	Dec. 31, 2013 USD ($) $ / shares
QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenue	$ 12,133,802	$ 11,209,974	$ 11,061,418	$ 11,075,520	$ 10,810,827	$ 10,643,029	$ 10,560,535	$ 10,617,928	$ 45,480,714	$ 42,632,319	$ 38,364,552
Expenses	8,653,490	7,874,926	7,810,234	8,430,376	7,924,264	7,916,421	7,835,735	8,053,306	32,769,026	31,729,726	27,233,135
Income Before Other Income (Expense) and Discontinued Operations	3,480,312	3,335,048	3,251,184	2,645,144	2,886,563	2,726,608	2,724,800	2,564,622	12,711,688	10,902,593	11,131,417
Income (Loss) From Discontinued Operations											3,697,886
Other Income (Loss)	(2,287,608)	(2,261,302)	(2,154,727)	(2,235,486)	(2,295,307)	(2,545,121)	(2,443,079)	(2,594,236)	(8,939,123)	(9,877,743)	(9,173,918)
Net Income	$ 1,192,704	$ 1,073,746	$ 1,096,457	$ 409,658	$ 591,256	$ 181,487	$ 281,721	$ (29,614)	$ 3,772,565	$ 1,024,850	$ 5,655,385
Net Income (Loss) per Unit before Discontinued Operations (in dollars per unit) | $ / shares	$ 9.47	$ 8.51	$ 8.66	$ 3.22	$ 4.60	$ 1.41	$ 2.18	$ (0.23)	$ 29.86	$ 7.96	$ 15.07
Net Income per Unit (in dollars per unit) | $ / shares	$ 9.47	$ 8.51	$ 8.66	$ 3.22	$ 4.60	$ 1.41	$ 2.18	$ (0.23)	$ 29.86	$ 7.96	$ 43.55
Income Per Depositary Receipt Before Discontinued Operations (in dollars per unit) | $ / item	0.32	0.28	0.29	0.11	0.15	0.05	0.07	(0.01)	1.00	0.27
Net Income (Loss) per Depositary Receipt after Discontinued Operations (in dollars per receipt) | $ / item	0.32	0.28	0.29	0.11	0.15	0.05	0.07	(0.01)	1.00	0.27