QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenue	$ 9,104,015	$ 8,875,596	$ 8,800,416	$ 8,852,382	$ 8,760,538	$ 8,648,526	$ 8,345,643	$ 8,280,894	$ 35,632,409	$ 34,035,602	$ 32,255,957
Expenses	5,704,596	5,730,319	5,413,735	5,861,694	5,722,971	5,665,232	5,508,842	5,773,941	22,710,344	22,670,986	21,916,664
Income Before Other Income (loss) and Discontinued Operations	3,399,419	3,145,277	3,386,681	2,990,688	3,037,567	2,983,294	2,836,801	2,506,953	12,922,065	11,364,616	10,339,293
Income (loss) from discontinued operations					(308)	(3,054)	7,736,789	68,599		7,802,026	219,867
Other Income (loss)	(2,214,288)	(2,370,824)	(2,339,420)	(2,363,735)	(2,469,002)	(2,523,314)	(2,480,305)	(2,402,740)	(9,288,267)	(9,875,361)	(11,918,392)
Net Income (loss)	$ 1,185,131	$ 774,453	$ 1,047,261	$ 626,953	$ 568,257	$ 456,926	$ 8,093,285	$ 172,812	$ 3,633,798	$ 9,291,281	$ (1,359,232)
Net Income (loss) per Unit before discontinued operations (in dollars per unit)	$ 9.07	$ 5.90	$ 7.97	$ 4.77	$ 4.33	$ 3.50	$ 2.71	$ 0.79	$ 27.69	$ 11.33	$ (11.99)
Income (loss) per Unit from discontinued operations (in dollars per unit)						$ (0.02)	$ 58.84	$ 0.52		$ 59.34	$ 1.67
Net Income per Unit (in dollars per unit)	$ 9.07	$ 5.90	$ 7.97	$ 4.77	$ 4.33	$ 3.48	$ 61.55	$ 1.31	$ 27.69	$ 70.67	$ (10.32)
Income per depositary receipt before discontinued operations (in dollars per share)	$ 0.30	$ 0.20	$ 0.27	$ 0.16	$ 0.15	$ 0.12	$ 0.09	$ 0.02	$ 0.92	$ 0.38
Income per depositary receipt from discontinued operations (in dollars per share)	$ 0.00	$ 0.00	$ 0.00	$ 0.00			$ 1.96	$ 0.02	$ 0.00	$ 1.98
Net Income (loss) per Depositary Receipt after Discontinued Operations (in dollars per share)					$ 0.15	$ 0.12	$ 2.05	$ 0.04	$ 0.92	$ 2.36
Net Income per depositary receipt	$ 0.30	$ 0.20	$ 0.27	$ 0.16					$ 0.92