TREASURY UNITS (Details)				1 Months Ended	2 Months Ended	3 Months Ended		6 Months Ended		132 Months Ended	142 Months Ended
	Mar. 10, 2015 shares	Aug. 31, 2007 $ / item shares	Aug. 20, 2007 shares	Sep. 30, 2007 $ / item shares	Aug. 31, 2020 shares	Mar. 31, 2019 $ / item shares	Dec. 31, 2007 $ / item shares	Jun. 30, 2020 USD ($) $ / item shares	Jun. 30, 2019 USD ($) $ / item shares	Dec. 31, 2018 $ / item shares	Jun. 30, 2019 USD ($) $ / item	Mar. 06, 2008 shares
Treasury units								58,469
Period for repurchase of depository receipts	5 years		12 months
Depository receipts authorized to be repurchased	2,000,000		300,000									1,500,000
Number of depository receipts repurchased		1,428,437		1,428,437			1,428,437		1,428,437	1,428,437
Repurchase price of depository receipts (in dollars per receipt) | $ / item											28.43
Units required to be repurchased (in shares)								222	1,995
Total cost of repurchase | $								$ 394,031	$ 3,305,651		$ 44,718,000
Subsequent event
Number of depository receipts repurchased					0
General Partnership
Treasury units								585
Fixed distribution percentage of unit holders								1.00%
Number of depository receipts repurchased		188		188		188				188
Total cost of repurchase | $								$ 3,941	$ 33,055
Value of units required to be repurchased | $								$ 3,939
Repurchases required (in units)								2.22
Treasury Units
Units required to be repurchased (in shares)								222	1,995
Class A
Treasury units								46,775
Fixed distribution percentage of unit holders								80.00%
Repurchase price of units (in dollars per unit) | $ / item		852.90		852.90		852.90				852.90
Total cost of repurchase | $								$ 315,220	$ 2,644,552
Class B
Treasury units								11,109
Fixed distribution percentage of unit holders								19.00%
Number of depository receipts repurchased		3,572		3,572		3,572				3,572
Total cost of repurchase | $								$ 74,870	$ 628,044
Class B
Value of units required to be repurchased | $								$ 74,839
Class B | General Partnership
Repurchase price of units (in dollars per unit) | $ / item		1,033.00		1,033.00			1,033.00		1,033.00	1,033.00
Repurchases required (in units)								42.18
Treasury Units
Repurchase price of depository receipts (in dollars per receipt) | $ / item								59.14
Units required to be repurchased (in shares)								5,328
Repurchase price of units (in dollars per unit) | $ / item								1,774.20
Total cost of repurchase | $								$ 315,216