TREASURY UNITS (Details)				1 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	Aug. 05, 2019 USD ($) $ / item shares	Sep. 30, 2007 $ / item shares	Mar. 31, 2019 $ / item shares	Dec. 31, 2007 $ / item shares	Jun. 30, 2019 USD ($) $ / item shares	Dec. 31, 2018 $ / item shares	Jun. 30, 2019 USD ($) $ / item shares	Mar. 06, 2008 shares
Treasury units								57,834		57,834
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		1,413,200			1,413,200		1,413,200	1,413,200	1,413,200
Repurchase price of depository receipts (in dollars per receipt) | $ / item										28.09
Units required to be repurchased (in shares)								1,995
Total cost of repurchase | $								$ 3,305,651		$ 43,579,000
Subsequent event
Number of depository receipts repurchased				1,660
Repurchase price of depository receipts (in dollars per receipt) | $ / item				60.20
Total cost of repurchase | $				$ 99,972
General Partnership
Treasury units								579		579
Fixed distribution percentage of unit holders								1.00%
Number of depository receipts repurchased		182			182	182			182
Units required to be repurchased (in shares)								20
Total cost of repurchase | $								$ 33,055
Value of units required to be repurchased | $								$ 33,055
General Partnership | Subsequent event
Units required to be repurchased (in shares)				1
Value of units required to be repurchased | $				$ 1,249
Treasury Units
Units required to be repurchased (in shares)								1,995
Class A
Treasury units								46,267		46,267
Fixed distribution percentage of unit holders								80.00%
Repurchase price of units (in dollars per unit) | $ / item		842.64			842.64	842.64			842.64
Total cost of repurchase | $								$ 2,644,552
Class B
Treasury units								10,988		10,988
Fixed distribution percentage of unit holders								19.00%
Number of depository receipts repurchased		345			345	345			345
Total cost of repurchase | $								$ 628,044
Class B | Subsequent event
Units required to be repurchased (in shares)				13
Value of units required to be repurchased | $				$ 23,735
Class B
Value of units required to be repurchased | $								$ 628,044
Class B | General Partnership
Units required to be repurchased (in shares)								379
Repurchase price of units (in dollars per unit) | $ / item		1,006.45			1,006.45		1,006.45	1,006.45	1,006.45
Treasury Units
Repurchase price of depository receipts (in dollars per receipt) | $ / item								55.21
Units required to be repurchased (in shares)								47,894
Repurchase price of units (in dollars per unit) | $ / item								1,656.40
Total cost of repurchase | $								$ 2,644,546