SUBSEQUENT EVENTS (Details)		1 Months Ended		3 Months Ended			6 Months Ended	132 Months Ended	142 Months Ended
	Aug. 31, 2007 shares	May 08, 2020 USD ($) $ / item shares	Sep. 30, 2007 shares	Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($) shares	Dec. 31, 2007 shares	Jun. 30, 2019 shares	Dec. 31, 2018 shares	Jun. 30, 2019 USD ($) $ / item
Subsequent events
Number of depository receipts repurchased | shares	14,283		14,283			14,283	14,283	14,283
Repurchase price of depository receipts (in dollars per receipt) | $ / item									28.42
Total cost of repurchase				$ 389,947	$ 2,930,736				$ 44,714,000
Units required to be repurchased (in shares) | shares				219	1,795
Subsequent event
Subsequent events
Number of depository receipts repurchased | shares		76
Repurchase price of depository receipts (in dollars per receipt) | $ / item		42.95
Price per unit of depository receipts | $ / item		1,288.50
Total cost of repurchase		$ 3,265
Class B
Subsequent events
Number of depository receipts repurchased | shares	3,571		3,571		3,571			3,571
Total cost of repurchase				$ 3,900	$ 556,828
Class B | Subsequent event
Subsequent events
Units required to be repurchased (in shares) | shares		0.6
Value of units required to be repurchased		$ 775
General Partnership
Subsequent events
Number of depository receipts repurchased | shares	188		188		188			188
Total cost of repurchase				311,952	$ 29,307
Value of units required to be repurchased				$ 3,898
General Partnership | Subsequent event
Subsequent events
Value of units required to be repurchased		$ 41