FAIR VALUE MEASUREMENTS - Recurring basis (Details) - USD ($)	Jun. 30, 2019	Jun. 30, 2018
Assets:
Investment in marketable securities	$ 9,696,000	$ 13,841,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Assets:
Investment in marketable securities	9,696,000	13,841,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | REITs and real estate companies [Member]
Assets:
Investment in marketable securities	3,069,000	4,300,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Consumer Cyclical [Member]
Assets:
Investment in marketable securities	1,448,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member]
Assets:
Investment in marketable securities	1,420,000	2,282,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Technology [Member]
Assets:
Investment in marketable securities		1,813,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Healthcare [Member]
Assets:
Investment in marketable securities		1,777,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Communications [Member]
Assets:
Investment in marketable securities		1,071,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Financial Services [Member]
Assets:
Investment in marketable securities	951,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Energy [Member]
Assets:
Investment in marketable securities	950,000
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Assets:
Investment in marketable securities	$ 1,858,000	$ 2,598,000