FAIR VALUE DISCLOSURES - Financial instruments measured at fair value on recurring basis (Details) - Fair value on a recurring basis - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets:
Equity securities	$ 78	$ 237
Investments measured at net asset value	28,657	28,476
Level 1
Assets:
Equity securities	$ 78	$ 237