Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_TradingSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

FAIR VALUE DISCLOSURES - Financial instruments measured at fair value on recurring basis (Details) - Fair value on a recurring basis - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Assets:
Equity securities	$ 56	$ 237
Investments measured at net asset value	23,491	28,476
Level 1
Assets:
Equity securities	56	237
Level 2
Assets:
Equity securities
Investments measured at net asset value
Level 3
Assets:
Equity securities