FAIR VALUE MEASUREMENTS - Unrealized Gain Position (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair value of marketable equity securities, carrying amount	$ 0	$ 10,582,000
Fair value of marketable securities, less then 12 months	0	10,582,000
Fair value of marketable securities, 12 months or greater	0	0
Fair value of marketable securities, total	0	10,582,000
Unrealized gains, carrying amount	0	0
Unrealized gains, less than 12 months	0	3,043,000
Unrealized gains, 12 months or greater	0	0
Unrealized gains, total	$ 0	$ 3,043,000