FAIR VALUE MEASUREMENTS - Summary of Amortized Costs vs Fair Value (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Cost	$ 2,309,000	$ 2,271,000
Unrealized Gain	205,000	149,000
Unrealized Loss	(162,000)	(111,000)
Converted to Cash	(2,352,000)
Fair Value	0	2,309,000
Japanese Corporate Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	2,221,000	2,184,000
Unrealized Gain	198,000	144,000
Unrealized Loss	(156,000)	(107,000)
Converted to Cash	(2,263,000)
Fair Value	0	2,221,000
Japanese Government Bonds
Debt Securities, Available-for-sale [Line Items]
Cost	88,000	87,000
Unrealized Gain	7,000	5,000
Unrealized Loss	(6,000)	(4,000)
Converted to Cash	(89,000)
Fair Value	$ 0	$ 88,000