INVESTMENTS, AVAILABLE-FOR-SALE SECURITIES (Details) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Available-for-sale Securities Reconciliation [Abstract]
Amortized cost	$ 10,800,000	$ 15,942,000
Gross unrealized gains	0	610,000
Gross unrealized losses	(848,000)	(1,045,000)
Fair Value	9,952,000	15,507,000
Available-for-sale securities, unrealized loss positions
Continuous unrealized loss position, 12 months or more, aggregated fair value	9,952,000	14,455,000
Continuous unrealized loss position, 12 months or more, gross unrealized losses	(848,000)	(1,045,000)
Continuous unrealized loss position, less than 12 months	0	0
Auction Rate Securities [Member]
Available-for-sale Securities Reconciliation [Abstract]
Amortized cost	10,800,000	15,942,000
Gross unrealized gains	0	610,000
Gross unrealized losses	(848,000)	(1,045,000)
Fair Value	9,952,000	15,507,000
Available-for-sale securities, unrealized loss positions
Continuous unrealized loss position, 12 months or more, aggregated fair value	9,952,000	14,455,000
Continuous unrealized loss position, 12 months or more, gross unrealized losses	$ (848,000)	$ (1,045,000)