INCOME TAXES (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred income tax assets
Net operating loss carryforwards	$ 32,565	$ 51,042
Capital loss carryforwards	2,997	4,417
Intangible assets - finite life	3,137	3,261
Stock-based compensation	286	439
Property, plant & equipment		3,649
Deferred rent		799
Credits	1,148	1,281
Deferred revenue	1,939	2,755
Available-for-sale securities	9,984	8,644
Deferred compensation		1,053
Operating lease liability	13,215
Other	4,791	3,585
Deferred income tax assets	70,062	80,925
Deferred income tax liability - long-term
Intangible assets - indefinite-lived	(57,343)	(130,818)
Right-of-use asset - operating leases	(11,625)
Property and equipment	(193)
Deferred income tax liability - long-term	(69,161)	(130,818)
Less: Valuation allowance	(15,252)	(17,109)
Net deferred income tax liability - long-term	$ (14,351)	$ (67,002)