INCOME TAXES (Reconciliation of the Effective Tax Rate) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income tax at federal statutory rate	35.00%	35.00%	35.00%
State tax, net of federal tax effect	3.57%	21.29%	4.59%
Foreign income tax rate differential	0.50%	(1.54%)	(10.03%)
Stock-based compensation	(4.83%)	10.50%	(3.60%)
Income tax credits	(5.39%)	163.87%	14.30%
Change in valuation allowance	(30.24%)	(189.19%)	(96.18%)
Goodwill associated with Disposition	17.43%	0.00%	0.00%
Meals and entertainment	0.24%	(13.84%)	(2.63%)
Other non-deductible expenses	0.12%	(6.16%)	(1.58%)
Benefit for tax only asset	0.00%	0.00%	4.99%
Prior year deferred tax true-up	(0.12%)	(11.81%)	(0.57%)
Expiration of deferred tax benefit	0.00%	(50.76%)	0.00%
Other	0.80%	0.47%	(1.38%)
Effective tax rate	17.08%	(42.17%)	(57.09%)