INCOME TAXES (Schedule of Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Reserves and others	$ 14,223	$ 10,869
Stock-based compensation	19,689	19,556
Net operating loss carryforward	5,956	8,115
Tax credit carryforward	23,073	14,183
Gross deferred tax assets	62,941	52,723
Valuation allowance	(18,381)	(28,566)
Total deferred tax assets	44,560	24,157
Deferred tax liabilities:
Depreciation and amortization	(16,666)	(12,813)
Disposal of a business unit	(7,454)	(7,152)
Deferred contract costs	(3,201)	(2,329)
Total deferred tax liabilities	(27,321)	(22,294)
Net deferred tax assets (liabilities)	$ 17,239	$ 1,863