INCOME TAXES - DEFERRED TAXES AND LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Net operating loss and credit carryforwards	$ 42,820	$ 75,350
Reserves and accruals	11,305	13,841
Depreciation and amortization	2,393	358
Other	6,645	7,128
Gross deferred tax assets	63,163	96,677
Valuation allowance	(31,648)	(55,827)
Total deferred tax assets	31,515	40,850
Intangible assets	(6,952)	(18,437)
Total deferred tax liabilities	(6,952)	(18,437)
Net deferred tax assets	$ 24,563	$ 22,413