INCOME TAXES - Deferred taxes and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating loss and credit carryforwards	$ 28,936	$ 42,345
Share-based compensation	10,559	7,241
Lease liabilities	7,315
Reserves and accruals	2,768	6,620
Other	4,030	7,069
Gross deferred tax assets	53,608	63,275
Valuation allowance	(5,971)	(8,152)
Total deferred tax assets	47,637	55,123
Right of use assets	(6,630)
Intangible assets	(4,021)	(4,463)
Others	(480)	0
Total deferred tax liabilities	(11,131)	(4,463)
Net deferred tax assets	$ 36,506	$ 50,660