BALANCE SHEET DETAILS - Other Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Other Assets, Net [Abstract]
Contract assets - long-term	$ 2,451	$ 4,596
Right-of-use ("ROU") assets	1,075	1,607
Deferred tax assets	2,659	2,659
Marketable debt securities - non-current	7,466	0
Other assets	185	138
Total other assets	$ 13,836	$ 9,000