BALANCE SHEET COMPONENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash, cash equivalents and restricted cash:
Cash and cash equivalents	$ 118,699	$ 132,653
Restricted cash	3,068	2,998
Cash, cash equivalents and restricted cash	121,767	135,651	$ 148,374	$ 138,478
Inventories:
Finished goods	11,608	11,171
Raw materials	1,221	1,145
Reserve for obsolescence	(519)	(151)
Inventories, net	12,310	12,165
Other accrued expenses:
Sales returns	508	801
Employee-related expense	2,770	4,051
Warehousing, inventory-related and other	1,545	1,269
Other accrued expenses	4,823	6,121
Deferred revenue:
Deferred revenue	3,754	6,795
Unshipped product
Deferred revenue:
Deferred revenue	1,581	4,574
Auto ship advances
Deferred revenue:
Deferred revenue	1,928	1,876
Other
Deferred revenue:
Deferred revenue	245	345
Cash
Cash, cash equivalents and restricted cash:
Cash and cash equivalents	32,722	47,323
Cash equivalents
Cash, cash equivalents and restricted cash:
Cash and cash equivalents	$ 85,977	$ 85,330