Balance Sheet Components - Components of Balance Sheet Accounts (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property and equipment:
Office equipment	$ 495	$ 391
Office software	536	537
Machinery	24	0
Furniture and fixtures	222	59
Leasehold improvements	730	345
Construction in progress	10	75
Property and equipment, at cost	2,017	1,407
Accumulated depreciation and amortization	(1,123)	(931)
Property and equipment, net	894	476
Other accrued expenses:
Sales returns	1,552	654
Employee-related expense	11,064	4,620
Warehousing, inventory-related and other	4,087	1,469
Other accrued expenses	16,703	6,743
Deferred revenue:
Deferred revenue	4,011	2,687
Other current liabilities:
Unclaimed checks	1,064	1,266
Other	446	247
Other current liabilities	1,510	1,513
Unshipped product
Deferred revenue:
Deferred revenue	1,783	1,150
Auto ship advances
Deferred revenue:
Deferred revenue	1,597	815
Enrollment package revenue
Deferred revenue:
Deferred revenue	331	222
Market development fees
Deferred revenue:
Deferred revenue	$ 300	$ 500