Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued Liabilities Current [Abstract]
Accrued royalty expense	$ 7,939	$ 17,165
Accrued inventory	6,008	2,382
Accrued payroll and related expenses	12,217	8,699
Accrued cost of revenue	22,830	12,210
Accrued payments to content publishers	32,463	24,037
Taxes and related liabilities	1,314	1,463
Customer prepayments	3,124	545
Other accrued expenses	6,091	5,843
Total Accrued Liabilities	$ 91,986	$ 72,344