Balance Sheet Components - Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement in Deferred Revenue [Roll Forward]
Beginning balances	$ 36,836	$ 42,432	$ 49,904
Deferral of revenue	45,040	40,003	46,193
Recognition of deferred revenue	(41,034)	(45,599)	(53,665)
Ending balances	$ 40,842	$ 36,836	$ 42,432