Balance Sheet Components - Intangible Asset Amortization Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 2,585	$ 592	$ 2,585	$ 592	$ 12
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	920	266			0
Developed technology
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	1,569	318			11
Trade name
Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 96	$ 8			$ 1