Balance Sheet Components - Operating Leases (Details) $ in Thousands	Jun. 30, 2020 USD ($)	Jan. 01, 2020 USD ($) floor	Dec. 31, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Operating lease asset	$ 21,645		$ 21,908
Building Floor
Property, Plant and Equipment [Line Items]
Number of additional floors | floor		1
Operating lease asset		$ 1,700
Operating lease liability		$ 1,700
Term of contract	5 years
Renewal term	5 years
Total minimum lease payments	$ 2,100