Balance Sheet Account Details (Property and Equipment) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 4,229	$ 2,108
Accumulated depreciation	(1,084)	(376)
Total property and equipment, net	3,145	1,732
Computer Hardware
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	457	389
Software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	309	34
Lab equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,610	978
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	389	314
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 464	$ 393