Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 21,274	$ 18,228
Less: Accumulated depreciation and amortization	(15,634)	(12,781)
Property and equipment, net	5,640	5,447
Depreciation [Abstract]
Depreciation	2,947	2,861	$ 2,513
Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,085	6,106
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,054	1,053
Software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	8,180	7,408
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 4,955	$ 3,661