Details of Certain Consolidated Balance Sheet Accounts - Schedule of Property and Equipment, Net(Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 20,349	$ 16,774
Accumulated depreciation and amortization	(8,753)	(7,815)
Property and equipment, net	11,596	8,959
Deployed Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	17,091	13,240
Computer Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,123	912
Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	312	202
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	165	151
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	202	185
Construction in Progress
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,456	$ 2,084