Commitments and Contingencies - Additional Information (Detail) $ in Thousands	1 Months Ended				3 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2017 USD ($) ft²	Jul. 31, 2017 USD ($)	Apr. 30, 2017 ft²	Jun. 30, 2016 USD ($) ft²	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Commitments And Contingencies Disclosure [Line Items]
Restructuring reserve					$ 108		$ 108		$ 196
Rent expense under leases					200	$ 200	700	$ 700
Operating lease obligation					3,343		3,343
Allowance for product returns							200		200
Warranty reserve					418		$ 418		394
Antenna [Member]
Commitments And Contingencies Disclosure [Line Items]
Repair and replacement warranty							5 years
Warranty Reserves [Member]
Commitments And Contingencies Disclosure [Line Items]
Warranty reserve					418	$ 319	$ 418	$ 319	394	$ 348
Beijing Design Center [Member]
Commitments And Contingencies Disclosure [Line Items]
Lease term				4 years
Area of office space | ft²				11,270
Operating lease obligation				$ 400
Tianjin Facility [Member]
Commitments And Contingencies Disclosure [Line Items]
Area of office space | ft²			22,120
Operating lease obligation					35		$ 35
Lease expiration date			Apr. 11, 2018
Akron, Ohio [Member]
Commitments And Contingencies Disclosure [Line Items]
Lease term	7 years
Area of office space | ft²	5,977
Operating lease obligation	$ 700
Lease commencement date	Jan. 01, 2018
Colorado Office [Member]
Commitments And Contingencies Disclosure [Line Items]
Lease expiration date							Oct. 31, 2020
Colorado Office [Member] | Landlord [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease obligation					400		$ 400
Melbourne, Florida [Member]
Commitments And Contingencies Disclosure [Line Items]
Operating lease obligation		$ 78,000
Lease expiration date		Dec. 31, 2018
Accrued Liabilities [Member]
Commitments And Contingencies Disclosure [Line Items]
Restructuring reserve					24		24		100
Long-term Liabilities [Member]
Commitments And Contingencies Disclosure [Line Items]
Restructuring reserve					$ 84		$ 84		$ 100