Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets, Net [Abstract]
Intangible assets amortization expense	$ 300,000	$ 200,000
Impairment of goodwill	$ 0
Birdstep Technology AB [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Impairment loss of intangible assets		$ 400,000