Goodwill and Intangible Assets - Intangible Assets Other than Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 24,253	$ 15,798
Accumulated Amortization	(7,202)	(2,525)
Total	17,051	13,273
Not amortized, Gross Carrying Amount	1,772	1,945
Intangible assets, Gross Carrying Amount	26,025	17,743
Intangible Assets, Net Carrying Amount	18,823	15,218
Amortization of intangible assets	4,700	900	$ 800
TASER trademark
Acquired Indefinite-lived Intangible Assets [Line Items]
Not amortized, Gross Carrying Amount	900	900
Patents and trademarks pending
Acquired Indefinite-lived Intangible Assets [Line Items]
Not amortized, Gross Carrying Amount	872	1,045
Domain names
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	3,161	3,161
Accumulated Amortization	(428)	(125)
Total	$ 2,733	3,036
Domain names | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	5 years
Domain names | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	10 years
Issued patents
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 2,697	1,942
Accumulated Amortization	(913)	(780)
Total	$ 1,784	1,162
Issued patents | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Issued patents | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	15 years
Issued trademarks
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 860	655
Accumulated Amortization	(397)	(320)
Total	$ 463	335
Issued trademarks | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Issued trademarks | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	11 years
Customer relationships
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 1,377	914
Accumulated Amortization	(451)	(240)
Total	$ 926	674
Customer relationships | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Customer relationships | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	8 years
Non-compete agreements
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 556	465
Accumulated Amortization	(346)	(236)
Total	$ 210	229
Non-compete agreements | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Non-compete agreements | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	4 years
Developed technology
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortized, Gross Carrying Amount	$ 13,469	8,661
Accumulated Amortization	(3,956)	(824)
Total	$ 9,513	7,837
Developed technology | Minimum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	3 years
Developed technology | Maximum
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	7 years
Re-acquired distribution rights
Acquired Indefinite-lived Intangible Assets [Line Items]
Useful Life	2 years
Amortized, Gross Carrying Amount	$ 2,133	0
Accumulated Amortization	(711)	0
Total	$ 1,422	$ 0