Segment Data - Summary of Operational Information Relative to the Company's Reportable Segments (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Net sales from products									$ 285,859	$ 238,573	$ 185,230
Net sales from services									57,939	29,672	12,662
Net sales	$ 94,651	$ 90,262	$ 79,643	$ 79,242	$ 82,077	$ 71,882	$ 58,756	$ 55,530	343,798	268,245	197,892
Cost of product sales									117,997	91,536	65,022
Cost of service sales									18,713	6,173	4,223
Cost of sales									136,710	97,709	69,245
Gross margin	$ 63,016	$ 49,765	$ 45,637	$ 48,670	$ 49,770	$ 46,565	$ 37,299	$ 36,902	207,088	170,536	128,647
Sales, general and administrative									138,692	108,076	69,698
Research and development									55,373	30,609	23,614
Income from operations									13,023	31,851	35,335
Purchase of property and equipment									10,419	4,957	6,003
Purchase of intangible assets									1,024	3,495	501
Purchase of property and equipment and intangible assets, including goodwill, in connection with business acquisitions									12,699	6,825	12,599
Depreciation and amortization									8,041	3,658	3,291
TASER Weapons
Segment Reporting Information [Line Items]
Net sales from products									234,512	202,644	162,375
Net sales from services									0	0	0
Net sales									234,512	202,644	162,375
Cost of product sales									72,054	61,930	48,821
Cost of service sales									0	0	0
Cost of sales									72,054	61,930	48,821
Gross margin									162,458	140,714	113,554
Sales, general and administrative									78,202	63,617	47,640
Research and development									8,377	5,887	4,470
Income from operations									75,879	71,210	61,444
Purchase of property and equipment									4,341	4,129	4,159
Purchase of intangible assets									259	262	277
Purchase of property and equipment and intangible assets, including goodwill, in connection with business acquisitions									2,075	0	1,453
Depreciation and amortization									2,705	2,207	2,311
Software and Sensors
Segment Reporting Information [Line Items]
Net sales from products									51,347	35,929	22,855
Net sales from services									57,939	29,672	12,662
Net sales									109,286	65,601	35,517
Cost of product sales									45,943	29,606	16,201
Cost of service sales									18,713	6,173	4,223
Cost of sales									64,656	35,779	20,424
Gross margin									44,630	29,822	15,093
Sales, general and administrative									60,490	44,459	22,058
Research and development									46,996	24,722	19,144
Income from operations									(62,856)	(39,359)	(26,109)
Purchase of property and equipment									6,078	828	1,844
Purchase of intangible assets									765	3,233	224
Purchase of property and equipment and intangible assets, including goodwill, in connection with business acquisitions									10,624	6,825	11,146
Depreciation and amortization									$ 5,336	$ 1,451	$ 980