Goodwill and Intangible Assets

The changes in the carrying amount of goodwill for the nine months ended September 30, 2018 were as follows (in thousands):



	TASER Weapons			Software and Sensors			Total
Balance, beginning of period	$	1,453		$	13,474		$	14,927
Goodwill acquired	—			10,285			10,285
Foreign currency translation adjustment	(84		)	(85		)	(169		)
Balance, end of period	$	1,369		$	23,674		$	25,043

Intangible assets (other than goodwill) consisted of the following (in thousands):



		September 30, 2018							December 31, 2017
	Useful Life	Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization			Net Carrying Amount
Amortized:
Domain names	5-10 years	$	3,161	$	(656	)	$	2,505	$	3,161	$	(428	)	$	2,733
Issued patents	4-15 years	2,916		(1,054		)	1,862		2,697		(913		)	1,784
Issued trademarks	3-11 years	1,052		(567		)	485		860		(397		)	463
Customer relationships	4-8 years	3,724		(755		)	2,969		1,377		(451		)	926
Non-compete agreements	3-4 years	545		(423		)	122		556		(346		)	210
Developed technology	3-7 years	15,449		(8,573		)	6,876		13,469		(3,956		)	9,513
Re-acquired distribution rights	2 years	1,973		(1,644		)	329		2,133		(711		)	1,422
Total amortized		28,820		(13,672		)	15,148		24,253		(7,202		)	17,051
Not amortized:
TASER trademark		900					900		900					900
Patents and trademarks pending		908					908		872					872
Total not amortized		1,808					1,808		1,772					1,772
Total intangible assets		$	30,628	$	(13,672	)	$	16,956	$	26,025	$	(7,202	)	$	18,823

During the three months ended September 30, 2018, we abandoned certain developed technology acquired in a business combination resulting in an impairment charge of approximately $2.0 million.

Amortization expense of intangible assets for the three and nine months ended September 30, 2018 was $1.6 million and $4.6 million, respectively. Amortization expense of intangible assets for the three and nine months ended September 30, 2017 was $1.4 million and $3.3 million, respectively. Estimated amortization for intangible assets with definite lives for the remaining three months of 2018, the next five years ended December 31, and thereafter, is as follows (in thousands):



2018	$	1,209
2019	3,357
2020	3,296
2021	2,854
2022	1,200
2023	1,393
Thereafter	1,839
Total	$	15,148