M. GOODWILL AND ACQUIRED INTANGIBLE ASSETS

Goodwill

Teradyne performs its annual goodwill impairment test as required under the provisions of ASC 350-10, “Intangibles—Goodwill and Other” on December 31 of each fiscal year unless interim indicators of impairment exist. Goodwill is considered impaired when the net book value of a reporting unit exceeds its estimated fair value.

The changes in the carrying amount of goodwill by reportable segments for the six months ended July 1, 2018, were as follows:


	Wireless Test			Industrial Automation			System Test			Semiconductor Test			Total
	(in thousands)
Balance at December 31, 2017
Goodwill	$	361,819		$	233,519		$	158,699		$	260,540		$	1,014,577
Accumulated impairment losses		(353,843	)		—			(148,183	)		(260,540	)		(762,566	)

		7,976			233,519			10,516			—			252,011
MiR acquisition		—			135,747			—			—			135,747
Energid acquisition		—			14,394			—			—			14,394
Foreign currency translation adjustment		—			(13,527	)		—			—			(13,527	)

Balance at July 1, 2018
Goodwill		361,819			370,133			158,699			260,540			1,151,191
Accumulated impairment losses		(353,843	)		—			(148,183	)		(260,540	)		(762,566	)

	$	7,976		$	370,133		$	10,516		$	—		$	388,625

Intangible Assets

Teradyne reviews long-lived assets for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable or that the useful lives of these assets are no longer appropriate.

Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheet:


	July 1, 2018
	Gross Carrying Amount (1)(2)		Accumulated Amortization (2)			Foreign Currency Translation Adjustment			Net Carrying Amount
	(in thousands)
Developed technology	$	341,227	$	(236,924	)	$	(2,687	)	$	101,616
Customer relationships		100,891		(86,509	)		(118	)		14,264
Tradenames and trademarks		63,240		(30,530	)		(437	)		32,273
Non-compete agreement		320		(300	)		—			20
Backlog		10		(10	)		—			—

Total intangible assets	$	505,688	$	(354,273	)	$	(3,242	)	$	148,173


	December 31, 2017
	Gross Carrying Amount		Accumulated Amortization			Foreign Currency Translation Adjustment		Net Carrying Amount
	(in thousands)
Developed technology	$	270,877	$	(226,190	)	$	1,618	$	46,305
Customer relationships		92,741		(83,585	)		171		9,327
Tradenames and trademarks		50,100		(27,120	)		416		23,396
Non-compete agreement		320		(260	)		—		60

Total intangible assets	$	414,038	$	(337,155	)	$	2,205	$	79,088

(1)	Includes intangible assets acquired in 2018, $79.7 million from the MiR acquisition and $12.3 million from the Energid acquisition.

(2)	In 2018, $0.3 million of amortizable intangible assets became fully amortized and have been eliminated from the gross carrying amount and accumulated amortization.

Aggregate intangible asset amortization expense was $9.8 million and $17.5 million, respectively, for the three and six months ended July 1, 2018 and $8.2 million and $16.1 million, respectively, for the three and six months ended July 2, 2017.

Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows:


Year	Amortization Expense
	(in thousands)
2018 (remainder)		20,856
2019		37,891
2020		23,671
2021		14,734
2022		13,841
Thereafter		37,180