Goodwill and Other Intangible Assets

The amounts for goodwill and changes in the carrying value by segment for the nine months ended September 29, 2018 are as follows:



(in thousands)	Electronics			Automotive			Industrial			Total
As of December 30, 2017	$	278,959		$	135,829		$	38,626		$	453,414
Additions(a)	380,199			—			—			380,199
Currency translation	(1,090		)	(2,040		)	(129		)	(3,259		)
As of September 29, 2018	$	658,068		$	133,789		$	38,497		$	830,354

(a)The additions resulted from the acquisition of IXYS and an immaterial acquisition.

The components of other intangible assets at September 29, 2018 are as follows:



(in thousands, except weighted average useful life)	Weighted Average Useful Life (Years)	Gross Carrying Value		Accumulated Amortization		Net Book Value
Patents, licenses and software	10.5	$	192,215	$	71,451	$	120,764
Distribution network	12.6	44,098		34,214		9,884
Customer relationships, trademarks, and tradenames	18	312,267		69,478		242,789
Order backlog	0.3	12,420		8,706		3,714
Total		$	561,000	$	183,849	$	377,151

During the nine months ended September 29, 2018, the Company recorded additions to other intangible assets of $212.7 million, related to the IXYS acquisition, the components of which were as follows:



(in thousands, except weighted average useful life)	Weighted Average Useful Life (Years)	Amount
Patents, licenses and software	8	$	51,500
Customer relationships, trademarks, and tradenames	17.2	148,800
Order backlog	1	12,420
Total		$	212,720

During the three and nine months ended September 29, 2018 and September 30, 2017, the Company recorded amortization expense of $13.1 million and $38.5 million and $6.3 million and $18.4 million, respectively, for intangible assets with definite lives.

Estimated annual amortization expense related to intangible assets with definite lives as of September 29, 2018 is as follows:



(in thousands)	Amount
2018	$	53,383
2019	40,454
2020	40,237
2021	38,403
2022	37,506
2023 and thereafter	206,586
Total	$	416,569