GOODWILL AND IDENTIFIED INTANGIBLE ASSETS

The changes to the carrying value of goodwill from January 1, 2018 through June 30, 2018 are reflected below (in thousands):



December 31, 2017	$	385,574
Goodwill acquired through a business acquisition (1)	210
June 30, 2018	$	385,784	(2	)

(1) Related to the acquisition of an emerging technology company in May 2018.

(2) Of this amount, approximately $378.1 million was allocated to the Product Licensing segment and approximately $7.7 million was allocated to the Semiconductor and IP Licensing segment.

Identified intangible assets consisted of the following (in thousands):



		June 30, 2018							December 31, 2017
	Average Life (Years)	Gross Assets		Accumulated Amortization			Net		Gross Assets		Accumulated Amortization			Net
Acquired patents / core technology	3-15	$	142,934	$	(121,275	)	$	21,659	$	142,584	$	(113,349	)	$	29,235
Existing technology	5-10	206,879		(78,689		)	128,190		204,394		(61,518		)	142,876
Customer contracts and related relationships	3-9	291,769		(95,049		)	196,720		291,769		(68,267		)	223,502
Trademarks/trade name	4-10	40,083		(8,597		)	31,486		40,083		(6,111		)	33,972
Non-competition agreements	1	2,231		(2,231		)	—		2,231		(2,231		)	—
Total amortizable intangible assets		683,896		(305,841		)	378,055		681,061		(251,476		)	429,585
In-process research and development		—		—			—		2,204		—			2,204
Total intangible assets		$	683,896	$	(305,841	)	$	378,055	$	683,265	$	(251,476	)	$	431,789

Amortization expense for the three months ended June 30, 2018 and 2017 amounted to $27.2 million and $28.2 million, respectively.

Amortization expense for the six months ended June 30, 2018 and 2017 amounted to $54.4 million and $56.7 million, respectively.

As of June 30, 2018, the estimated future amortization expense of total intangible assets was as follows (in thousands):



2018 (remaining 6 months)	$	53,921
2019	99,383
2020	87,668
2021	80,006
2022	31,614
Thereafter	25,463
	$	378,055