Intangible Assets

9 Months Ended

Sep. 28, 2014

Intangible Assets

K. Intangible Assets

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

	September 28, 2014
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Weighted Average Useful Life
	(in thousands)
Developed technology	$	342,933	$	212,949	$	129,984		6.2 years
Customer relationships		141,005		90,244		50,761		8.0 years
Trade names and trademarks		30,034		13,302		16,732		9.1 years
Total intangible assets	$	513,972	$	316,495	$	197,477		6.9 years

	December 31, 2013
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Weighted Average Useful Life
	(in thousands)
Developed technology	$	342,933	$	174,563	$	168,370		6.2 years
Customer relationships		141,497		76,963		64,534		8.0 years
Trade names and trademarks		30,034		10,647		19,387		9.1 years
Customer backlog		1,000		1,000		—		0.4 years
Total intangible assets	$	515,464	$	263,173	$	252,291		6.9 years

Aggregate intangible asset amortization expense was $18.3 million and $54.8 million, respectively, for the three and nine months ended September 28, 2014 and $18.1 million and $54.2 million, respectively, for the three and nine months ended September 29, 2013. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows:

Year	Amortization Expense
	(in thousands)
2014 (remainder)	$	15,327
2015		53,391
2016		53,391
2017		47,232
2018		22,691
Thereafter		5,445