Intangible Assets

3 Months Ended

Mar. 30, 2014

Intangible Assets

K. Intangible Assets

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

	March 30, 2014
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Weighted Average Useful Life
	(in thousands)
Developed technology	$	362,126	$	206,551	$	155,575		6.3 years
Customer relationships		146,276		86,333		59,943		8.0 years
Trade names and trademarks		33,834		15,332		18,502		9.0 years
Customer backlog		1,000		1,000		—		0.4 years
Total intangible assets	$	543,236	$	309,216	$	234,020		7.0 years

	December 31, 2013
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Weighted Average Useful Life
	(in thousands)
Developed technology	$	362,126	$	193,756	$	168,370		6.3 years
Customer relationships		146,276		81,742		64,534		8.0 years
Trade names and trademarks		33,834		14,447		19,387		9.0 years
Customer backlog		1,000		1,000		—		0.4 years
Total intangible assets	$	543,236	$	290,945	$	252,291		7.0 years

Aggregate intangible asset amortization expense was $18.3 million and $18.0 million, respectively, for the three months ended March 30, 2014 and March 31, 2013. Estimated intangible asset amortization expense for each of the five succeeding fiscal years is as follows:

Year	Amortization Expense
	(in thousands)
2014 (remainder)	$	51,870
2015		53,391
2016		53,391
2017		47,232
2018		22,691