Amortizable intangible assets consist of the following and are included in intangible assets, net on the balance sheets:
| December 31, 2013 | ||||||||||||||||
| Gross Carrying Amount |
Accumulated Amortization |
Net Carrying Amount |
Weighted Average Useful Life |
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| (in thousands) | ||||||||||||||||
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Developed technology |
$ | 362,055 | $ | 193,756 | $ | 168,299 | 6.3 years | |||||||||
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Customer relationships |
146,341 | 81,742 | 64,599 | 8.0 years | ||||||||||||
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Tradenames and trademarks |
33,840 | 14,447 | 19,393 | 9.0 years | ||||||||||||
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Customer backlog |
1,000 | 1,000 | — | 0.4 years | ||||||||||||
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Total intangible assets |
$ | 543,236 | $ | 290,945 | $ | 252,291 | 7.0 years | |||||||||
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| December 31, 2012 | ||||||||||||||||
| Gross Carrying Amount |
Accumulated Amortization |
Net Carrying Amount |
Weighted Average Useful Life |
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| (in thousands) | ||||||||||||||||
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Developed technology |
$ | 357,555 | $ | 143,126 | $ | 214,429 | 6.3 years | |||||||||
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Customer relationships |
144,971 | 63,464 | 81,507 | 8.0 years | ||||||||||||
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Tradenames and trademarks |
33,840 | 10,909 | 22,931 | 9.0 years | ||||||||||||
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Customer backlog |
1,000 | 1,000 | — | 0.4 years | ||||||||||||
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Total intangible assets |
$ | 537,366 | $ | 218,499 | $ | 318,867 | 7.0 years | |||||||||
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