| Intangible Assets |
Intangible Assets Intangible assets consisted of the following at December 31, 2015 and December 31, 2014 (in thousands, except years): | | | | | | | | | | | | | | | | At December 31, 2015 | | Gross Carrying Value | | Accumulated Amortization | | Net Carrying Value | | Weighted average useful life in years | Acquired technology and domain name | $ | 31,090 |
| | $ | (13,835 | ) | | $ | 17,255 |
| | 9.70 | Customer relationships | 6,300 |
| | (3,252 | ) | | 3,048 |
| | 8.97 | Tradenames | 4,900 |
| | (1,388 | ) | | 3,512 |
| | 15.00 | Total | $ | 42,290 |
| | $ | (18,475 | ) | | $ | 23,815 |
| | 10.20 |
| | | | | | | | | | | | | | | | At December 31, 2014 | | Gross Carrying Value | | Accumulated Amortization | | Net Carrying Value | | Weighted average useful life in years | Acquired technology and domain name | $ | 31,090 |
| | $ | (10,788 | ) | | $ | 20,302 |
| | 9.70 | Customer relationships | 6,300 |
| | (2,491 | ) | | 3,809 |
| | 8.97 | Tradenames | 4,900 |
| | (1,062 | ) | | 3,838 |
| | 15.00 | Total | $ | 42,290 |
| | $ | (14,341 | ) | | $ | 27,949 |
| | 10.20 |
Amortization expense by asset type for the years ended December 31, 2015, 2014, and 2013 is shown below (in thousands): | | | | | | | | | | | | | | Year Ended December 31, | | 2015 | | 2014 | | 2013 | Acquired technology and domain name | $ | 3,047 |
| | $ | 3,164 |
| | $ | 3,318 |
| Customer relationships | 760 |
| | 760 |
| | 760 |
| Trade names | 327 |
| | 327 |
| | 327 |
| Total amortization | $ | 4,134 |
| | $ | 4,251 |
| | $ | 4,405 |
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Expected amortization expense with respect to intangible assets at December 31, 2015 for each of the five years through December 31, 2020 and thereafter is as follows (in thousands): | | | | | Years ended December 31, | | 2016 | $ | 4,041 |
| 2017 | 3,862 |
| 2018 | 3,861 |
| 2019 | 3,791 |
| 2020 | 3,787 |
| Thereafter | 4,473 |
| Total amortization expense | $ | 23,815 |
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