| Schedule of Finite Lived Intangible Assets |
The changes to the carrying value of intangible assets were as follows (in thousands):
| | | | | | | | | | | | | | | | | | Three Months Ended September 30, | | Nine Months Ended September 30, | | 2019 | | 2018 | | 2019 | | 2018 | Acquired intangible assets, net, beginning of the period | $ | 84,216 |
| | $ | 85,514 |
| | $ | 77,102 |
| | $ | 14,334 |
| Acquisitions | — |
| | — |
| | 14,559 |
| | 75,871 |
| Amortization expense | (3,841 | ) | | (4,384 | ) | | (11,286 | ) | | (9,075 | ) | Transfer to assets held for sale (Note 8) | (7,582 | ) | | — |
| | (7,582 | ) | | — |
| Acquired intangible assets, net, end of the period | $ | 72,793 |
| | $ | 81,130 |
| | $ | 72,793 |
| | $ | 81,130 |
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The following table presents the detail of acquired intangible assets as of the periods presented (in thousands): | | | | | | | | | | | | | | Balance at September 30, 2019 | Cost | | Accumulated Amortization | | Net | Technology assets | 54,630 |
| | (30,682 | ) | | 23,948 |
| Customer assets | 44,045 |
| | (6,089 | ) | | 37,956 |
| Trade name | 11,300 |
| | (3,767 | ) | | 7,533 |
| Other | 5,299 |
| | (1,943 | ) | | 3,356 |
| Total | $ | 115,274 |
| | $ | (42,481 | ) | | $ | 72,793 |
|
| | | | | | | | | | | | | | Balance at December 31, 2018 | Cost | | Accumulated Amortization | | Net | Technology assets | $ | 45,978 |
| | $ | (28,420 | ) | | $ | 17,558 |
| Customer assets | 57,109 |
| | (8,068 | ) | | 49,041 |
| Trade name | 11,300 |
| | (1,648 | ) | | 9,652 |
| Other | 2,246 |
| | (1,395 | ) | | 851 |
| Total | $ | 116,633 |
| | $ | (39,531 | ) | | $ | 77,102 |
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| Schedule of Future Amortization Expense of Intangible Assets |
The total estimated future amortization expense of these intangible assets as of September 30, 2019 is as follows (in thousands): | | | | | 2019 (remaining 3 months) | $ | 3,714 |
| 2020 | 12,800 |
| 2021 | 11,829 |
| 2022 | 10,134 |
| 2023 | 8,917 |
| Thereafter | 25,399 |
| Total | $ | 72,793 |
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