| Schedule of changes in goodwill |
The table below summarizes the changes in the carrying amount of goodwill by reportable segment: | | | | | | | | | | | | | | Graduate Program Segment | | Short Course Segment | | Total | | (in thousands) | Balance as of December 31, 2017 | $ | — |
| | $ | 71,988 |
| | $ | 71,988 |
| Foreign currency translation adjustments | — |
| | (9,033 | ) | | (9,033 | ) | Balance as of September 30, 2018 | $ | — |
|
| $ | 62,955 |
|
| $ | 62,955 |
|
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| Schedule of amortizable intangible assets |
Amortizable intangible assets consisted of the following as of: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | September 30, 2018 | | December 31, 2017 | | Estimated Average Useful Life (in years) | | Gross Carrying Amount | | Accumulated Amortization | | Net Carrying Amount | | Gross Carrying Amount | | Accumulated Amortization | | Net Carrying Amount | | (in thousands) | Capitalized technology | 3-5 | | $ | 63,789 |
| | $ | (14,593 | ) | | $ | 49,196 |
| | $ | 27,108 |
| | $ | (9,486 | ) | | $ | 17,622 |
| Capitalized content development | 4-5 | | 73,428 |
| | (28,758 | ) | | 44,670 |
| | 55,872 |
| | (21,417 | ) | | 34,455 |
| University client relationships | 9 | | 26,033 |
| | (3,616 | ) | | 22,417 |
| | 29,443 |
| | (1,636 | ) | | 27,807 |
| Trade names and domain names | 10 | | 16,852 |
| | (2,443 | ) | | 14,409 |
| | 12,119 |
| | (1,242 | ) | | 10,877 |
| Total amortizable intangible assets, net | | | $ | 180,102 |
| | $ | (49,410 | ) | | $ | 130,692 |
| | $ | 124,542 |
| | $ | (33,781 | ) | | $ | 90,761 |
|
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| Schedule of estimated future amortization expense for amortizable intangible assets |
As of September 30, 2018, the estimated future amortization expense for amortizable intangible assets placed in service is as follows (in thousands): | | | | | Remainder of 2018 | $ | 6,094 |
| 2019 | 23,015 |
| 2020 | 19,996 |
| 2021 | 15,503 |
| 2022 | 11,688 |
| Thereafter | 22,043 |
| Total | $ | 98,339 |
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