v3.10.0.1

Significant Accounting Policies (Details) - USD ($) $ in Thousands | 9 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Short-term Investments |  |  |
Short-term investments | $ 25,000 |  | $ 0
Non-Cash Long-Lived Asset Additions |  |  |
Capital asset additions during the period | 70,700 | $ 49,600 |
Non-cash capital expenditure | 6,100 | $ 12,300 |
Accounts payable and accrued expenses |  |  |
Marketing and Sales Costs |  |  |
Accrued marketing costs | $ 16,100 |  | $ 11,700
Minimum |  |  |
Amortizable Intangible Assets |  |  |
Useful life of capitalized content development costs | 4 years |  |
Maximum |  |  |
Amortizable Intangible Assets |  |  |
Useful life of capitalized content development costs | 5 years |  |
Graduate Program Segment | Minimum |  |  |
Performance Obligations |  |  |
Period of contract with university clients | 10 years |  |
Graduate Program Segment | Maximum |  |  |
Performance Obligations |  |  |
Period of contract with university clients | 15 years |  |
Short Course Segment | Minimum |  |  |
Performance Obligations |  |  |
Period of contract with university clients | 42 days |  |
Short Course Segment | Maximum |  |  |
Performance Obligations |  |  |
Period of contract with university clients | 112 days |  |

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