v3.19.3.a.u2

Stock-Based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2019
Stock-Based Compensation |
Schedule of stock-based compensation expense related to stock-based awards | Stock-based compensation expense related to stock-based awards, as well as the ESPP, is included in the following line items on the accompanying consolidated statements of operations and comprehensive loss:
| Year Ended December 31,
| 2019 |  | 2018 |  | 2017
| (in thousands)
Curriculum and teaching | $ | 45 |  |  | $ | 14 |  |  | $ | 3 |
Servicing and support | 8,915 |  |  | 4,764 |  |  | 4,036 |
Technology and content development | 8,241 |  |  | 4,094 |  |  | 3,306 |
Marketing and sales | 7,021 |  |  | 2,743 |  |  | 1,742 |
General and administrative | 27,282 |  |  | 19,795 |  |  | 12,843 |
Total stock-based compensation expense | $ | 51,504 |  |  | $ | 31,410 |  |  | $ | 21,930 |
Stock options |
Stock-Based Compensation |
Schedule of assumptions used for estimating the fair value of the stock options granted | The following table summarizes the assumptions used for estimating the fair value of the stock options granted for the periods presented.
| Year Ended December 31,
| 2019 |  | 2018 |  | 2017
Risk-free interest rate | 1.6% - 2.6% |  | 2.3% - 3.0% |  | 2.0% - 2.1%
Expected term (years) | 5.96 - 6.08 |  | 5.97 - 6.77 |  | 6.00 - 6.08
Expected volatility | 45% - 64% |  | 44% - 45% |  | 46% - 49%
Dividend yield | 0% |  | 0% |  | 0%
Schedule of stock option activity | The following is a summary of the stock option activity for the year ended December 31, 2019:
| Number of Options |  | Weighted-Average Exercise Price per Share |  | Weighted-Average Remaining Contractual Term (in years) |  | Aggregate Intrinsic Value (in thousands)
Outstanding balance as of December 31, 2018 | 4,057,788 |  |  | $ | 27.23 |  |  | 5.95 |  | $ | 113,211 |
Granted | 809,289 |  |  | 61.34 |  |  | 8.35 |  |  |
Exercised | (361,134 | ) |  | 8.64 |  |  | 1.36 |  |  |
Forfeited | (116,435 | ) |  | 56.00 |  |  |  |  |  |
Expired | (15,613 | ) |  | 44.99 |  |  |  |  |  |
Outstanding balance as of December 31, 2019 | 4,373,895 |  |  | 34.24 |  |  | 5.88 |  | 28,736 |
Exercisable as of December 31, 2019 | 3,051,658 |  |  | $ | 20.98 |  |  | 4.69 |  | $ | 28,374 |
Restricted stock units |
Stock-Based Compensation |
Schedule of restricted stock unit activity | The following is a summary of RSU and PRSU activity for the year ended December 31, 2019:
| Number of Restricted Stock Units |  | Weighted-Average Grant Date Fair Value per Share
Outstanding balance as of December 31, 2018 | 1,139,045 |  |  | $ | 52.47 |
Granted | 3,388,919 |  |  | 32.50 |
Vested | (538,752 | ) |  | 42.74 |
Forfeited | (294,297 | ) |  | 50.15 |
Outstanding balance as of December 31, 2019 | 3,694,915 |  |  | $ | 35.76 |

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- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901 + Details
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