v3.8.0.1

Stock-Based Compensation (Tables) | 12 Months Ended
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Dec. 31, 2017
Stock options |
Stock-Based Compensation |
Schedule of stock-based compensation expense included in the consolidated statements of operations and comprehensive loss |
|  | Year Ended December 31, |
|  | 2017 |  | 2016 |  | 2015 |
|  | (in thousands) |
Curriculum and teaching |  | $ | 3 |  | $ | — |  | $ | — |
Servicing and support |  |  | 4,036 |  |  | 3,245 |  |  | 2,270 |
Technology and content development |  |  | 3,306 |  |  | 2,392 |  |  | 1,548 |
Marketing and sales |  |  | 1,742 |  |  | 1,317 |  |  | 1,057 |
General and administrative |  |  | 12,843 |  |  | 8,869 |  |  | 7,624 |
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Total stock-based compensation expense |  | $ | 21,930 |  | $ | 15,823 |  | $ | 12,499 |
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Summary assumptions used for estimating the fair value of the stock options granted |
|  | Year Ended December 31,
|  | 2017 |  | 2016 |  | 2015
Risk-free interest rate |  | 2.0% - 2.1% |  | 1.1% - 1.9% |  | 1.5% - 1.9%
Expected term (years) |  | 6.00 - 6.08 |  | 5.43 - 6.50 |  | 5.56 - 6.08
Expected volatility |  | 46% - 49% |  | 50% |  | 50%
Dividend yield |  | 0% |  | 0% |  | 0%
Summary of stock option activity |
|  | Number of Options |  | Weighted-Average Exercise Price per Share |  | Weighted-Average Remaining Contractual Term (in years) |  | Aggregate Intrinsic Value (in thousands) |
Outstanding balance at December 31, 2016 |  |  | 4,882,237 |  | $ | 10.74 |  |  | 6.30 |  | $ | 95,081 |
Granted |  |  | 605,640 |  |  | 40.90 |  |  | 8.95 |  |  |  |
Exercised |  |  | (846,821 | ) |  | 7.81 |  |  | 3.97 |  |  |  |
Forfeited |  |  | (65,853 | ) |  | 23.63 |  |  |  |  |  |  |
Expired |  |  | (16,027 | ) |  | 13.26 |  |  |  |  |  |  |
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Outstanding balance at December 31, 2017 |  |  | 4,559,176 |  |  | 15.10 |  |  | 5.88 |  |  | 225,283 |
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Exercisable at December 31, 2017 |  |  | 3,357,682 |  |  | 8.96 |  |  | 4.92 |  |  | 186,529 |
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Vested and expected to vest at December 31, 2017 |  |  | 4,559,176 |  |  | 15.10 |  |  | 5.88 |  |  | 225,283 |
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Restricted Stock Units |
Stock-Based Compensation |
Summary of restricted stock unit activity |
|  | Number of Restricted Stock Units |  | Weighted-Average Grant Date Fair Value per Share |
Outstanding balance at December 31, 2016 |  |  | 1,412,934 |  | $ | 20.60 |
Granted |  |  | 620,259 |  |  | 41.74 |
Vested |  |  | (494,504 | ) |  | 18.98 |
Forfeited |  |  | (125,266 | ) |  | 26.16 |
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Outstanding balance at December 31, 2017 |  |  | 1,413,423 |  |  | 29.95 |
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- Definition Tabular disclosure of the allocation of equity-based compensation costs to a given line item on the balance sheet and income statement for the period. This may include the reporting line for the costs and the amount capitalized and expensed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 + Details
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- Definition Tabular disclosure of the number and weighted-average grant date fair value for restricted stock units that were outstanding at the beginning and end of the year, and the number of restricted stock units that were granted, vested, or forfeited during the year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=96867065&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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
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