STOCK-BASED COMPENSATION (Tables)
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12 Months Ended |
Dec. 31, 2018 |
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| STOCK-BASED COMPENSATION |
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| Schedule of stock-based compensation related to all of the entity's share-based payments |
Total stock‑based compensation expense related to all of our stock‑based awards was as follows (in thousands):
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Year Ended December 31,
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2018
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2017
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2016
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Selling, general and administrative
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$
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5,383
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$
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4,490
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$
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4,230
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Research and development
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2,321
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1,497
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3,103
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Restructuring charges
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—
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—
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499
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Total stock-based compensation expense
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$
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7,704
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$
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5,987
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$
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7,832
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| Summary of weighted-average assumptions relating to options granted pursuant to equity incentive plans |
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Year Ended
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December 31,
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2018
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2017
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2016
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Risk-free interest rate
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2.7
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%
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2.2
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%
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1.8
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%
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Expected term (in years)
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6.7
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6.6
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6.2
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Dividend yield
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0.0
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%
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0.0
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%
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0.0
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%
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Expected volatility
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65.1
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%
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63.5
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%
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61.1
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%
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| Schedule of option activity under equity incentive plans |
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Weighted-
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Average
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Remaining
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Shares Available
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Number of Shares
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Weighted-Average
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Contractual Term
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Aggregate
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For Grant
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Underlying Options
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Exercise Price
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(in years)
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Intrinsic Value
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Outstanding at January 1, 2018
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11,696,696
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20,408,140
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$
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5.45
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Authorized for grant
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4,878,124
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—
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Granted
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(4,594,225)
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4,594,225
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$
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4.19
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Exercised
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—
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(1,172,615)
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$
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2.75
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Cancelled
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3,116,419
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(3,116,419)
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$
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12.87
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Outstanding at December 31, 2018
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15,097,014
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20,713,331
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$
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4.20
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5.96
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$
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701,842
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Vested and expected to vest at December 31, 2018
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20,513,331
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$
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4.21
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Exercisable at December 31, 2018
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14,750,561
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$
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4.39
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4.84
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$
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580,787
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| Schedule of stock options by exercise price |
Details of our stock options by exercise price are as follows as of December 31, 2018:
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Options Outstanding
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Options Exercisable
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Number of
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Weighted-Average
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Outstanding
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Remaining
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Weighted-Average
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Number of
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Weighted-Average
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Exercise Price
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Options
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Contractual Life (in years)
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Exercise Price
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Options
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Exercise Price
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$1.68 - $2.14
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3,879,555
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6.68
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$
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2.12
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3,278,782
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$
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2.12
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$2.15 - $2.76
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3,344,004
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6.92
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2.61
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2,756,548
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2.65
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$2.77 - $3.67
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3,532,086
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6.12
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3.49
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2,433,716
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3.48
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$3.68 - $4.49
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4,893,668
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8.79
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4.25
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1,217,498
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4.10
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$4.50 - $7.60
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3,326,279
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1.94
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6.57
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3,326,279
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6.57
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$7.61 - $9.80
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1,737,739
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1.97
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8.71
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1,737,739
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8.71
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$1.68 - $9.80
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20,713,331
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5.96
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4.20
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14,750,562
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4.39
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| Summary of weighted-average assumptions used to calculate fair value of purchase rights granted under Employee Stock Purchase Plan |
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Year Ended
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December 31,
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2018
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2017
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|
2016
|
|
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Risk-free interest rate
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2.4
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%
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0.5
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%
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0.5
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%
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Expected term (in years)
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1.3
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1.5
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1.5
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Dividend yield
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0.0
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%
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0.0
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%
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0.0
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%
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Expected volatility
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66.2
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%
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63.1
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%
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62.9
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%
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