STOCK-BASED COMPENSATION (Tables)
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12 Months Ended |
Dec. 31, 2016 |
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| STOCK-BASED COMPENSATION |
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| Schedule of stock-based compensation expense related to all of the entity's share-based awards |
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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2016
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2015
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2014
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General and administrative
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$
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4,230
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$
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3,303
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$
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5,113
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Research and development
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3,103
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4,100
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4,674
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Restructuring charges
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499
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—
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—
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Total stock-based compensation expense
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$
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7,832
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$
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7,403
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$
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9,787
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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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2016
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2015
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2014
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Risk-free interest rate
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1.8
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%
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1.8
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%
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2.2
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%
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Expected term (in years)
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6.2
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6.5
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6.5
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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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61.1
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%
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65.0
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%
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74.4
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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, 2016
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5,245,977
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19,106,472
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$
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7.08
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Authorized for grant
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2,790,000
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—
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Granted
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(5,251,185)
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5,251,185
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$
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2.98
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Exercised
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—
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(336,520)
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$
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2.30
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Cancelled
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3,763,904
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(3,763,904)
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$
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6.32
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Outstanding at December 31, 2016
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6,548,696
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20,257,233
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$
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6.24
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5.04
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$
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727,727
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Vested and expected to vest at December 31, 2016
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20,032,758
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$
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6.27
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Exercisable at December 31, 2016
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16,588,341
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$
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6.93
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4.11
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$
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696,655
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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, 2016:
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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 - $2.54
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3,638,849
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6.65
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$
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2.20
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3,036,017
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$
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2.15
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$2.72 - $3.20
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3,387,562
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7.41
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2.86
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1,822,751
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2.95
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$3.26 - $3.92
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3,505,077
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7.11
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3.65
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2,010,617
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3.57
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$3.96 - $6.55
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3,551,425
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3.67
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6.33
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3,544,637
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6.33
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$6.73 - $9.62
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4,270,760
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3.17
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8.06
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4,270,760
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8.06
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$9.74 - $26.45
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1,903,560
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0.70
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20.49
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1,903,560
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20.49
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$1.68 - $26.45
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20,257,233
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5.04
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6.24
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16,588,342
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6.93
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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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2016
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2015
|
|
2014
|
|
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Risk-free interest rate
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0.5
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%
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0.6
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%
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0.3
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%
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Expected term (in years)
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1.5
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1.5
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1.7
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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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62.9
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%
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61.2
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%
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66.0
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%
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