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Share-Based Compensation (Tables)
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9 Months Ended |
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Sep. 30, 2012
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| Share-Based Compensation [Abstract] |
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| Share-based compensation expense recognized in the accompanying Consolidated Statements of Operations and Comprehensive Loss |
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Three Months Ended September 30, |
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Nine Months Ended September 30, |
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Cumulative
from
April 20, 2009
(Inception) to
September 30,
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2012 |
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2011 |
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2012 |
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2011 |
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2012 |
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Research and development
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$ |
687 |
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$ |
192 |
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$ |
1,719 |
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$ |
398 |
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$ |
2,380 |
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General and administrative
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807 |
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213 |
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1,889 |
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404 |
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2,625 |
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Total share-based compensation expense
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$ |
1,494 |
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$ |
405 |
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$ |
3,608 |
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$ |
802 |
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$ |
5,005 |
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| Summary of stock options activity |
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Option Shares
Outstanding |
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Weighted-
Average
Exercise
Price |
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Weighted-
Average
Remaining
Contractual
Term (Years) |
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Aggregate
Intrinsic
Value |
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Balance at December 31, 2011
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934,816 |
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$ |
4.88 |
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Granted
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813,198 |
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23.57 |
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Exercised
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(13,510 |
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3.12 |
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Forfeited
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(21,306 |
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9.07 |
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Balance at September 30, 2012
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1,713,198 |
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$ |
13.71 |
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8.79 |
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$ |
14,294,555 |
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Vested and expected to vest at September 30, 2012
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1,566,755 |
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$ |
13.11 |
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8.74 |
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$ |
13,843,903 |
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Vested at September 30, 2012
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499,338 |
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$ |
3.99 |
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7.91 |
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$ |
8,218,956 |
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| Schedule of share-based compensation arrangements by share-based payment award |
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Three Months Ended September 30, |
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2012 |
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2011 |
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Weighted-average grant-date fair value per share
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$ |
14.32 |
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$ |
7.11 |
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Intrinsic value of options exercised
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$ |
— |
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$ |
404,648 |
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Cash received from stock option exercises
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$ |
— |
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$ |
162,518 |
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Nine Months Ended September 30, |
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2012 |
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2011 |
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Weighted-average grant-date fair value per share
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$ |
15.01 |
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$ |
8.71 |
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Intrinsic value of options exercised
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$ |
223,319 |
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$ |
409,742 |
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Cash received from stock option exercises
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$ |
42,149 |
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$ |
1,050,873 |
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| Unrecognized share-based compensation expense |
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Unrecognized share-based
compensation expense
(in millions)
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Weighted- average
remaining vesting period
(in years)
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$ 13.3
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3.0 |
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