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Stock Compensation (Details) (USD $)
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12 Months Ended |
0 Months Ended |
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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Jun. 25, 2013
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| Number of Options |
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| Outstanding at the beginning of period (in shares) |
1,401,101 |
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|
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| Granted (in shares) |
561,500 |
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|
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| Forfeited or expired (vested and unvested) (in shares) |
(125,052) |
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|
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| Exercised (in shares) |
(107,963) |
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|
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| Outstanding at the end of the period (in shares) |
1,729,586 |
1,401,101 |
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| Weighted-Average Price Per Share |
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| Outstanding at the beginning of period (in dollars per share) |
$ 9.59 |
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|
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| Granted (in dollars per share) |
$ 15.03 |
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| Forfeited or expired (vested and unvested) (in dollars per share) |
$ 12.97 |
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|
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| Exercised (in dollars per share) |
$ 4.38 |
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| Outstanding at the end of the period (in dollars per share) |
$ 11.44 |
$ 9.59 |
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| Weighted-Average Remaining Contractual Term (Years) |
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| Outstanding at the end of the period |
8 years 5 months 5 days |
8 years 11 months 12 days |
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| Aggregate Intrinsic Value |
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| Outstanding at the end of the period (in dollars) |
$ 50,155,000 |
$ 7,755,000 |
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| Information about the stock option plan |
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| Number of Options, vested and expected to vest (in shares) |
1,671,313 |
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| Number of Options, exercisable (in shares) |
752,397 |
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| Weighted-Average Price Per Share, vested and expected to vest (in dollars per share) |
$ 11.37 |
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| Weighted-Average Price Per Share, exercisable (in dollars per share) |
$ 6.61 |
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| Weighted-Average Remaining Contractual Term, vested and expected to vest |
8 years 4 months 28 days |
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| Weighted-Average Remaining Contractual Term, exercisable |
7 years 6 months 29 days |
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| Aggregate Intrinsic Value, vested and expected to vest (in dollars) |
48,588,000 |
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| Aggregate Intrinsic Value, exercisable (in dollars) |
25,452,000 |
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| Total intrinsic value of stock options exercised |
1,400,000 |
200,000 |
100,000 |
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| Additional disclosures |
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| Unrecognized compensation cost (in dollars) |
9,300,000 |
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| Weighted-average period over which remaining unrecognized compensation cost will be recognized |
2 years 10 months 24 days |
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| Weighted-average grant-date fair value (in dollars per share) |
$ 10.15 |
$ 7.14 |
$ 1.33 |
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| Stock-based compensation expense |
$ 3,700,000 |
$ 1,200,000 |
$ 100,000 |
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| Assumptions used to compute the share-based compensation costs for stock options granted to employees and non-employees |
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|
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| Risk-free interest rate (as a percent) |
1.81% |
1.45% |
0.85% |
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| Weighted-average expected life of options (years) |
6 years 3 months 26 days |
6 years 3 months 4 days |
6 years 3 months |
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| Volatility (as a percent) |
75.00% |
74.00% |
80.00% |
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| 2013 Stock Option and Incentive Plan |
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| Stock compensation |
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| Shares reserved and approved for issuance |
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|
1,100,000 |
| Shares reserved under previous plan and subsequently transferred to new plan |
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|
54,129 |
| Percentage of increase in the number of shares reserved and available for issuance |
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|
2.50% |
| 2008 Incentive Stock Option and Restricted Stock Plan |
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| Stock compensation |
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| Shares reserved under previous plan and subsequently transferred to new plan |
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|
54,129 |
| Expiration period |
10 years |
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| Period from cessation of employment within which options expire if not exercised |
90 days |
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| Grant period of stock awards |
10 years |
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| Purchase price expressed as a percentage of fair value of shares on the date of grant |
100.00% |
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| Vesting percentage on the first anniversary of the option grant |
25.00% |
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| Period for which remainder of grant amount will vest on the first day of each calendar quarter |
3 years |
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