Employee Benefit Plans - Assumptions For Estimating Fair Value (Details) - USD ($)
$ in Millions |
12 Months Ended |
|
|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Jul. 23, 2014 |
May 12, 2011 |
| Employee Benefit Plans |
|
|
|
|
|
| Compensation cost |
$ 9.0
|
$ 7.5
|
$ 3.6
|
|
|
| Stock options granted |
3,702,500
|
3,960,000
|
4,245,000
|
|
|
| Minimum |
|
|
|
|
|
| Assumptions for estimating fair value |
|
|
|
|
|
| Risk free rate (as a percent): |
1.27%
|
1.52%
|
1.77%
|
|
|
| Volatility (as a percent): |
103.87%
|
104.03%
|
107.17%
|
|
|
| Maximum |
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|
|
|
|
| Assumptions for estimating fair value |
|
|
|
|
|
| Risk free rate (as a percent): |
1.69%
|
1.87%
|
1.94%
|
|
|
| Volatility (as a percent): |
104.88%
|
105.29%
|
113.92%
|
|
|
| Stock options |
|
|
|
|
|
| Employee Benefit Plans |
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|
|
|
|
| Number of options outstanding (in shares) |
14,760,054
|
11,700,786
|
|
|
|
| Compensation cost |
$ 9.0
|
$ 7.5
|
$ 3.4
|
|
|
| Stock options granted |
3,702,500
|
3,960,000
|
4,246,000
|
|
|
| Assumptions for estimating fair value |
|
|
|
|
|
| Expected term of options (years) |
6 years
|
6 years
|
6 years
|
|
|
| the 2011 Plan | Stock options |
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|
|
|
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| Employee Benefit Plans |
|
|
|
|
|
| Maximum number of common stock shares available for issuance |
|
|
|
17,000,000
|
1,000,000
|
| Aggregate number of options granted (in shares) |
14,800,000
|
|
|
|
|
| Number of options outstanding (in shares) |
14,800,000
|
|
|
|
|
| Number of options available for issuance (in shares) |
1,000,000
|
|
|
|
|
| Expiration period |
10 years
|
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| the 2011 Plan | Stock options | Minimum |
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|
|
|
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| Employee Benefit Plans |
|
|
|
|
|
| Vesting period |
1 year
|
|
|
|
|
| the 2011 Plan | Stock options | Maximum |
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|
|
|
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| Employee Benefit Plans |
|
|
|
|
|
| Vesting period |
3 years
|
|
|
|
|
| the 2011 Plan | Employees | Stock options |
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|
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| Employee Benefit Plans |
|
|
|
|
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| Vesting period |
3 years
|
|
|
|
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| Expiration period |
10 years
|
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|
| the 2011 Plan | Board of Directors | Stock options |
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| Employee Benefit Plans |
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|
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| Vesting period |
1 year
|
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