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Stock incentive plans (Details 5) (Unvested stock option, USD $)
In Thousands, unless otherwise specified |
12 Months Ended |
|---|---|
|
Dec. 31, 2014
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Unvested stock option
|
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| Stock incentive plans | |
| Total stock-based compensation expense | $ 4,479 |
| Weighted average period over which unrecognized compensation expense is expected to be recognized | 2 years 1 month 10 days |