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Share Based Payments - Additional Information (Details) $ / shares in Units, $ in Millions |  |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Aug. 08, 2018 USD ($) | Apr. 01, 2018 USD ($) | Dec. 31, 2017 shares | Jun. 30, 2017 | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2017 $ / shares shares | May 15, 2018 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Common stock shares available for issuance |  |  |  |  |  |  | 3,000,000
Number of stock option issued |  |  |  |  | 1,011,406 | 868,902 |
Stock option forfeited |  |  |  |  | 53,503 | 153,067 |
Fair value of options recorded in stock based compensation liability | $ |  | $ 10.0 |  |  |  |  |
Reclassification of equity-classified stock options to stock-based compensation liability due to change in functional currency | $ |  | $ 4.2 |  |  |  |  |
Reduction to stock-based compensation liability | $ | $ 0.3 |  |  |  |  |  |
Reclassified from liability to equity | $ | $ 10.3 |  |  |  |  |  |
Weighted average exercise price | (per share) |  |  |  |  | $ 10.12 | $ 11.15 |
Employee and Director Stock Options |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Number of stock option issued |  |  |  |  | 996,406 | 673,902 |
Stock option forfeited |  |  |  |  | 53,503 |  |
Unrecognized compensation cost related to non-vested stock options outstanding | $ |  |  |  |  | $ 8.3 |  |
Weighted-average remaining vesting period |  |  |  |  | 3 years |  |
Weighted average exercise price | (per share) |  |  |  |  | $ 10.12 | $ 10.87 |
Weighted average grant date fair value | (per share) |  |  |  |  | $ 7.78 | $ 4.34 |
Consultants Stock Option |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Number of stock option issued |  |  |  |  | 15,000 | 195,000 |
Unrecognized compensation cost related to non-vested stock options outstanding | $ |  |  |  |  | $ 0.1 |  |
Weighted-average remaining vesting period |  |  |  |  | 2 years 7 months 6 days |  |
Weighted average exercise price | (per share) |  |  |  |  | $ 10.23 | $ 12.20 |
Weighted average grant date fair value | (per share) |  |  |  |  | $ 8.87 | $ 3.88 |
2018 Omnibus Incentive Plan |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Common stock shares authorized and approved to issue under plan |  |  |  |  |  |  | 5,356,114
Common stock remaining available for grant |  |  |  |  | 4,775,711 |  |
2016 Omnibus Incentive Plan |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Common stock shares available for issuance |  |  |  |  |  |  | 2,356,114
2016 Omnibus Incentive Plan | Common Stock |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Aggregate amount of stock excess award |  |  | 60,000 |  |  |  |
2016 Omnibus Incentive Plan | Restricted Stock Units |  |  |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |  |  |
Vesting period |  |  |  | 3 years |  |  |
Vesting percentage |  |  |  | 25.00% |  |  |

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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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