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Stock-Based Compensation Plans (Narrative) (Details) | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2019 USD ($) plan shares | Jun. 30, 2018 USD ($) | Jun. 30, 2019 USD ($) plan shares | Jun. 30, 2018 USD ($) | Dec. 31, 2018 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Compensation expense for share-based payments | $ 5,200,045 | $ 4,465,634 | $ 9,986,839 | $ 8,366,949 |
Compensation cost capitalized as part of inventory |  |  | 319,080 |  | $ 242,673
Employee Stock Option Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost | $ 7,397,810 |  | $ 7,397,810 |  |
Employee Stock Option Plan | Minimum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Option vesting period |  |  | 1 year |  |
Option expiration period |  |  | 5 years |  |
Employee Stock Option Plan | Maximum |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Option vesting period |  |  | 5 years |  |
Option expiration period |  |  | 10 years |  |
Employee Stock Purchase Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Shares approved (in shares) | shares | 2,000,000 |  | 2,000,000 |  |
ESPP discount rate |  |  | 85.00% |  |
ESPP discount rate recognized as compensation expense |  |  | 15.00% |  |
Shares granted (in shares) | shares | 1,063,052 |  | 1,063,052 |  |
Restricted Stock Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost | $ 43,851,893 |  | $ 43,851,893 |  |
Restricted period, maximum, in years |  |  | 10 years |  |
Amortization expense | $ 3,274,411 | 2,189,938 | $ 6,046,175 | 3,832,998 |
Omnibus Incentive Plan |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of shares authorized (in shares) | shares | 45,000,000 |  | 45,000,000 |  |
Restricted period, maximum, in years |  |  | 3 years |  |
Equity Incentive Plans |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Number of plans | plan | 2 |  | 2 |  |
Performance Shares |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |
Unrecognized compensation cost | $ 2,726,924 |  | $ 2,726,924 |  |
Amortization expense | $ 257,756 | $ 0 |  | $ 0 |

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