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Stock-Based Compensation Plans (Narrative) (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 USD ($) plan shares | Jun. 30, 2020 USD ($) | Jun. 30, 2021 USD ($) plan shares | Jun. 30, 2020 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Compensation expense for share-based payments | $ 6,727,513 | $ 9,641,353 | $ 12,622,158 | $ 15,960,362
Omnibus Incentive Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Total grants in period (in shares) | shares |  |  | 5,735,302 |
Shares issued under the Omnibus plan | shares |  |  | 14,332,742 |
Number of shares authorized | shares | 45,000,000 |  | 45,000,000 |
Employee Stock Option Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Unrecognized compensation cost | $ 8,999,790 |  | $ 8,999,790 |
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 |
Restricted Stock Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Unrecognized compensation cost | 50,874,177 |  | $ 50,874,177 |
Restricted period, maximum |  |  | 10 years |
Amortization expense | $ 4,459,401 | 7,580,492 | $ 8,762,376 | 11,905,749
Restricted Stock Plan | Employee Severance |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Amortization expense |  | 4,148,477 |  |
Employee Stock Purchase Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Shares approved | 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 | 1,423,819 |  | 1,423,819 |
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 | $ 9,456,469 |  | $ 9,456,469 |
Amortization expense | $ 701,524 | $ 563,783 | $ 805,754 | $ 957,560

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