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Equity-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2018 | Dec. 31, 2019 | May 04, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Market price of common stock, per share |  | $ 50.44 |
Unrecognized compensation cost |  | $ 10.9 |
Weighted average cost recognition period, in years |  | 2 years 2 months 12 days |
Accrued equity based compensation | $ 38.4 | $ 28.0 |
Performance Stock Units |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Performance stock unit compensation expense |  | $ 8.9 |
Maximum |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Typical vesting period, in years |  | 4 years |
Performance stock units |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Shares awarded (in shares) |  | 194,658 |
Forfeited in period (in shares) |  | 8,190 |
Performance stock units outstanding (in shares) | 235,485 | 329,257 |
Percent of targeted performance stock units earned |  | 200.00% |
Units vested (in shares) |  | 256,000 |
Number of days trailing for closing price | 90 days |  |
2018 Plan | Common Stock |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of shares authorized |  |  | 1,000,000
2015 Equity Incentive Plan |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of shares available for issuance under the Plan |  | 699,000 |
2015 Equity Incentive Plan |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of shares available for issuance under the Plan |  | 157,000 |
Non-Employee Directors Plan |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Number of shares available for issuance under the Plan |  | 45,000 |
Accrued Expenses, Current |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Accrued equity based compensation |  | $ 14.8 |
Non Current Liabilities |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Accrued equity based compensation | $ 23.6 | $ 13.2 |

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