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Stock Compensation Plans (Narrative) (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2019 | Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock options outstanding (in shares) | 0 | 0
RSUs | Ratably |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Vesting period | 3 years |
RSUs | Cliff | Minimum |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Vesting period | 3 years |
RSUs | Cliff | Maximum |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Vesting period | 5 years |
Performance-Based RSUs |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Total unrecognized compensation cost | $ 16.6 |
Weighted average period to recognize unrecognized compensation cost | 1 year 11 months 23 days |
Performance-Based RSUs | Minimum |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Potential for awards to vest (as a percent) | 0.00% |
Performance-Based RSUs | Maximum |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Potential for awards to vest (as a percent) | 200.00% |
Performance-Based RSUs | Cliff |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Vesting period | 3 years |
Time-Based RSUs |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Total unrecognized compensation cost | $ 27.6 |
Weighted average period to recognize unrecognized compensation cost | 1 year 10 months 20 days |

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