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Employee Benefits - Employee Benefits (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |
Defined contribution plan wage base | $ 280,000 | $ 275,000 | $ 270,000
Requisite service period (in years) | 3 years |  |
Expenses under defined contribution plan | $ 1,900,000 | 1,800,000 | $ 1,500,000
Base Percentage |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contribution percentage to retirement plan | 13.20% |  |
Excess Percentage for amounts above Social Security taxable wage base |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contribution percentage to retirement plan | 5.70% |  |
Nonqualified Plan |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer contribution percentage to retirement plan | 18.90% |  |
Maximum gross annual base salary under plan | $ 500,000 |  |
Expenses for NQDC plan | 100,000 | $ 100,000 |
Nonqualified Plan | Chief Executive Officer |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Maximum gross annual base salary under plan | $ 700,000 |  |

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