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Retirement Benefits - Narrative (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2021 USD ($) employee | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Defined Contribution Plan Disclosure [Line Items] |  |  |
Employer matching contributions | $ | $ 3,766 | $ 3,250 | $ 2,842
Number of employees | 2,900 |  |
Entity number of employees, field personnel | 2,200 |  |
Union Members |  |  |
Defined Contribution Plan Disclosure [Line Items] |  |  |
Number of employees | 400 |  |
Number of employees, percent | 14.00% |  |

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- Details
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