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Retirement Plans (Narrative) (Details) | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 USD ($) plan | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) plan | Sep. 30, 2019 USD ($)
UNITED STATES |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Number of plans | plan | 3 |  | 3 |
Contributions to defined benefit pension plans |  |  | $ 100,000 |
Net periodic pension cost (income) | $ 100,000 | $ 100,000 | 200,000 | $ 200,000
UK Plan | United Kingdom Subsidiary [Member] |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |
Contributions to defined benefit pension plans |  |  | 3,400,000 |
Anticipated additional contribution | 1,300,000 |  | 1,300,000 |
Net periodic pension cost (income) | $ (815,000) | $ (450,000) | $ (2,406,000) | $ (1,397,000)

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