Retirement Plans (Narrative) (Details)	3 Months Ended
Mar. 31, 2020 USD ($) plan	Mar. 31, 2019 USD ($)
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	$ 100,000	$ 100,000
Number of plans \| plan	3
Contributions to defined benefit pension plans	$ 0
UK Plan \| United Kingdom Subsidiary [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	(806,000)	$ (477,000)
Contributions to defined benefit pension plans	1,000,000.0
Anticipated additional contribution	$ 3,500,000

Defined Benefit Plan, Number Of Plans

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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+ References

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Amount of contributions expected to be received by defined benefit plan from employer in fiscal year. Excludes contributions paid by employer in current fiscal year.

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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