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Retirement Plans (Narrative) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) plan	Mar. 31, 2018 USD ($)
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	$ 200,000
UK Plan | United Kingdom Subsidiary [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	(477,000)	$ (800,000)
Contributions to defined benefit pension plans	1,000,000.0
Anticipated additional contribution	$ 3,600,000

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