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Retirement Plans (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018 USD ($) plan	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) plan	Sep. 30, 2017 USD ($)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	$ 100,000	$ 100,000	$ 200,000	$ 200,000
Number of plans | plan	3		3
Contributions to defined benefit pension plans			$ 100,000
Foreign Plan [Member] | United Kingdom Subsidiary [Member]
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	$ (747,000)	$ (488,000)	(2,327,000)	$ (1,428,000)
Contributions to defined benefit pension plans			3,200,000
Anticipated additional contribution	$ 1,400,000		$ 1,400,000

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