Retirement Plans (Components Of Net Periodic Pension Benefit Cost) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Net periodic pension cost (income)	$ 100,000	$ 100,000
UK Plan | United Kingdom Subsidiary [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	1,596,000	2,039,000
Expected return on plan assets	(2,997,000)	(3,116,000)
Amortization of unrecognized loss	595,000	600,000
Net periodic pension cost (income)	$ (806,000)	$ (477,000)