Defined Benefit Pension Plans (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost, non-service cost	$ (257,000)	$ 835,000
U.S.
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	3,000,000	0
U.K. Plan
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer	$ 156,000	$ 193,000