Property And Depreciation (Schedule Of Property And Depreciation) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 36,700,000	$ 36,100,000	$ 37,300,000
Net book value of assets held for sale	0	100,000
Gain on sale of assets held for sale	3,400,000
Losses on impairment of assets	$ 300,000	$ 300,000	$ 300,000
Building
Property, Plant and Equipment [Line Items]
Estimated useful asset life	42 years
Furniture, Fixtures & Equipment and Software [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful asset life	3 years
Furniture, Fixtures & Equipment and Software [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful asset life	14 years