Property And Depreciation (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property And Depreciation [Abstract]
Depreciation	$ 36,700,000	$ 36,100,000	$ 37,300,000
Net book value of assets held for sale	0	100,000
Assets held for sale	4,400,000	0	0
Gain on sale of assets held for sale	3,400,000
Losses on impairment of assets	$ 300,000	$ 300,000	$ 300,000