Business And Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Depreciation expense	$ 49,700,000	$ 53,500,000	$ 50,400,000
Deferred costs	20,200,000	24,300,000
Amortized costs	4,100,000	3,500,000	300,000
Environmental remediation, compliance and management expenses	11,600,000	12,400,000	8,000,000.0
Accrued liability relating to environmental remediation	4,900,000	4,200,000
Capitalized maintenance cost		800,000	9,800,000
Amortization of deferred maintenance cost	5,100,000	3,100,000	$ 3,300,000
Capital expenses included in accounts payable	$ 11,500,000	$ 13,700,000