Business And Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2015	Aug. 14, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business And Summary Of Significant Accounting Policies [Line Items]
Depreciation expense	$ 18,800,000	$ 26,700,000	$ 63,400,000		$ 79,300,000
Environmental remediation, compliance and management expenses			8,300,000	$ 6,500,000	$ 10,400,000
Accrued liability relating to environmental remediation			5,200,000	5,000,000
Deferred costs	9,900,000		0	9,900,000
Amortized costs	2,100,000	$ 4,300,000	$ 7,000,000
New Accounting Pronouncement, Early Adoption, Effect [Member]
Business And Summary Of Significant Accounting Policies [Line Items]
Reclassification of deferred tax assets	10,700,000			10,700,000
Reclassification of deferred tax liabilities	$ 23,300,000			$ 23,300,000