Basis Of Presentation and Recent Accounting Pronouncements (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Retained earnings		$ (196,000,000)	$ (203,400,000)
Accounting Standards Update 2018-02 [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Retained earnings		0
Accounting Standards Update 2017-07 [Member] | Retained Earnings [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component	$ 0
Accounting Standards Update 2014-09 [Member] | Accounts Receivable [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		28,600,000
Accounting Standards Update 2014-09 [Member] | Accrued Liabilities [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		(1,600,000)
Accounting Standards Update 2014-09 [Member] | Deferred Income Tax Liability [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		(1,200,000)
Accounting Standards Update 2014-09 [Member] | Inventories [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		(23,000,000)
Retained Earnings [Member] | Accounting Standards Update 2014-09 [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ (2,800,000)
Cost of Sales [Member] | Accounting Standards Update 2017-07 [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component	(500,000)
Selling, General and Administrative Expenses [Member] | Accounting Standards Update 2017-07 [Member]
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Net Periodic Defined Benefits Expense Reversal Of Expense Excluding Service Cost Component	$ (300,000)