Debt And Credit Agreements (Summary Of Total Debt Due And Outstanding) (Details)	12 Months Ended
Dec. 31, 2020
Secured Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, covenant terms, maximum debt to EBITDA ratio	4.00

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration