Summary Of Significant Accounting Policies (Casualty Loss) (Narrative) (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)
Property, Plant and Equipment [Line Items]
Loss from catastrophes	$ 7,789
Book Value of Assets Damaged [Member]
Property, Plant and Equipment [Line Items]
Loss from catastrophes	3,300
Repairs And Maintenance [Member]
Property, Plant and Equipment [Line Items]
Loss from catastrophes	$ 4,500

The charge against earnings in the period for the uninsured portion of a loss from a fire, explosion, or natural disaster (hurricane, earthquake).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Name:	us-gaap_LossFromCatastrophes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration