Inventories And Deferred Preservation Costs (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Inventory [Line Items]
Consignment inventory	$ 10.7	$ 9.3
Domestic [Member]
Inventory [Line Items]
Consignment inventory percentage	56.00%	58.00%
Foreign [Member]
Inventory [Line Items]
Consignment inventory percentage	44.00%	42.00%

Gross amount of inventory owned by the entity but in the hands of a customer, typically a reseller.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 605
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 13.A.2.Q2 Response)
-URI http://asc.fasb.org/extlink&oid=65893310&loc=d3e214044-122780

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.6(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_OtherInventoryMaterialsSuppliesAndMerchandiseUnderConsignment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant