Share-Based Compensation (Schedule Of Performance Vesting Restricted Stock Units Granted) (Details)	3 Months Ended
Mar. 31, 2018 shares
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Grant year	2016
Three-year performance period ending December 31,	2018
Vesting shares, target	83,250
Vesting shares, maximum	156,094

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration