Share-Based Compensation (Schedule Of Performance Vesting Restricted Stock Units Granted) (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2011
Share-based Compensation, Allocation and Classification in Financial Statements [Abstract]
Three-year performance period ending December 31,	2015	2014	2013
Vesting shares, target	84,500	89,000	80,000
Vesting shares, maximum	190,125	200,250	120,000

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