Debt (Schedule Of Average Commercial Paper Balances Outstanding And Weighted Average Interest Rates) (Details) - Commercial Paper [Member] - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Short-term Debt [Line Items]
Average Balance	$ 56.4	$ 42.3
Weighted Average Interest Rate	2.26%	1.19%

Weighted average interest rate of short-term debt outstanding calculated at point in time.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_ShortTermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant