Debt (Schedule Of Average Commercial Paper Balances Outstanding And Weighted Average Interest Rates) (Details) - Commercial Paper [Member] - USD ($) $ in Millions	1 Months Ended
	Dec. 31, 2016	Nov. 30, 2016	Oct. 31, 2016	Sep. 30, 2016	Aug. 31, 2016	Jul. 31, 2016	Jun. 30, 2016	May 31, 2016	Apr. 30, 2016	Mar. 31, 2016	Feb. 29, 2016	Jan. 31, 2016
Short-term Debt [Line Items]
Average Balance	$ 63.7	$ 60.8	$ 63.5	$ 60.0	$ 54.2	$ 47.3	$ 76.0	$ 78.2	$ 55.1	$ 30.5	$ 16.9	$ 16.1
Weighted Average Interest Rate	0.86%	0.65%	0.65%	0.65%	0.63%	0.66%	0.62%	0.60%	0.60%	0.60%	0.60%	0.61%