Financings And Capitalization (Issuance Of Common Stock) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			24 Months Ended
	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2013
Financings And Capitalization [Abstract]
Number of Shares Issued	735,873	650,235	762,925	2,149,033
Average Price Per Share	$ 27.18	$ 23.07	$ 19.66	$ 23.27
Proceeds	$ 20	$ 15	$ 15	$ 50