Discontinued Operations And Assets And Liabilities Held For Sale (Components Of Discontinued Operations In Condensed Consolidated Statements Of Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	$ 94.5	$ 150.7	$ 243.0	$ 326.6
Operating expenses	91.7	175.0	246.6	346.0
Interest expense and other	0.2	(0.2)	0.4	(0.1)
Income (loss) before income taxes	2.6	(24.1)	(4.0)	(19.3)
Income tax expense (benefit)	0.9	(9.2)	(1.7)	(6.7)
Income (loss) from discontinued operations, net of tax	$ 1.7	$ (14.9)	$ (2.3)	$ (12.6)