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		1 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2011 IEA [Member]
Net proceeds			$ 5
Operating revenues	54.6	68.9
Operating expenses	61.9	67.9
Gain on sale of IEA		(2.5)
Interest expense and other		0.1
Income (loss) before income taxes	(7.3)	3.4
Income tax expense (benefit)	(2.9)	1.9
Income (loss) from discontinued operations, net of tax	$ (4.4)	$ 1.5