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	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Operating revenues	$ 289.2	$ 445.0	$ 160.3
Operating expenses	297.0	476.9	166.8
Interest expense and other	0.7	0	1.0
Loss before income taxes	(8.5)	(31.9)	(7.5)
Income tax benefit	(3.4)	(12.4)	(3.6)
Loss from discontinued operations, net of tax	(5.1)	(19.5)	(3.9)
IEA [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds		5
RMT [Member] | Environmental [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds		$ 12