Discontinued Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Statement Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued operations, net of income taxes	$ 0	$ 0	$ (22.0)	$ (21.2)	$ 0	$ (43.2)	$ (80.7)
Basic from discontinued operations (in dollars per share)					$ 0	$ 0.25	$ 0.46
Diluted from discontinued operations (in dollars per share)					$ 0	$ 0.24	$ 0.46
Wexpro [Member]
Income Statement Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues					0	131.2	242.9
Income before income taxes					0	67.4	126.9
Income taxes					0	(24.2)	(46.2)
Discontinued operations, net of income taxes					$ 0	$ 43.2	$ 80.7
Basic from discontinued operations (in dollars per share)					$ 0	$ 0.25	$ 0.46
Diluted from discontinued operations (in dollars per share)					$ 0	$ 0.24	$ 0.46