Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Commitments and Contingencies [Abstract]
Accrued liability related to assessment and/or remediation costs	$ 10.6	$ 11.2
Number of years the related expenditures are expected to cover	10
Assessment and remediation costs recorded in other current liabilities	3.6	3.6
Assessment and remediation cost recorded in other liabilities and deferred credits	7.0	7.6
Number of facilities operated by subsidiaries in areas affected by non-attainment requirements	2
Current ozone standard	8
Maximum numbers of facilities that may require additional compliance	12
Minimum volume of annual greenhouse gas emissions to be reported	25,000
Future capital commitment
2011	46.0
2012	0
2013	0
2014	0
2015	0
Thereafter	0
Total	$ 46.0