Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Dec. 31, 2012	Jun. 30, 2013 t
Environmental and Safety Matters [Abstract]
Number of Lawsuits Filed (in ones)		7
Number of Class Action Lawsuits Filed (in ones)		1
Accrual for Environmental Loss Contingencies	$ 7.8	$ 7.3
Number of years the related expenditures are expected to cover assessment and remediation costs (in years)		9
Accrued Environmental Loss Contingencies, Current	2.2	2.2
Accrued Environmental Loss Contingencies, Noncurrent	5.6	5.1
Number of facilities operated affected by non-attainment requirements (in ones)		2
Current ozone standard (in hours)		8-hour
Site Contingency, Name of Site (in ones)	1
Minimum volume of annual greenhouse gas emissions to be reported (in metric tons)		25,000
Commitments for Construction [Abstract]
Purchase Commitment, Remaining Minimum Amount Committed		$ 112.8