Commitments and Contingencies - Congress Development Landfill Matters (Details Textual 4) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011	Dec. 23, 2009 Plaintiffs
Commitments and Contingencies [Line Items]
Remediation liability	$ 557.3	$ 563.7	$ 530.0	$ 543.7
Additional plaintiffs approximately filed suit in the Circuit Court (in plaintiffs)					2,950
Minimum damages sought	50
Punitive damages minimum	50
Congress Landfill [Member]
Commitments and Contingencies [Line Items]
Remediation liability	83.7
Expected remediation liability to be paid during the next 12 months	8.2
Range of loss for remediation costs (minimum)	53
Range of loss for remediation costs (maximum)	$ 154

Total costs accrued as of the balance sheet date for environmental loss contingencies.

The estimated maximum amount of possible loss from the contingency.

The estimated minimum amount of possible loss from the contingency.