Contingencies and Off-Balance Sheet Commitments (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Environmental indemnification obligations
Aggregate amounts accrued for environmental liabilities	$ 2,600,000	$ 2,600,000
Legal Proceedings
Public liability and property damage	321,003,000	332,232,000
Pending Litigation [Member] \| Sobel Case [Member]
Legal Proceedings
Estimate of possible loss	$ 40,000,000

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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