Commitments and Contingencies (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2011
Environmental Litigation Number 1 [Member]
Site Contingency [Line Items]
Site Contingency, Loss Exposure, Low Estimate	$ 500,000
Site Contingency, Loss Exposure, High Estimate	11,000,000
Accrual for Environmental Loss Contingencies	1,200,000
Estimated Proportional Share Of Cleanup Liability	50.00%
Environmental Litigation Number 2 [Member]
Site Contingency [Line Items]
Site Contingency, Loss Exposure, Low Estimate	340,000
Site Contingency, Loss Exposure, High Estimate	6,400,000
Accrual for Environmental Loss Contingencies	6,400,000
Environmental Litigation Number 3 [Member]
Site Contingency [Line Items]
Site Contingency, Loss Exposure Not Accrued, Best Estimate	8,000,000
Portland Harbor Site [Member]
Site Contingency [Line Items]
Estimated investigative costs (in excess of)	$ 70,000,000