Contingencies (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Commitments and Contingencies Disclosure [Abstract]
Accrual for environmental investigation and remediation activities	$ 7,200,000	$ 4,700,000	$ 4,800,000
Loss contingency, range of possible loss, minimum	0
Loss contingency, range of possible loss, maximum	4,700,000
Accrual for environmental investigation and remediation activities in the second quarter of 2013	2,300,000
Receivable from a third party	$ 1,600,000