Commitments and Contingencies (Details) (USD $)	3 Months Ended	1 Months Ended	0 Months Ended
	Mar. 31, 2013	Jan. 26, 2011 Limited Number Of Remedial Alternatives [Member]	Jul. 05, 2011 Off-Site [Member]
Site Contingency [Line Items]
Estimated cost, minimum		$ 7,900,000
Estimated cost, maximum		10,500,000
Estimated cost			9,500,000
Payments	1,750,000
Additional increase during period	800,000
Accrual amount	5,000,000
Site Contingency, Loss Exposure in Excess of Accrual, Best Estimate	$ 3,400,000