Commitments and Contingencies (Details) (USD $)				3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		12 Months Ended	0 Months Ended	3 Months Ended		3 Months Ended			3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Former Owner / Operator [Member]	Mar. 31, 2013 Superfund [Member] potentially_responsible_party	Dec. 31, 2009 Superfund [Member] number_of_payments	Mar. 31, 2013 Superfund [Member] Remediation Projection, Early Action Items [Member]	Dec. 31, 2009 Superfund [Member] Remediation Projection, Early Action Items [Member]	Mar. 11, 2009 Superfund [Member] Remediation Projection, Early Action Items [Member]	Dec. 31, 2009 Superfund [Member] Previously Expended, Adjustment [Member]	Dec. 31, 2009 Sold Parcel [Member]	Mar. 31, 2013 Sold Parcel [Member]	Jan. 31, 2010 Sold Parcel [Member]	Mar. 31, 2013 Costs [Member] Former Owner / Operator [Member]	Mar. 31, 2013 Costs [Member] Second Joint Venture Partner of Former Owner / Operator [Member]	Mar. 31, 2013 Costs [Member] First Joint Venture Partner of Former Owner / Operator [Member]	Mar. 31, 2013 Costs [Member] HHEM [Member]	Mar. 31, 2013 Costs [Member] Hhem and HandH [Member]
Environmetal Remediation Obligations [Line Items]
Accrued environmental liabilities	$ 6,222,000	$ 6,346,000
Environmental remediation expense										29,200,000			2,600,000			900,000
Remediation cost, expected cost											100,000
Third-party environmental recoveries, amount										2,000,000		1,000,000
Ownership responsibility for site investigation and remediation costs, percentage allocation (as a percent)			75.00%											37.50%	37.50%		25.00%
Environmental loss contingencies, payments							0		0								1,000,000
Environmental loss contingencies, number of potentially responsible parties (in potentially responsible parties)				13
Environmental loss contingencies, number of required payments (in number of payments)					2
Loss Contingency, Financial Guarantee								$ 2,600,000
Loss Contingency, Entity Share of Liability (as a percent)						14.69%