Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended				12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 ACP [Member]	Dec. 31, 2007 ACP [Member]	Mar. 31, 2013 SB Decking [Member]	Mar. 31, 2013 VAT, Total [Member]	Dec. 31, 2010 VAT, Total [Member]	Dec. 31, 2010 VAT Settlement One [Member]	Dec. 31, 2010 VAT Settlement Two [Member]
Loss Contingencies [Line Items]
Gain (Loss) Related to Litigation Settlement				$ 2,000			$ 4,132	$ 3,901	$ 231
Loss Contingency, Range of Possible Loss, Minimum			600			0
Loss Contingency, Range of Possible Loss, Maximum			1,000			12,500
P-2 Well Operation Range Estimate			another one and one-quarter to two and three-quarter years
P-3 Well Operation Range Estimate			three months
Unrelated Environmental Liability Accruals	245	230
Loss Contingency, Estimate of Possible Loss					$ 3,300
Loss Contingency, Settlement Agreement, Terms					In response, two of the three carriers entered into separate settlement and release agreements with the subsidiary in late 2005 and early 2007 for $15,000 and $20,000, respectively. The proceeds of both settlements are restricted and can only be used to pay claims and costs of defense associated with the subsidiary’s asbestos litigation. During the third quarter of 2007, the subsidiary and the remaining primary insurance carrier entered into a Claim Handling and Funding Agreement, under which the carrier will pay 27% of defense and indemnity costs incurred by or on behalf of the subsidiary in connection with asbestos bodily injury claims for a minimum of five years beginning July 1, 2007. The agreement continues until terminated and can only be terminated by either party by providing the other party with a minimum of two years prior written notice. As of March 31, 2013, no notice of termination has been given under this agreement. At the end of the term of the agreement, the subsidiary may choose to again pursue its claim against this insurer regarding the application of the policy limits.
Percentage of Potential Exposure Represented by One Jurisdiction						82.00%