Liabilities for Dispositions and Discontinued Operations (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Accrual for Environmental Loss Contingencies [Roll Forward]
Liabilities for dispositions and discontinued operations, beginning of period	$ 93,160,000	$ 98,591,000
Expenditures charged to liabilities	(4,916,000)	(8,632,000)
Increase to liabilities	309,000	3,201,000
Liabilities for dispositions and discontinued operations, end of period	88,553,000	93,160,000
Less: Current portion	(11,625,000)	(11,500,000)
Non-current portion	76,928,000	81,660,000
Environmental Loss Contingencies Term Liabilities to Cover Costs	20 years
Environmental Exit Costs, Reasonably Possible Additional Losses, High Estimate	$ 40,000,000