Write-downs, reserves and recoveries, net (Details) (USD $)	3 Months Ended			6 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Write Downs Reserves And Recoveries Net Abstract
Impairment of assets	$ 0		$ 500,000	$ 100,000	$ 500,000
Loss on disposal of assets	5,900,000		1,200,000	6,100,000	1,600,000
Legal settlement recoveries	0		0	400,000	(6,500,000)
Write-downs, reserves and recoveries, net			1,657,000		(4,378,000)
Proceeds from Legal Settlements		6,500,000
Loss on Donation of Land	$ 5,700,000