Receivables (Details) (USD $)									3 Months Ended		6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 Trade Accounts Receivable [Member]	Dec. 31, 2010 Trade Accounts Receivable [Member]	Jun. 30, 2011 Notes Receivable [Member]	Dec. 31, 2010 Notes Receivable [Member]	Jun. 30, 2011 Other Receivables [Member]	Dec. 31, 2010 Other Receivables [Member]	Jun. 30, 2011 Allowance for Doubtful Accounts, Current [Member]	Jun. 30, 2010 Allowance for Doubtful Accounts, Current [Member]	Jun. 30, 2011 Allowance for Doubtful Accounts, Current [Member]	Jun. 30, 2010 Allowance for Doubtful Accounts, Current [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables			$ 151,671,000	$ 126,671,000	$ 44,000	$ 139,000	$ 660,000	$ 748,000
Allowance for doubtful accounts receivable	(309,000)	(260,000)
Net receivables	152,066,000	127,298,000
Valuation and Qualifying Accounts Disclosure [Line Items]
Bad debt expense										100,000	0
Collections on previous bad debts									$ 0			$ 200,000