Schedule II Valuation And Qualyfying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Trade Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance	$ 9,159	$ 6,886	$ 5,256
Valuation Allowances and Reserves, Additions/Charged to Cost and Expense	4,826	6,347	4,800
Valuation Allowances and Reserves, Recoveries/Write offs	(4,006)	(4,074)	(3,170)
Valuation Allowances and Reserves, Ending Balance	9,979	9,159	6,886
Allowance for Notes Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Beginning Balance	10,026	9,530	9,565
Valuation Allowances and Reserves, Additions/Charged to Cost and Expense	982	678	33
Valuation Allowances and Reserves, Recoveries/Write offs	(1,780)	(182)	(68)
Valuation Allowances and Reserves, Ending Balance	$ 9,228	$ 10,026	$ 9,530