Schedule II (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	$ 6,672	$ 5,951	$ 3,822
Additions to allowance for doubtful accounts	2,522	4,009	5,639
Deductions to allowance for doubtful accounts	(4,291)	(3,288)	(3,510)
Allowance for doubtful accounts, ending balance	4,903	6,672	5,951
Allowance for Doubtful Accounts - Straight Line Rent [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	2,209	2,443	2,082
Additions to allowance for doubtful accounts	710	635	2,484
Deductions to allowance for doubtful accounts	(1,625)	(869)	(2,123)
Allowance for doubtful accounts, ending balance	1,294	2,209	2,443
Allowance for Doubtful Accounts - Accounts Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	3,595	2,810	1,281
Additions to allowance for doubtful accounts	1,616	2,961	2,900
Deductions to allowance for doubtful accounts	(1,663)	(2,176)	(1,371)
Allowance for doubtful accounts, ending balance	3,548	3,595	2,810
Allowance for Doubtful Accounts - Notes Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Allowance for doubtful accounts, beginning balance	868	698	459
Additions to allowance for doubtful accounts	196	413	255
Deductions to allowance for doubtful accounts	(1,003)	(243)	(16)
Allowance for doubtful accounts, ending balance	$ 61	$ 868	$ 698