Schedule II (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of the Year	$ 7,761	$ 7,014	$ 7,453
Additions	4,983	3,320	2,812
Deductions	(5,344)	(2,573)	(3,251)
Balance at End of the Year	7,400	7,761	7,014
Allowance for Trade Receivable, Straight Line Rent [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of the Year	823	798	1,311
Additions	1,097	815	350
Deductions	(1,010)	(790)	(863)
Balance at End of the Year	910	823	798
Allowance for Trade Receivables [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of the Year	6,938	6,216	6,142
Additions	3,886	2,505	2,462
Deductions	(4,334)	(1,783)	(2,388)
Balance at End of the Year	$ 6,490	$ 6,938	$ 6,216