Schedule of Fair Value and Carrying Value of Financial Instruments (Details) (Fair Value, Inputs, Level 2 [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Borrowings under credit facilities	$ 342,000	$ 0
Term loans	477,500	477,500
Bonds payable	42,500	42,500
Mortgage loans	499,859	501,090
Estimated Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Borrowings under credit facilities	342,376	0
Term loans	477,048	476,996
Bonds payable	42,500	42,500
Mortgage loans	$ 508,470	$ 510,250