Mortgage and Other Indebtedness, Net (Schedule of Unsecured Lines of Credit) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Total Outstanding	$ 1,065,450,000	$ 888,770,000
Wells Fargo Bank
Debt Instrument [Line Items]
Letter of credit, outstanding	$ 150,000
Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit, extension fee	0.15%
Wells Fargo - Facility A
Debt Instrument [Line Items]
Total Capacity	$ 500,000,000
Total Outstanding	0
Unsecured Line of Credit, First Tennessee
Debt Instrument [Line Items]
Total Capacity	100,000,000
Total Outstanding	$ 36,034,000
Unsecured Line of Credit, First Tennessee | Wells Fargo Bank
Debt Instrument [Line Items]
Line of credit, extension fee	0.20%
Wells Fargo - Facility B
Debt Instrument [Line Items]
Total Capacity	$ 500,000,000
Total Outstanding	43,936,000
Unsecured lines of credit
Debt Instrument [Line Items]
Total Capacity	1,100,000,000
Total Outstanding	79,970,000
Wells Fargo Bank | Letter of Credit
Debt Instrument [Line Items]
Total Capacity	30,000,000
First Tennessee Bank
Debt Instrument [Line Items]
Total Capacity	$ 20,000,000