Mortgage and Other Indebtedness - Consolidated Indebtedness by Type of Interest Rate (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Amount	$ 1,732,344	$ 1,724,449
Percentage of Total	100.00%
Weighted Average Interest Rate	4.03%
Weighted Average Maturity (Years)	6 years 7 months 6 days
Fixed Rate Debt Considering Hedges
Debt Instrument [Line Items]
Amount	$ 1,648,718
Percentage of Total	95.00%
Weighted Average Interest Rate	4.13%
Weighted Average Maturity (Years)	6 years 8 months 12 days
Variable Rate Debt Considering Hedges
Debt Instrument [Line Items]
Amount	$ 83,616
Percentage of Total	5.00%
Weighted Average Interest Rate	2.03%
Weighted Average Maturity (Years)	5 years 4 months 24 days
Net Premiums On Acquired Debt
Debt Instrument [Line Items]
Amount	$ 10
Variable Rate Debt | Floating Rate Debt Hedged
Debt Instrument [Line Items]
Amount	$ 474,700
Weighted Average Maturity (Years)	2 years 10 months 24 days