Mortgages and Notes Payable - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 30, 2015
Debt Instrument [Line Items]
Mortgages and notes payable	$ 882,952,000	$ 945,216,000
Weighted-average interest rate	4.90%	5.20%
Gains (charges) on debt satisfaction from continuing operations	$ 4,122,000	$ (7,016,000)	$ (11,811,000)
Interest paid, capitalized	$ 6,062,000	$ 3,441,000	$ 2,397,000
Unsecured Credit Agreement [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 905,000,000
Line of credit facility, maximum borrowing capacity with lender approval				$ 1,810,000,000
Minimum [Member]
Debt Instrument [Line Items]
Effective interest rate	2.20%	2.20%
Maximum [Member]
Debt Instrument [Line Items]
Effective interest rate	7.80%	8.50%