Mortgages and Notes Payable - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017
Debt Instrument [Line Items]
Debt satisfaction gains (charges), net	$ 6,196,000	$ (975,000)	$ 25,150,000
Interest paid, capitalized	$ 1,174,000	$ 4,933,000	6,062,000
Mortgages and Notes Payable [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	4.60%	4.60%
Debt satisfaction gains (charges), net	$ 258,000	$ (7,000)	4,128,000
Unsecured Credit Agreement [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	1,105,000,000
Line of credit facility, maximum borrowing capacity with lender approval	$ 2,010,000,000
Minimum [Member] | Mortgages and Notes Payable [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	2.20%
Effective interest percentage		2.20%
Maximum [Member] | Mortgages and Notes Payable [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	7.80%
Effective interest percentage		7.80%
LCIF [Member]
Debt Instrument [Line Items]
Weighted-average interest rate	4.80%	4.70%
Debt satisfaction gains (charges), net	$ 0	$ (7,388,000)	(33,000)
Interest paid, capitalized	596,000	954,000	152,000
Co-borrower debt	$ 157,789,000	$ 146,404,000
LCIF [Member] | Mortgages and Notes Payable [Member]
Debt Instrument [Line Items]
Debt satisfaction gains (charges), net			$ 33,000
LCIF [Member] | Unsecured Credit Agreement [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 1,105,000,000
Line of credit facility, maximum borrowing capacity with lender approval				$ 2,010,000,000
LCIF [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	4.00%	4.00%
LCIF [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt interest rate percentage	6.50%	6.50%