Noncash Investing and Financing Activities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Other Significant Noncash Transactions [Line Items]
Accrued dividends and distributions payable	$ 54,375	$ 54,313
Additions to real estate assets accrued but not yet paid	12,204	16,495
Capital contribution of note receivable to joint venture	0	5,280
Capital contribution from noncontrolling interest to joint venture	0	155
Write-off of notes receivable	0	1,846
Mortgage debt assumed by buyer of real estate assets	0	38,237
Decrease in noncontrolling interest and joint venture interest	2,232
Partnership Interest
Other Significant Noncash Transactions [Line Items]
Decrease in real estate assets	0	(14,025)
Increase in investment in unconsolidated affiliate	0	14,030
Decrease in accounts payable and accrued liabilities	0	(5)
Outlet Shoppes at Atlanta - Ridgewalk
Other Significant Noncash Transactions [Line Items]
Decrease in real estate assets	(149,722)	0
Decrease in mortgage and other indebtedness	189,642	0
Decrease in operating assets and liabilities	(122)	0
Corporate Joint Venture
Other Significant Noncash Transactions [Line Items]
Decrease in real estate assets	(9,131)	0
Decrease in mortgage and other indebtedness	2,466	0
Decrease in operating assets and liabilities	1,286	0
Decrease in noncontrolling interest and joint venture interest	$ 2,232	$ 0