Noncash Investing and Financing Activities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Other Significant Noncash Transactions [Line Items]
Accrued dividends and distributions payable	$ 54,569	$ 54,491
Additions to real estate assets accrued but not yet paid	5,326	3,965
River Ridge Mall
Other Significant Noncash Transactions [Line Items]
Increase in investment in unconsolidated affiliate	14,030	0
Decrease in accounts payable and accrued liabilities	(5)	0
Transfer of Real Estate Assets in Settlement of Mortgage Debt Obligations | River Ridge Mall
Other Significant Noncash Transactions [Line Items]
Decrease in real estate assets	$ (14,025)	$ 0