Combined Guarantor Subsidiaries - Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Rental revenues	$ 185,393	$ 207,568	$ 376,373	$ 420,297
Revenues from contracts with customers (ASC 606):	5,865	5,739	11,405	12,098
Total revenues	193,377	214,598	391,407	434,798
Malls
Disaggregation of Revenue [Line Items]
Total revenues	170,976	195,942	354,840	396,657
All Other
Disaggregation of Revenue [Line Items]
Total revenues	22,401	18,656	36,567	38,141
Operating expense reimbursements
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	2,061	2,168	4,204	4,511
Operating expense reimbursements | Malls
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	1,217	927	2,093	2,221
Operating expense reimbursements | All Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	1	1	(1)	2
Marketing revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	1,218	928	2,092	2,223
Marketing revenues | Malls
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	1,892	2,083	4,084	4,273
Marketing revenues | All Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	169	85	120	238
Other revenues
Disaggregation of Revenue [Line Items]
Other revenues	2,119	1,291	3,629	2,403
Guarantor Subsidiaries
Disaggregation of Revenue [Line Items]
Rental revenues	67,316	76,976	138,588	155,682
Revenues from contracts with customers (ASC 606):	1,242	1,375	2,830	3,051
Total revenues	68,868	78,591	141,859	159,029
Guarantor Subsidiaries | Malls
Disaggregation of Revenue [Line Items]
Total revenues	66,403	75,906	136,803	153,567
Guarantor Subsidiaries | All Other
Disaggregation of Revenue [Line Items]
Total revenues	2,465	2,685	5,056	5,462
Guarantor Subsidiaries | Operating expense reimbursements
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	693	966	1,844	2,134
Guarantor Subsidiaries | Operating expense reimbursements | Malls
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	688	949	1,839	2,117
Guarantor Subsidiaries | Operating expense reimbursements | All Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	5	17	5	17
Guarantor Subsidiaries | Marketing revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	549	409	986	917
Guarantor Subsidiaries | Marketing revenues | Malls
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	549	409	986	917
Guarantor Subsidiaries | Other revenues
Disaggregation of Revenue [Line Items]
Other revenues	$ 310	$ 240	$ 441	$ 296