Revenues - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Rental revenues	$ 180,616	$ 200,311	$ 556,989	$ 620,608
Rental revenues		200,311		620,608
Total revenues	187,251	206,878	578,658	641,676
Malls
Disaggregation of Revenue [Line Items]
Total revenues	171,514	188,440	526,354	585,097
All Other
Disaggregation of Revenue [Line Items]
Total revenues	15,737	18,438	52,304	56,579
Total Revenue
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	5,721	5,906	17,126	18,004
Operating expense reimbursements
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	2,449	2,086	6,653	6,597
Management, development and leasing fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	2,216	2,658	7,325	8,022
Marketing revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	1,056	1,162	3,148	3,385
Marketing revenues | Malls
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	2,374	1,903	6,458	6,176
Marketing revenues | All Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers (ASC 606):	75	183	195	421
Other revenues
Disaggregation of Revenue [Line Items]
Other revenues	$ 914	$ 661	$ 4,543	$ 3,064