Commitments and Contingencies - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017 USD ($) ft² ShoppingCenter Store	Dec. 31, 2017 USD ($) ft² ShoppingCenter Store Position Officer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2019 Property	Dec. 31, 2018 Property	Feb. 15, 2018	Jan. 31, 2018 ShoppingCenter
Contingencies And Commitments [Line Items]
Estimated insurance recoveries receivable	$ 58,583	$ 58,583	$ 0
Insurance proceeds related to business interruption insurance claims		8,500	0	$ 0
Mortgage indebtedness	$ 641,082	$ 641,082	$ 982,509
Mortgage, Weighted Average Interest Rate	4.20%	4.20%	4.90%
Stock-based compensation expense		$ 5,500	$ 900	$ 500
Agreements entered into with general contractors for the construction or redevelopment of shopping centers	$ 19,300	19,300
Outstanding letters of credit	17,300	17,300
Affiliate debt guaranty	$ 4,000	$ 4,000
Mortgage debt maturity, year and month		2020-10
Long-term ground leases expiration period		various dates through 2070
Minimum [Member]
Contingencies And Commitments [Line Items]
Period space in shopping centers leased		1 month
Maximum [Member]
Contingencies And Commitments [Line Items]
Period space in shopping centers leased		30 years
Employee Severance [Member]
Contingencies And Commitments [Line Items]
Stock-based compensation expense		$ 4,500
Employee Severance [Member] | Elimination [Member]
Contingencies And Commitments [Line Items]
Total number of positions eliminated including officer level | Position		65
Number of positions eliminated | Officer		9
General and Administrative [Member] | Employee Severance [Member]
Contingencies And Commitments [Line Items]
Separation charge		$ 17,900
General and Administrative [Member] | Employee Severance [Member] | Executive Management Transition [Member]
Contingencies And Commitments [Line Items]
Separation charge		9,400
General and Administrative [Member] | Employee Severance [Member] | Elimination [Member]
Contingencies And Commitments [Line Items]
Separation charge		$ 7,200
Puerto Rico [Member]
Contingencies And Commitments [Line Items]
Number of properties owned | ShoppingCenter	12	12
Gross leasable area of properties owned | ft²	4,400,000	4,400,000
Gross leasable area of anchor spaces | ft²	25,000	25,000
Insurance Policy Limit		$ 330,000
Hurricane casualty and impairment loss		$ 6,000
Number of properties encumbered by mortgage/notes | ShoppingCenter	6	6
Mortgage indebtedness	$ 263,400	$ 263,400
Mortgage, Weighted Average Interest Rate	4.90%	4.90%
Puerto Rico [Member] | Scenario Forecast [Member]
Contingencies And Commitments [Line Items]
Number of properties anticipated to be repaired | Property						8
Additional properties to be substantially complete | Property					3
Puerto Rico [Member] | Loss from Catastrophes
Contingencies And Commitments [Line Items]
Number of assets sustained varying degrees of damage | ShoppingCenter	11	11
Percentage of tenants opened in anchor space properties post hurricanes	79.00%	79.00%
Number of stores opened in anchor space properties post hurricanes | Store	26	26
Estimated net book value of the property damage written off	$ 71,000	$ 71,000
Estimated insurance recoveries receivable	58,600	58,600
Property damage insurance deductible		5,100
Proceeds from insurance claims		$ 10,000
Business interruption insurance coverage period after restoration		365 days
Rental revenues lost and not recognized		$ 11,800
Business interruption insurance claim deductible		$ 900
Puerto Rico [Member] | Loss from Catastrophes | Business Interruption Income [Member]
Contingencies And Commitments [Line Items]
Insurance proceeds related to business interruption insurance claims	$ 8,500
Puerto Rico [Member] | Loss from Catastrophes | Subsequent Event [Member]
Contingencies And Commitments [Line Items]
Number of properties owned, having full utility power post catastrophe | ShoppingCenter								12
Percentage of leased gross leasable area opened in anchor space properties post hurricanes							85.00%
Puerto Rico [Member] | Loss from Catastrophes | Plaza Palma Real [Member]
Contingencies And Commitments [Line Items]
Number of properties owned that was severely damaged | ShoppingCenter	1	1
Gross leasable area of properties owned that was severely damaged | ft²	400,000	400,000
Puerto Rico [Member] | Loss from Catastrophes | Plaza Palma Real [Member] | Subsequent Event [Member]
Contingencies And Commitments [Line Items]
Percentage of leased gross leasable area opened in anchor space properties post hurricanes							76.00%
Puerto Rico [Member] | Loss from Catastrophes | Walmart [Member]
Contingencies And Commitments [Line Items]
Number of stores opened in anchor space properties post hurricanes | Store	6	6
Number of store in anchor space properties | Store	7	7
Puerto Rico [Member] | Loss from Catastrophes | Sam's Club [Member]
Contingencies And Commitments [Line Items]
Number of stores opened in anchor space properties post hurricanes | Store	1	1
Puerto Rico [Member] | Loss from Catastrophes | Home Depot [Member]
Contingencies And Commitments [Line Items]
Number of stores opened in anchor space properties post hurricanes | Store	2	2
Puerto Rico [Member] | Loss from Catastrophes | Sears/Kmart [Member]
Contingencies And Commitments [Line Items]
Number of stores opened in anchor space properties post hurricanes | Store	3	3
Puerto Rico [Member] | Loss from Catastrophes | Other Grocery Stores [Member]
Contingencies And Commitments [Line Items]
Number of stores opened in anchor space properties post hurricanes | Store	5	5