Indebtedness - Additional Information (Detail)			3 Months Ended
	Feb. 14, 2018 USD ($) ShoppingCenter Option	Dec. 14, 2017 ShoppingCenter	Mar. 31, 2018 USD ($) ShoppingCenter	Mar. 31, 2017 USD ($)	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Mortgage indebtedness			$ 1,505,235,000						$ 641,082,000
Repayments of senior notes			924,751,000	$ 0
Repayment of outstanding mortgage debt			678,721,000	$ 63,302,000
U.S. [Member]
Debt Instrument [Line Items]
Number of shopping centers the company intended to spinoff | ShoppingCenter		38
Puerto Rico [Member]
Debt Instrument [Line Items]
Number of shopping centers the company intended to spinoff | ShoppingCenter		12
Promissory Notes [Member] | First One-year Extension Option [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt yield ratio	11.00%
Promissory Notes [Member] | First One-year Extension Option [Member] | Maximum [Member]
Debt Instrument [Line Items]
Loan-to-value ratio	50.00%
Promissory Notes [Member] | Second One-year Extension Option [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt yield ratio	12.00%
Promissory Notes [Member] | Second One-year Extension Option [Member] | Maximum [Member]
Debt Instrument [Line Items]
Loan-to-value ratio	45.00%
Mortgages indebtedness [Member]
Debt Instrument [Line Items]
Mortgage indebtedness			$ 1,350,000,000
Number of shopping centers the company intended to spinoff | ShoppingCenter			50
Loan Agreement
Debt Instrument [Line Items]
Debt instrument extension options maturity period	3 years
Minimum percentage distribution of REIT			20.00%
Prepayment premium amount expected to be paid in future	$ 0
Loan Agreement | Debt Yield Less Than or Equal to 12.0% [Member]
Debt Instrument [Line Items]
Debt yield ratio	12.00%
Percentage of property’s net sale proceeds	100.00%
Allocated loan amount percentage	110.00%
Loan Agreement | Debt Yield is Greater Than 12.0% But Less Than or Equal to 15.0% [Member]
Debt Instrument [Line Items]
Percentage of property’s net sale proceeds	90.00%
Allocated loan amount percentage	105.00%
Loan Agreement | Debt Yield Greater Than 15.0% [Member]
Debt Instrument [Line Items]
Percentage of property’s net sale proceeds	80.00%
Allocated loan amount percentage	100.00%
Loan Agreement | Mortgage-backed Securities [Member]
Debt Instrument [Line Items]
Interest rate description			one-month LIBOR plus a spread of 2.91% per annum
Loan Agreement | Mortgage-backed Securities [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Specified spread line of credit facility	2.91%
Loan Agreement | Minimum [Member]
Debt Instrument [Line Items]
Debt yield ratio	15.00%
Loan Agreement | Minimum [Member] | Debt Yield is Greater Than 12.0% But Less Than or Equal to 15.0% [Member]
Debt Instrument [Line Items]
Debt yield ratio	12.00%
Loan Agreement | Maximum [Member] | Debt Yield is Greater Than 12.0% But Less Than or Equal to 15.0% [Member]
Debt Instrument [Line Items]
Debt yield ratio	15.00%
Loan Agreement | Scenario Forecast [Member]
Debt Instrument [Line Items]
Debt yield ratio					19.20%	14.10%	11.90%	10.80%
Loan Agreement | U.S. [Member]
Debt Instrument [Line Items]
Percentage of property’s net sale proceeds	100.00%
Loan Agreement | Puerto Rico [Member]
Debt Instrument [Line Items]
Minimum release price of property's	$ 350,000,000
Loan Agreement | Promissory Notes [Member]
Debt Instrument [Line Items]
Mortgage indebtedness	$ 1,350,000,000
Debt instrument maturity date	Feb. 09, 2021
Debt instrument number of extension options | Option	2
Debt instrument extension options maturity period	1 year
Debt instrument, conditions for extension options	two successive one-year extensions at Borrowers’ option conditioned upon, among other items, (i) an event of default shall not be continuing, (ii) in the case of the first one-year extension option, evidence that the debt yield (as defined and calculated in accordance with the Loan Agreement, but which is the ratio of net operating income of the continental U.S. properties to the outstanding principal amount of the Loan Facility) (the “Debt Yield”) equals or exceeds 11% and the ratio of the outstanding principal amount of the Notes to the value of the continental U.S. properties (based on appraisal values determined at the time of the initial closing) (the “Loan-to-Value Ratio”) is less than or equal to 50%, and (iii) in the case of the second one-year extension option, evidence that the Debt Yield equals or exceeds 12% and the Loan-to-Value Ratio is less than or equal to 45%.
Interest rate description			one-month LIBOR plus a spread of 3.15% per annum
Percentage of increase in debt instrument exercise of first extension option	0.25%
Percentage of increase in debt instrument exercise of second extension option	0.25%
Derivative cap interest rate	3.00%
Debt service coverage ratio	120.00%
Loan Agreement | Promissory Notes [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Specified spread line of credit facility	3.15%
Loan Agreement | Promissory Notes [Member] | Default [Member]
Debt Instrument [Line Items]
Description of event of default			In the event of a default, the contract rate of interest on the Notes will increase to the lesser of (i) the maximum rate allowed by law, or (ii) the greater of (A) 4% above the interest rate otherwise applicable and (B) the Prime Rate (as defined in the Loan Agreement) plus 1.0%. The Notes contain other terms and provisions that are customary for instruments of this nature.
Rate of interest in event of default			4.00%
Additional interest percentage to prime rate in event of default			1.00%
Loan Agreement | Promissory Notes [Member] | U.S. [Member] | Minimum [Member] | Tranche One [Member]
Debt Instrument [Line Items]
Principal amount of notes triggering all sales proceeds to be applied towards repayment of notes	$ 270,000,000
Loan Agreement | Senior and Junior Tranches of Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Voluntary prepayments of debt			$ 337,500,000
Loan Agreement | Commercial Real Estate | U.S. [Member]
Debt Instrument [Line Items]
Shopping centers owned | ShoppingCenter	38
Loan Agreement | Commercial Real Estate | Puerto Rico [Member]
Debt Instrument [Line Items]
Shopping centers owned | ShoppingCenter	12
Senior Unsecured Notes with Maturity Dates Ranging from July 2018 to February 2025 [Member] | Promissory Notes [Member]
Debt Instrument [Line Items]
Repayments of senior notes			900,000,000
Payment on redemption of senior notes			28,400,000
Senior Unsecured Notes with Maturity Dates Ranging from July 2018 to February 2025 [Member] | Mortgages indebtedness [Member]
Debt Instrument [Line Items]
Repayment of outstanding mortgage debt			452,500,000
Repayment of unsecured term loan			$ 200,000,000