Leases - Additional Information (Detail)		3 Months Ended			6 Months Ended
	Feb. 28, 2019 USD ($) Lease Option	Jun. 30, 2019 USD ($) Property	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Jun. 30, 2019 USD ($) Property	Jun. 30, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 12, 2019 Property
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Right to recapture property space exercised		100.00%			100.00%
Number of real estate properties acquisition exercised		2			70
Number of terminated properties commenced or completed for redevelopment					40
Number of properties subject to ground lease		1			1
Number of properties subject to corporate office lease		1			1
ROU assets | $		$ 19,100,000			$ 19,100,000		$ 8,600,000
Lease liabilities | $		8,600,000			8,600,000		$ 8,600,000
Increase in ROU assets | $					$ 11,000,000.0
Operating leases expiration year					2073
General and Administrative Expenses [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Rent expense | $		401,000	$ 188,000		$ 686,000	$ 364,000
Property operating expense [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Rent expense | $		$ 11,000		$ 11,000	$ 23,000	23,000
Sears Holdings Corporation [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Right to recapture property space		100.00%			100.00%
Holdco Master Lease [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Lease expiration date	Jul. 31, 2025
Number of options for renewal of lease | Option	3
Renewal period of leases	5 years
Final option renewal period	4 years
Number of renewal term that will be increased | Lease	2
Percentage of increase annual lease rent	2.00%
Rent credit allocation description					The rent credit is allocated to specific properties based on the trailing twelve- month EBITDA of the particular property as of December 2018.
Right to recapture property space		50.00%			50.00%
Number of real estate specified properties					5
Lease termination, description					Under the terms of the Holdco Master Lease, Holdco has the right, at any time, to terminate any property upon the payment of a termination fee equal to one year of base rent plus annual taxes and other operating expenses.  Additionally, unlike the Original Master Lease, beginning in the second year of the term of the Holdco Master Lease, the tenant has the right to terminate without payment of a termination fee: (i) up to 16 properties in the second year, (ii) up to 12 properties in the third year, (iii) up to 10 properties in the fourth year, and (iv) thereafter, the remaining properties, in each instance with carry over rights if less than the maximum permitted number of properties are terminated in any lease year.  As of June 30, 2019, Holdco had not exercised any of its termination rights under the Holdco Master Lease.
Number of properties right to terminate without termination fee second year					16
Number of properties right to terminate without termination fee third year					12
Number of properties right to terminate without termination fee fourth year					10
Holdco Master Lease [Member] | Maximum [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Lease adjustment in form of rent credit | $	$ 12,000,000
Original and Holdco Master Lease [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Straight-line rental income | $		$ 1,200,000	$ (1,000,000.0)		$ 1,700,000	$ 1,800,000
Original Master Lease [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Right to recapture property space		100.00%			100.00%
Number of properties to recapture					10
Right to recapture property space exercised		100.00%			100.00%
Master Lease [Member] | Sears Holdings Corporation [Member] | Lease Terminations [Member]
Schedule Of Operating Leases Future Minimum Payments Receivable [Line Items]
Number of terminated properties announced for redevelopment								87