Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended		6 Months Ended
	Jun. 11, 2015 JointVenture	Jun. 30, 2018 USD ($) Property State	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) Property JointVenture State Segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments | Segment				1
Impairment loss on real estate assets		$ 0	$ 0	$ 0	$ 0
Impairment loss		0	0	0	0
Restricted cash		166,458,000	172,563,000	166,458,000	172,563,000	$ 175,665,000
Prepaid rental income		$ 3,500,000		$ 3,500,000		2,700,000
Revenue performance obligation satisfied over time method used description				Management determined that property and asset management and construction and development management services each represent a series of stand-ready performance obligations satisfied over time with each day of service being a distinct performance obligation.
Number of wholly owned properties acquired | Property		222		222
Number of joint venture properties acquired | JointVenture				26
Number of states in properties located | State		49		49
Decrease to net cash provided by operating activities				$ (16,205,000)	(21,700,000)
Decrease to net cash used in investing activities				$ 5,059,000	113,607,000
ASU 2016-15 [Member]
Summary Of Significant Accounting Policies [Line Items]
Decrease to net cash provided by operating activities					7,515,000
Decrease to net cash used in investing activities					7,515,000
ASU 2014-09 [Member] | Santa Monica, CA [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of interests sold		49.90%		49.90%
ASU 2014-09 [Member] | West Hartford, CT [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of interests sold		50.00%		50.00%
Interest Rate Cap [Member]
Summary Of Significant Accounting Policies [Line Items]
Interest rate caps purchased		$ 5,000,000		$ 5,000,000
Derivative, term of contract				4 years
Notional amount		1,261,000,000		$ 1,261,000,000
Derivative strike rate				3.50%
Derivative losses		$ 200,000	$ 100,000	$ 7,000	$ 600,000
Master Lease [Member]
Summary Of Significant Accounting Policies [Line Items]
Right to recapture property space		50.00%		50.00%
Sears Holdings Corporation [Member]
Summary Of Significant Accounting Policies [Line Items]
Right to recapture property space		100.00%		100.00%
Number of joint venture properties acquired | JointVenture	3
Sears Holdings Corporation [Member] | Master Lease [Member]
Summary Of Significant Accounting Policies [Line Items]
Right to recapture property space		100.00%		100.00%
Management and Other Fee Income [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue earned from unconsolidated joint ventures				100.00%
Restricted Cash Reserves [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 136,500,000		$ 136,500,000		151,300,000
Basic Property Carrying Costs [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash		$ 26,500,000		$ 26,500,000		$ 21,700,000
Operating Partnership [Member] | ESL [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of operating partnership interest held by parent		63.90%		63.90%