Acquired Intangible Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Above- Market and Below- Market Leases [Member] | Operating Income [Member]
Business Acquisition [Line Items]
Amortization from acquired leases	$ 2,067,000	$ 1,791,000	$ 1,833,000
Above- Market and Below- Market Leases [Member] | Operating Expenses [Member]
Business Acquisition [Line Items]
Amortization from acquired leases	317,000	320,000	333,000
Above- Market and Below- Market Leases [Member] | Prepaid Expenses And Other Assets [Member]
Business Acquisition [Line Items]
Finite lived intangible asset	3,500,000	3,189,000
Accumulated amortization	5,160,000	4,698,000
Above- Market and Below- Market Leases [Member] | Accounts Payable and Accrued Liabilities [Member]
Business Acquisition [Line Items]
Accumulated amortization	17,790,000	15,578,000
Finite lived intangible liabilities	21,514,000	22,714,000
In-Place Leases [Member]
Business Acquisition [Line Items]
Depreciation and amortization expense	2,866,000	1,855,000	$ 1,395,000
In-Place Leases [Member] | Prepaid Expenses And Other Assets [Member]
Business Acquisition [Line Items]
Finite lived intangible asset	38,542,000	35,704,000
Accumulated amortization	$ 9,908,000	$ 7,043,000