Acquired Intangible Assets - Schedule of Amortization for Acquired Intangible Assets (Detail)	Dec. 31, 2017 USD ($)
Above Market Leases [Member] | Lessor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2018	$ 124,000
2019	107,000
2020	101,000
2021	92,000
2022	83,000
Thereafter	919,000
Total	1,426,000
Below Market Leases [Member] | Lessor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2018	2,155,000
2019	2,075,000
2020	1,669,000
2021	1,495,000
2022	1,416,000
Thereafter	13,904,000
Total	22,714,000
Below Market Leases [Member] | Lessee [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2018	317,000
2019	312,000
2020	222,000
2021	157,000
2022	127,000
Thereafter	628,000
Total	1,763,000
In-Place Leases [Member] | Lessor [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2018	2,587,000
2019	2,567,000
2020	2,503,000
2021	2,474,000
2022	2,456,000
Thereafter	23,117,000
Total	$ 35,704,000