Investments in Real Estate - Summary of Estimated Fair Values of Assets Acquired and Liabilities Assumed (Detail 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Asset acquisition capitalized acquisition costs	$ 200	$ 700	$ 300
Assets:
Land	203,826	124,660
Buildings and Improvements	147,174	106,496
Tenant improvements	5,336	4,792
Acquired lease intangible assets	21,283	16,236
Other acquired assets	527	128
Total assets acquired	378,146	252,312
Liabilities:
Acquired lease intangible liabilities	7,517	1,713
Notes payable	0	17,097
Deferred rent liability	0	977
Other assumed liabilities	2,883	1,926
Net assets acquired	10,400	21,713
Total	367,746	$ 230,599
REIT Portfolio Acquisition [Member]
Assets:
Land	101,530
Buildings and Improvements	74,586
Tenant improvements	2,875
Acquired lease intangible assets	12,103
Other acquired assets	222
Total assets acquired	191,316
Liabilities:
Acquired lease intangible liabilities	934
Other assumed liabilities	1,519
Net assets acquired	2,453
Total	$ 188,863
Below Market Lease, Weighted Average Useful Life	4 years 9 months 18 days
Other 2016 Acquisitions
Assets:
Land	$ 102,296
Buildings and Improvements	72,588
Tenant improvements	2,461
Acquired lease intangible assets	9,180
Other acquired assets	305
Total assets acquired	186,830
Liabilities:
Acquired lease intangible liabilities	6,583
Other assumed liabilities	1,364
Net assets acquired	7,947
Total	$ 178,883
Below Market Lease, Weighted Average Useful Life	10 years 3 months 18 days
Other 2015 Acquisitions
Liabilities:
Below Market Lease, Weighted Average Useful Life		5 years 10 months 24 days
In-place Lease Intangibles
Assets:
Acquired lease intangible assets		$ 12,100
In-place Lease Intangibles | REIT Portfolio Acquisition [Member]
Business Acquisition [Line Items]
Amortization period of acquired intangible assets	5 years
Assets:
Acquired lease intangible assets	$ 11,100
In-place Lease Intangibles | Other 2016 Acquisitions
Business Acquisition [Line Items]
Amortization period of acquired intangible assets	5 years 6 months
Assets:
Acquired lease intangible assets	$ 8,900
In-place Lease Intangibles | Other 2015 Acquisitions
Business Acquisition [Line Items]
Amortization period of acquired intangible assets		5 years 6 months
Above Market Tenant Leases
Assets:
Acquired lease intangible assets		$ 4,100
Above Market Tenant Leases | REIT Portfolio Acquisition [Member]
Business Acquisition [Line Items]
Amortization period of acquired intangible assets	7 years 7 months 6 days
Assets:
Acquired lease intangible assets	$ 1,000
Above Market Tenant Leases | Other 2016 Acquisitions
Business Acquisition [Line Items]
Amortization period of acquired intangible assets	2 years 4 months 24 days
Assets:
Acquired lease intangible assets	$ 300
Above Market Tenant Leases | Other 2015 Acquisitions
Business Acquisition [Line Items]
Amortization period of acquired intangible assets		11 years 10 months 24 days
Land | 9401 De Soto Ave., 16221 Arthur St., 425 Hacienda Blvd., 6020 Sheila St., and 2535 Midway
Business Acquisition [Line Items]
Asset acquisition capitalized acquisition costs		$ 400
Buildings and Improvements | 16221 Arthur St., 425 Hacienda Blvd., 6020 Sheila St., and 2535 Midway
Business Acquisition [Line Items]
Asset acquisition capitalized acquisition costs		$ 300