Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Mar. 31, 2017	Dec. 31, 2017 USD ($) $ / shares	Dec. 31, 2016 USD ($) $ / shares	Dec. 31, 2015 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Asset Impairment Charges		$ 0	$ 0	$ 0
Asset Retirement Obligation		$ 0	0	0
Investment maturity period		90 days
Insurance coverage provided to a depositor's other deposit accounts held at an FDIC-insured institution		$ 250,000
Past due rent charge term		5 days
Allowance for uncollectible accounts		$ 705,000	691,000
Bad debt expenses		2,821,000	425,000	243,000
Tenant recoveries realized from previous charge-offs		560,000	26,000	0
Finite-Lived Intangible Assets, Accumulated Amortization		41,830,000	28,550,000
Amortization of Intangible Assets		15,640,000	12,750,000	11,510,000
Percentage of Sales Rent Income		$ 199,000	289,000	163,000
Minimum percentage of taxable income to be distributed to stockholders		90.00%
Provision for federal and state income taxes		$ 15,000	107,000
Term of disqualification to be taxed as a REIT due to loss of REIT status		5 years
Property management fee percentage		3.00%
Asset management fee percentage		2.00%
Development fee percentage		5.00%
Advertising and promotion cost		$ 237,000	$ 228,000	218,000
Common stock, Par value (in usd per share) | $ / shares		$ 0.01	$ 0.01
Reverse Stock Split Conversion Ratio	0.125
Provision for Loan and Lease Losses		$ 2,821,000	$ 425,000	$ 243,000
Rent and Other Tenant Receivables, Net [Member]
Schedule Of Significant Accounting Policies [Line Items]
Unbilled rent asset, net		$ 2,340,000	$ 1,240,000
Minimum [Member] | Buildings and improvements
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful life of buildings and improvements		5 years
Maximum [Member] | Buildings and improvements
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful life of buildings and improvements		40 years
Renewed Lease [Member]
Schedule Of Significant Accounting Policies [Line Items]
Commission fee percentage		3.00%
New Lease [Member]
Schedule Of Significant Accounting Policies [Line Items]
Commission fee percentage		6.00%
Shoppes at Myrtle Park Bi-Lo [Member]
Schedule Of Significant Accounting Policies [Line Items]
Amortization of Deferred Charges		$ 1,740,000
Allowance for Tenant Receivables [Member]
Schedule Of Significant Accounting Policies [Line Items]
Bad debt expenses		$ 457,000