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Mortgage Notes Payable, Revolving Credit Facility, and Term Loan Facility (Detail) $ in Thousands		12 Months Ended
	Oct. 27, 2017	Dec. 31, 2017 USD ($) property	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Encumbered properties | property		96
Long-term debt		$ 542,627	$ 509,395
Revolving Credit Facility
Debt Instrument [Line Items]
Encumbered properties | property		29
Long-term debt		$ 20,715	39,225
Fixed rate mortgage loans
Debt Instrument [Line Items]
Encumbered properties | property		48
Carrying value		$ 383,189	378,477
Variable rate mortgage loans
Debt Instrument [Line Items]
Encumbered properties | property		19
Carrying value		$ 69,302	71,707
Mortgage Notes Payable
Debt Instrument [Line Items]
Encumbered properties | property		67
Carrying value		$ 452,491
Premiums and discounts, net		(281)	217
Deferred financing costs, net		(4,830)	(5,123)
Long-term debt		$ 447,380	445,278
Variable rate Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Encumbered properties | property		29
Carrying value		$ 21,400	39,700
Deferred financing costs, net		$ (685)	(475)
Libor rate (as percent)		1.75%
Scheduled maturity dates		Oct. 27, 2021
Variable rate Term Loan Facility
Debt Instrument [Line Items]
Carrying value		$ 75,000	25,000
Libor rate (as percent)		1.70%
Scheduled maturity dates		Oct. 27, 2022
Term Loan Facility
Debt Instrument [Line Items]
Deferred financing costs, net		$ (468)	(108)
Long-term debt		$ 74,532	$ 24,892
London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Libor rate (as percent)	2.75%	1.56%

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Number of existing encumbered properties.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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