At market sales agreement, common stock par value per share.

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At market sales agreement, compensation to sales agents.

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At market sales agreement, maximum offer price of common shares.

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At-the-market sales agreement, obligation to sell shares.

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At market sales agreement, remaining offer price of common shares.

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The value of dividends related to restricted common shares awards vested.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Date the declared dividend will be paid, in CCYY-MM-DD format.

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Date the dividend to be paid was declared, in CCYY-MM-DD format.

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Date the holder must own the stock to be entitled to the dividend, in CCYY-MM-DD format.

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The number of limited partner units outstanding.

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The cash outflow for cost incurred directly with the issuance of an equity security.

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Cash received on stock transaction after deduction of issuance costs.

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The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

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Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

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The number of shares issued during the period upon the conversion of units. An example of a convertible unit is an umbrella partnership real estate investment trust unit (UPREIT unit).

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Value of stock issued during the period upon the conversion of units. An example of a convertible unit is an umbrella partnership real estate investment trust unit (UPREIT unit).

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Shareholder Equity and Noncontrolling Interests - Additional Information (Detail) - USD ($)				3 Months Ended	9 Months Ended
	Sep. 17, 2018	Jun. 13, 2018	Mar. 13, 2018	Sep. 30, 2018	Sep. 30, 2018	Aug. 04, 2017
Class Of Stock [Line Items]
Dividends paid				$ 0	$ 181,000
At-the-market sales agreement, common stock par value per share						$ 0.01
At-the-market agreement to sell common shares, maximum offer price						$ 150,000,000
At-the-market agreement to sell common shares, compensation to sales agents						2.00%
At-the-market sales agreement, obligation to sell common shares						$ 0
At-the-market agreement to sell common shares, remaining offer price				$ 118,065,000	$ 118,065,000
Limited partnership interest received in exchange for issuance of common stock				18,108	2,130,244
Conversion of noncontrolling interest to common shares				$ 198,000	$ 14,506,000
OP Units outstanding				881,107	881,107
Common Shares
Class Of Stock [Line Items]
Conversion of noncontrolling interest to common shares (in Shares)				18,108	2,130,244
Conversion of noncontrolling interest to common shares					$ 21,000
Noncontrolling Interests
Class Of Stock [Line Items]
Conversion of noncontrolling interest to common shares					$ (14,506,000)
ATM Sales Agreement
Class Of Stock [Line Items]
Shares issued				1,861,508	1,923,164
Weighted average price per share				$ 10.32	$ 10.32
Commissions				$ 18,823,000	$ 19,445,000
Net proceeds after deducting commissions				$ 384,000	$ 397,000
Dividend Declared
Class Of Stock [Line Items]
Declaration date	Sep. 17, 2018	Jun. 13, 2018	Mar. 13, 2018
Dividend declared per share	$ 0.18	$ 0.18	$ 0.18
Payment date	Oct. 19, 2018	Jul. 20, 2018	Apr. 20, 2018
Record date	Oct. 05, 2018	Jul. 06, 2018	Apr. 04, 2018
Dividend Declared \| Noncontrolling Interests
Class Of Stock [Line Items]
Declaration date	Sep. 17, 2018	Jun. 13, 2018	Mar. 13, 2018
Dividend declared per share	$ 0.18	$ 0.18	$ 0.18
Payment date	Oct. 19, 2018	Jul. 20, 2018	Apr. 20, 2018
Record date	Oct. 05, 2018	Jul. 06, 2018	Apr. 04, 2018