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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Common Stock and Other Equity Related Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions			6 Months Ended
	Jul. 13, 2018	Apr. 13, 2018	Jun. 30, 2018	Jul. 26, 2018
Class of Stock [Line Items]
Common stock, dividends paid (usd per share)		$ 0.550
OP units were exchanged for an equal number of shares of common stock (OP Units)			13,838
Private Placement
Class of Stock [Line Items]
Common stock, available for issuance			$ 150.0
Subsequent Event
Class of Stock [Line Items]
Common stock, dividends paid (usd per share)	$ 0.5500
Subsequent Event \| Private Placement
Class of Stock [Line Items]
Common stock, available for issuance				$ 126.8