Summary of Disposition of Property's (Parenthetical) (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2017 USD ($)
Copper Mill
Real Estate Properties [Line Items]
Gain (loss) on sale related to property includes defeasance costs	$ 2,748

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.

No definition available.

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Balance Type:	na
Period Type:	duration