Other Expenses - Schedule of General and Administrative Expenses (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2017 USD ($)
Multifamily [Member] \| Joint Venture [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Expenses related Multifamily Joint Venture.	$ 232,000

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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration