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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Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Acquisitions - Additional Information (Details) - Property	Jun. 30, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Number of multifamily properties		32
Multifamily Properties
Business Acquisition [Line Items]
Number of multifamily properties	39