Commitments and Contingencies - Legacy Corner Apartments (Details) $ in Thousands	12 Months Ended
Dec. 31, 2017 USD ($)
Legacy Corner Apartments Litigation
Loss Contingencies [Line Items]
Loss contingency accrual, payments	$ 553

Amount of cash outflow reducing loss contingency liability.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration