Segment Information - Real Estate Investments, at Cost of Company's Reportable Segments (Parenthetical) (Details) - Assets Held-for-sale [Member]	Dec. 31, 2017 a
Segment Reporting Information [Line Items]
Acreage of land	13.1
Other [Member] \| Land Held For Development [Member]
Segment Reporting Information [Line Items]
Acreage of land	13.1

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