Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

Name:	us-gaap_EquityMethodInvestmentDifferenceBetweenCarryingAmountAndUnderlyingEquity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Investments in Unconsolidated Joint Ventures - Summary of Financial Information (Parenthetical) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016
712 Fifth Avenue [Member]
Schedule Of Equity Method Investments [Line Items]
Difference between carrying amount of investment and equity	$ 6,130
Oder-Center, Germany [Member]
Schedule Of Equity Method Investments [Line Items]
Difference between carrying amount of investment and equity		$ 5,017