Related Party Transactions - Schedule of fees charged to unconsolidated joint ventures (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Management fees
Related Party Transaction [Line Items]
Revenues	$ 11,052	$ 10,056	$ 32,090	$ 31,955
Unconsolidated Joint Ventures and Third Party Managed Properties
Related Party Transaction [Line Items]
Revenues	8,941	8,134	25,261	25,290
Unconsolidated Joint Ventures and Third Party Managed Properties \| Management fees
Related Party Transaction [Line Items]
Revenues	4,971	4,749	14,366	13,914
Unconsolidated Joint Ventures and Third Party Managed Properties \| Development and leasing fees
Related Party Transaction [Line Items]
Revenues	$ 3,970	$ 3,385	$ 10,895	$ 11,376

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration