Acquisitions - Additional Information (Details) - One Front Street [Member] - California [Member]		9 Months Ended
Sep. 12, 2016 USD ($) ft²	Sep. 30, 2016
Business Acquisition [Line Items]
Agreement acquisition date		Sep. 12, 2016
Acquisition amount	$ 521,000,000
Area of Class A office building \| ft²	651,000
Other Assets [Member]
Business Acquisition [Line Items]
Non-refundable deposit	$ 50,000,000

Fair value at acquisition-date of the assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interests issued by the acquirer, including but not limited to, instruments or interests issued or issuable in consideration for the business combination.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

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Balance Type:	credit
Period Type:	duration