Summary of Significant Accounting Policies - Construction in Progress (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Construction in progress	$ 69,175	$ 30,261
Park Van Ness
Property, Plant and Equipment [Line Items]
Construction in progress	63,495	26,998
Other
Property, Plant and Equipment [Line Items]
Construction in progress	$ 5,680	$ 3,263

The current amount of expenditures for a real estate project that has not yet been completed.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.10)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Phase

-URI http://asc.fasb.org/extlink&oid=49177889

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