Properties Held for Sale and Property Dispositions - Properties Held for Sale (Details) $ in Millions	3 Months Ended
Sep. 30, 2015 USD ($)
570-574 Fifth Avenue
Property Dispositions and Assets Held for Sale
Agreed sale consideration	$ 125.4
140-150 Grand Street
Property Dispositions and Assets Held for Sale
Agreed sale consideration	32.0
Impairment Charge	$ 19.2

Amount, before tax, of (gain) loss recognized for the (reversal of write-down) write-down to fair value, less cost to sell, of a disposal group. Excludes discontinued operations.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=51719941&loc=d3e2941-110230

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=51824106&loc=d3e2443-110228

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Name:	us-gaap_DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration