Related Party Transactions Releases of Guarantees (Details) (USD $)	12 Months Ended
Dec. 31, 2013
Anthony E. and Peter L. Malkin [Member] \| Mortgages [Member]
Related Party Transaction [Line Items]
Release of guarantee	$ 1,300,000,000
Anthony E. and Peter L. Malkin [Member] \| Mortgages [Member] \| First Stamford Place [Member]
Related Party Transaction [Line Items]
Number of guarantees not released	1
Mortgages [Member] \| First Stamford Place [Member]
Related Party Transaction [Line Items]
Face amount	$ 250,000,000.0

Face (par) amount of debt instrument at time of issuance.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant