Organization (Details)	Mar. 31, 2017 property
Operating property
Operating Properties
Number of properties in greater New York City metropolitan area (in property)	7

The number of real estate properties owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant