Organization and Operation (Details)	Dec. 31, 2014 sqft item
Management Statement
Properties owned	4,327us-gaap_NumberOfRealEstateProperties
Number of U.S. states where properties are owned	49
Leasable square feet	70,700,000us-gaap_AreaOfRealEstateProperty

The number of states the entity operates in as of the balance sheet date.

No definition available.

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