Management Statement (Details)	Mar. 31, 2014 sqft item
Management Statement
Properties owned	4,208
Number of U.S. states where properties are owned	49
Leasable square feet	66,800,000

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