Business (Details)	Sep. 30, 2012 state property
Business
Number of properties in which ownership interest is held by the entity	52
Number of states in which the entity owned interests in properties	19

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