Basis of Presentation (Details Textual)	Dec. 31, 2011	Dec. 31, 2010
Basis of Presentation (Textual) [Abstract]
Common ownership interest	94.30%	92.80%
Noncontrolling interest represents the aggregate partnership interest in the Operating Partnership held by the limited partners	5.70%	7.20%

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

No definition available.

Name:	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant