Segment Reporting (Details Textual)	6 Months Ended
	Jun. 30, 2012 Properties
Segment Reporting (Textual) [Abstract]
Number of properties generated by rental revenue	400
SunTrust Banks, Inc. [Member]
Segment Reporting (Textual) [Abstract]
Percentage of rental revenue	9.00%
AT&T, Inc. [Member]
Segment Reporting (Textual) [Abstract]
Percentage of rental revenue	7.00%