Operating Leases (Details Textual)	9 Months Ended
	Sep. 30, 2012
Operating Leases (Textual) [Abstract]
Years, minimum term range of office and retail leases	3 years
Years, maximum term range of office and retail leases	10 years
Months, minimum term of apartment leases	7 months
Months, maximum term of apartment leases	15 months
Months, future minimum rentals exclude residential leases	12 months