Future Rental Revenues (Tables)

12 Months Ended

Dec. 31, 2011

Future Rental Revenues [Abstract]

Minimum lease payments receivable, excluding tenant reimbursements of expenses, under non-cancelable operating leases

2012	$	239,347
2013		196,288
2014		157,012
2015		125,439
2016		94,840
Thereafter		326,295
Total	$	1,139,221