Schedule III Real Estate and Accumulated Depreciation (Tables)

12 Months Ended

Dec. 31, 2011

Real Estate and Accumulated Depreciation Disclosure [Abstract]

Reconciliation Of Carrying Amount Of Real Estate [Table Text Block]

Transactions in real estate and accumulated depreciation during 2011, 2010, and 2009 are summarized as follows:

	2011			2010			2009
Land, buildings, and leasehold interests:
Balance at the beginning of year	$	2,774,947		$	2,584,947		$	2,605,288
Acquisitions, completed construction and tenant improvements	772,073			248,438			35,924
Disposition of land, buildings, and leasehold interests	(14,744		)	(58,438		)	(21,751		)
Provision for loss on impairment of real estate	431			$	—		34,514
Balance at the close of year	$	3,531,845		$	2,774,947		$	2,584,947
Accumulated depreciation and amortization:
Balance at the beginning of year	$	222,921		$	183,949		$	146,289
Disposition of land, buildings, and leasehold interests	(3,010		)	(2,071		)	(3,143		)
Depreciation and amortization expense	50,710			41,043			40,803
Balance at the close of year	$	270,621		$	222,921		$	183,949