Changes In Accumulated Depreciation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Real Estate and Accumulated Depreciation [Line Items]
Beginning Balance	$ 700,665		$ 629,768		$ 561,104
Depreciation expense	85,234	[1]	72,128	[1]	72,419	[1]
Amortization of in-place leases	28,479
Dispositions and other	(452)		(1,231)		(3,755)
Ending Balance	$ 813,926		$ 700,665		$ 629,768

[1] Includes approximately $4.3 million, $2.8 million and $2.4 million of depreciation from rental operations included in Ancillary services revenues, net for the years ended December 31, 2011, 2010 and 2009, respectively.