Supplemental Information to Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Interest Expense Capitalized in Connection with Development Activity	$ 930	$ 390
Supplemental schedule of non-cash investing and financing activities:
Distribution payable	13,825
Exchange Of Limited Partnership Units For General Partnership Units [Abstract]
Conversion of Units to Common Stock	0	0
Mortgage loan payable assumed in conjunction with a property acquisition		12,026
Write-off of fully depreciated assets	(13,890)	(13,196)
Noncontrolling Interest
Exchange Of Limited Partnership Units For General Partnership Units [Abstract]
Conversion of Units to Common Stock	0	(99)
Common Stock
Exchange Of Limited Partnership Units For General Partnership Units [Abstract]
Conversion of Units to Common Stock	0	0
Additional Paid-in Capital
Exchange Of Limited Partnership Units For General Partnership Units [Abstract]
Conversion of Units to Common Stock	0	99
Common Stock
Supplemental schedule of non-cash investing and financing activities:
Distribution payable	9,536	0
Preferred Stock
Supplemental schedule of non-cash investing and financing activities:
Distribution payable	$ 4,289	$ 5,214