Supplemental Information to Statements of Cash Flows - Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Supplemental Cash Flow Information [Line Items]
Interest Expense Capitalized in Connection with Development Activity	$ 1,030	$ 3,077
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Dividend Payable	11,886
Exchange of Operating Partnership Units for Common Stock:
Conversion of Units to Common Stock	0	0
Assumption of Liabilities in Connection with the Acquisition of Real Estate	294	298
Accounts Payable Related to Construction in Progress and Additions to Investment in Real Estate	23,785	12,824
Write-off of Fully Depreciated Assets	(29,090)	(44,234)
Noncontrolling Interest
Exchange of Operating Partnership Units for Common Stock:
Conversion of Units to Common Stock	(1,697)	(943)
Common Stock
Exchange of Operating Partnership Units for Common Stock:
Conversion of Units to Common Stock	2	1
Additional Paid-in- Capital
Exchange of Operating Partnership Units for Common Stock:
Conversion of Units to Common Stock	1,695	942
Common Stock and Operating Partnership Units
Supplemental Schedule of Non-Cash Investing and Financing Activities:
Dividend Payable	$ 11,886	$ 9,788