Fair Value Disclosure of Financial Instruments - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Renovations to Existing Real Estate Assets	$ 2,187,000	$ 2,934,000
Notes Payable	1,691,253,000		1,673,848,000
Fixed Rate Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes Payable, fair value	782,300,000	777,847,000
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	731,116,000	732,382,000
Variable Rate Debt
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes Payable, fair value	882,389,000	860,051,000
Notes Payable Excluding Interest Rate Swaps and Cap Agreements	$ 960,137,000	$ 941,466,000
Minimum [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Renewal Period	30 days
Maximum [Member] | Secured Debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Renewal Period	90 days