EQUITY - Additional Information (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended		27 Months Ended
	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Aug. 31, 2012 Class I Cumulative Redeemable Preferred Stock [Member]	Aug. 31, 2012 Class J Cumulative Redeemable Preferred Stock	Sep. 30, 2012 Class J Cumulative Redeemable Preferred Stock
Equity [Line Items]
Preferred stock dividend rate						7.50%	6.50%	6.50%
Issue of cumulative redeemable preferred shares							$ 200,000,000
Cumulative redeemable preferred shares redemption price per share						$ 25.1875	$ 25.00
Preferred share, stated value							$ 500.00
Redemption price per share						$ 25.00
Accrued and unpaid dividends per share						$ 0.1875
Write-off of preferred share original issuance cost		5,804,000	0	5,804,000	6,402,000	5,800,000
Common shares issued		7.9		12.7
Gross proceeds		120,000,000		190,000,000
Common equity program, generating gross proceeds per share		$ 15.14		$ 14.95
Acquisition of joint venture partners' ownership interest-number of centers				4
Proceeds from issuance of common shares	$ 231,200,000
Aggregate number of shares issued as per forward sale agreement	19.0