EARNINGS PER COMMON SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Numerator for basic and diluted earnings per share:
Income from continuing operations attributable to common stockholders, including real estate dispositions	$ 118,016	$ 120,624
Discontinued operations	3,031	(8,431)
Net income attributable to common stockholders	$ 121,047	$ 112,193
Denominator:
Denominator for basic earnings per share - weighted average shares	293,875	291,455
Effect of dilutive securities:
Stock options (in shares)	394	573
Restricted stock awards (in shares)	47	120
OP units (in shares)	1,929	1,776
Denominator for diluted earnings per share - adjusted weighted average shares	296,245	293,924
Basic earnings per share:
Income from continuing operations attributable to common stockholders, including real estate dispositions	$ 0.40	$ 0.41
Discontinued operations (in dollars per share)	$ 0.01	$ (0.03)
Net income attributable to common stockholders	$ 0.41	$ 0.38
Diluted earnings per share:
Income from continuing operations attributable to common stockholders, including real estate dispositions	$ 0.40	$ 0.41
Discontinued operations	$ 0.01	$ (0.03)
Net income attributable to common stockholders	$ 0.41	$ 0.38