EARNINGS PER COMMON SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Numerator for basic and diluted earnings per share:
Income from continuing operations attributable to common stockholders	$ 117,820	$ 47,262
Discontinued operations	(5,627)	43,364
Net income attributable to common stockholders	$ 112,193	$ 90,626
Denominator:
Denominator for basic earnings per share - weighted average shares	291,455	288,375
Effect of dilutive securities:
Stock options (in shares)	573	512
Restricted stock awards (in shares)	120	64
OP units (in shares)	1,776	1,862
Denominator for diluted earnings per share - adjusted weighted average shares	293,924	290,813
Basic earnings per share:
Income from continuing operations attributable to common stockholders	$ 0.40	$ 0.16
Discontinued operations (in dollars per share)	$ (0.02)	$ 0.15
Net income attributable to common stockholders	$ 0.38	$ 0.31
Diluted earnings per share:
Income from continuing operations attributable to common stockholders	$ 0.40	$ 0.16
Discontinued operations	$ (0.02)	$ 0.15
Net income attributable to common stockholders	$ 0.38	$ 0.31