SEGMENT INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Revenues:
Total revenues	$ 616,448	$ 359,506	$ 1,187,571	$ 625,985
Net real estate property:
Net real estate property	16,723,953		16,723,953		15,913,732
United States
Revenues:
Total revenues	592,819	336,411	1,140,341	580,371
Net real estate property:
Net real estate property	16,325,712		16,325,712		15,510,824
Canada
Revenues:
Total revenues	23,629	23,095	47,230	45,613
Net real estate property:
Net real estate property	$ 398,241		$ 398,241		$ 402,908