SEGMENT INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Revenues:
Total revenues	$ 685,846	$ 611,964	$ 1,370,472	$ 1,178,050
Net real estate property:
Total net real estate property	17,135,848		17,135,848		17,111,532
United States
Revenues:
Total revenues	662,394	588,335	1,323,640	1,130,820
Net real estate property:
Total net real estate property	16,758,149		16,758,149		16,711,508
Canada
Revenues:
Total revenues	23,452	23,629	46,832	47,230
Net real estate property:
Total net real estate property	$ 377,699		$ 377,699		$ 400,024