SEGMENT INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Revenues:
Total revenues	$ 684,868	$ 566,424
Net real estate property:
Total net real estate property	16,995,737		17,111,532
United States
Revenues:
Total revenues	661,488	542,823
Net real estate property:
Total net real estate property	16,605,758		16,711,508
Canada
Revenues:
Total revenues	23,380	23,601
Net real estate property:
Total net real estate property	$ 389,979		$ 400,024