SEGMENT INFORMATION (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Revenues:
Total revenues	$ 573,694	$ 268,432
Net real estate property:
Net real estate property	15,747,019	15,913,732	15,913,732
United States
Revenues:
Total revenues	550,093	245,913
Net real estate property:
Net real estate property	15,340,181		15,510,824
Canada
Revenues:
Total revenues	23,601	22,519
Net real estate property:
Net real estate property	$ 406,838		$ 402,908