SEGMENT INFORMATION (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Revenues:
Total revenues	$ 884,024	$ 741,470
Net real estate property:
Total net real estate property	21,418,659		18,985,559
United States
Revenues:
Total revenues	834,458	720,107
Net real estate property:
Total net real estate property	20,016,240		17,547,255
Canada
Revenues:
Total revenues	44,050	21,218
Net real estate property:
Total net real estate property	1,158,811		1,269,710
UNITED KINGDOM
Revenues:
Total revenues	5,516	145
Net real estate property:
Total net real estate property	$ 243,608		$ 168,594