SEGMENT INFORMATION - Revenue and Net Real Estate Property (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenues:
Total revenues	$ 943,198	$ 950,717	$ 1,955,252	$ 1,893,591
Net real estate property:
Total net real estate property	20,892,742		20,892,742		$ 21,729,087
United States
Revenues:
Total revenues	843,324	896,083	1,751,518	1,784,364
Net real estate property:
Total net real estate property	17,852,855		17,852,855		18,631,352
Canada
Revenues:
Total revenues	93,190	47,723	190,160	95,320
Net real estate property:
Total net real estate property	2,796,358		2,796,358		2,830,850
United Kingdom
Revenues:
Total revenues	6,684	$ 6,911	13,574	$ 13,907
Net real estate property:
Total net real estate property	$ 243,529		$ 243,529		$ 266,885