REAL ESTATE AND ACQUIRED IN PLACE LEASE VALUE - Gains on Real Estate (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($) property
Real Estate [Line Items]
Consolidated | $	$ 434.9	$ 369.6	$ 258.0
NCI | $	116.7	70.6	43.3
Net of NCI | $	$ 318.2	$ 299.0	$ 214.7
Commercial [Member] | United Kingdom [Member]
Real Estate [Line Items]
Number of real estate properties sold	11	26	25
Commercial [Member] | Ireland [Member]
Real Estate [Line Items]
Number of real estate properties sold		3	3
Commercial [Member] | Italy [Member]
Real Estate [Line Items]
Number of real estate properties sold		2
Multifamily [Member] | Ireland [Member]
Real Estate [Line Items]
Number of real estate properties sold		6
Multifamily [Member] | United States [Member]
Real Estate [Line Items]
Number of real estate properties sold	1	3	3
Hotel [Member] | United Kingdom [Member]
Real Estate [Line Items]
Number of real estate properties sold	1
Hotel [Member] | Ireland [Member]
Real Estate [Line Items]
Number of real estate properties sold	1
Hotel [Member] | United States [Member]
Real Estate [Line Items]
Number of real estate properties sold	1
Retail Property [Member] | United States [Member]
Real Estate [Line Items]
Number of real estate properties sold	5
Retail Property [Member] | Spain [Member]
Real Estate [Line Items]
Number of real estate properties sold	10
Residential Property [Member] | United Kingdom [Member]
Real Estate [Line Items]
Number of real estate properties sold			1
Residential Property [Member] | Ireland [Member]
Real Estate [Line Items]
Number of real estate properties sold		1
Residential Property [Member] | United States [Member]
Real Estate [Line Items]
Number of real estate properties sold		1
Residential Property [Member] | Spain [Member]
Real Estate [Line Items]
Number of real estate properties sold			1
Retail [Member] | United States [Member]
Real Estate [Line Items]
Number of real estate properties sold			1
Development Project [Member] | United Kingdom [Member]
Real Estate [Line Items]
Number of real estate properties sold			1
Condominium Unit [Member] | Spain [Member]
Real Estate [Line Items]
Number of real estate properties sold			2