REAL ESTATE AND ACQUIRED IN PLACE LEASE VALUE - Schedule of Investments in Consolidated Properties (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Real Estate [Abstract]
Land	$ 1,330.6	$ 1,371.3
Buildings	3,630.4	3,958.4
Building improvements	469.5	652.0
Acquired in-place lease values	352.9	344.4
Real estate investment, at cost	5,783.4	6,326.1
Less accumulated depreciation and amortization	(703.2)	(623.6)
Real estate and acquired in place lease values, net of accumulated depreciation and amortization	$ 5,080.2	5,702.5
Leases, Acquired-in-Place [Member]
Real Estate Properties [Line Items]
Weighted-average lease term	7 years 1 month 6 days
Building and Building Improvements [Member] \| Maximum [Member]
Real Estate Properties [Line Items]
Estimated useful life (not to exceed)	40 years
Buildings, Building Improvements and Acquired In-Place Lease Values [Member]
Real Estate Properties [Line Items]
Depreciation and amortization expense	$ 173.4	$ 190.3	$ 198.9

Investment Buildings

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- Definition

Investment Buildings Improvements

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No definition available.

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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- Definition

This element represents the amount of value allocated by a lessor (acquirer) to lease agreements which exist at acquisition of a leased property. Such amount may include the value assigned to existing tenant relationships and excludes the market adjustment component of the value assigned for above or below-market leases acquired.

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- Definition

Amount before accumulated depletion of real estate held for productive use, excluding land held for sale.

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-Publisher FASB
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- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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- Definition

The cumulative amount of depreciation for real estate property held for investment purposes.

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- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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Amount of real estate investment property, net of accumulated depreciation, which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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