LOANS - Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Assets	$ 130,295,081,000	$ 105,787,527,000
Loan loss provision	16,569,000	3,496,000	$ 0
Aggregate principal balance	63,200,000	7,000,000.0
Carrying value	43,100,000	3,500,000
Balance of the loan loss provision	20,100,000	$ 3,500,000
Loans	$ 669,713,000
Loans receivable with variable rates of interest	92.00%	88.00%
Residential Mortgage Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Assets	$ 1,600,000,000	$ 1,400,000,000
Loans	$ 66,700,000	$ 97,500,000
Percent of adjustable-rate loans	36.00%	47.00%
Commercial Mortgage Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loans	$ 0	$ 42,200,000
Unfunded corporate loan commitments	181,400,000
Corporate Loans
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Loan loss provision	7,400,000
Aggregate principal balance	19,600,000
Carrying value	12,200,000
Unfunded corporate loan commitments	$ 81,200,000
Minimum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Senior secured loans, stated maturity	5 years
Maximum
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Senior secured loans, stated maturity	7 years

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Loans Receivable With Loan Loss Provision, Gross

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Percentage of adjustable-rate loans.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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A valuation allowance for financing receivables that are expected to be uncollectible.

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Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

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Amount of expense related to estimated loss from loan and lease transactions.

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Unused amount of commitments to extend credit to customers.

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