DERIVATIVES - Derivative Financial Instruments, Average Remaining Maturity and the Weighted-Average Interest Rates being Paid and Received (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative, Notional Amount	$ 7,164,776	$ 2,719,980
Derivative Asset	148,071	29,189
Derivative Liability	$ (148,101)	(29,188)
Average Maturity (years)	3 years 3 months 18 days
Fair Value	$ (30)
Interest Rate Swap \| Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Derivative, Notional Amount	$ 1,790,433
Average Maturity (years)	6 years 1 month 6 days
Fair Value	$ 92,398
Interest Rate Swap \| Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Derivative, Notional Amount	$ 1,790,433
Average Maturity (years)	6 years 1 month 6 days
Fair Value	$ (92,428)
Foreign Exchange [Member] \| Derivative Financial Instruments Receive Fixed Pay Variable
Derivative [Line Items]
Derivative, Notional Amount	$ 1,791,955
Average Maturity (years)	6 months
Fair Value	$ 7,493
Foreign Exchange [Member] \| Derivative Financial Instruments Receive Variable Pay Fixed
Derivative [Line Items]
Derivative, Notional Amount	$ 1,791,955
Average Maturity (years)	6 months
Fair Value	$ (7,493)
Accrued interest and other assets \| Fair Value Hedges \| Matched interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount	1,790,433	1,359,990
Derivative Asset	95,465	17,402
Derivative Liability	(3,067)	(11,787)
Accrued interest and other assets \| Foreign Exchange [Member] \| Matched interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount	1,791,955	0
Derivative Asset	28,516	0
Derivative Liability	(21,023)	0
Accrued interest and other liabilities \| Fair Value Hedges \| Matched interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount	1,790,433	1,359,990
Derivative Asset	3,067	11,787
Derivative Liability	(95,495)	(17,401)
Accrued interest and other liabilities \| Foreign Exchange [Member] \| Matched interest rate swaps
Derivative [Line Items]
Derivative, Notional Amount	1,791,955	0
Derivative Asset	21,023	0
Derivative Liability	$ (28,516)	$ 0

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

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-Publisher FASB
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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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- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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