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Amount of increases in the provision for credit losses of collateral loans.

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Represent the discount percentage used for evaluating collateral pledged for financing transactions.

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Represents the information pertaining to the variance in percentage.

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Weighted average maturity of residential mortgages receivable, in 'PnYnMnDnTnHnMnS' format.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of allowance for loan and lease losses covered by loss sharing agreements.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

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Amount of other-than-temporary impairment (OTTI) applied to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Discount rate used to estimate the fair value of servicing assets and servicing liabilities.

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FAIR VALUE - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
FAIR VALUE - Additional Information (Details) - USD ($)	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Assets Pledged As Collateral For Loans Receivable [Line Items]
Mortgage servicing rights	$ 4,300,000
Valuation reserve	(197,000)	$ 246,000
Amortized cost	3,800,000
Servicing Asset at Fair Value, Amount	$ 4,300,000
Percentage of discount from appraised value (in hundredths)	3.63%
Weighted average maturity of residential mortgages	20 years
Prepayment Speed used in unobservable assumptions	152		204
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Qualitative Information	152		204
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate	9.40%		9.40%
Discount rate used to estimate fair value (in hundredths)	9.40%		9.40%
Subtotal	$ 4,484,767,000		$ 4,657,183,000
Valuation allowance	71,844,000	53,609,000	$ 61,408,000	$ 50,652,000
Provision for Loan and Lease Losses	815,000	142,000
Recoveries	145,000	206,000
Loans and Leases Receivable, Gross	19,600,000	17,400,000
Loans and Leases Receivable, Allowance	8,500,000	$ 7,400,000
Mortgage servicing rights, fair value	4,300,000
Mortgage servicing rights, impairment	518,000
Minimum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Amount of variance	$ 100,000
Minimum \| Commercial Real Estates \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	0.00%
Minimum \| Inventory Finished Goods \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	35.00%
Minimum \| Finished Goods \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	30.00%
Minimum \| Inventory Work In Process \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	50.00%
Minimum \| Equipment \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	30.00%
Minimum \| Marketable Securities \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	10.00%
Maximum \| Commercial Real Estates \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	50.00%
Maximum \| Inventory Finished Goods \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	65.00%
Maximum \| Finished Goods \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	60.00%
Maximum \| Inventory Work In Process \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	100.00%
Maximum \| Equipment \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	70.00%
Maximum \| Marketable Securities \| Level 3
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of discount from appraised value (in hundredths)	30.00%
Municipal Notes \| Minimum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	(5.00%)
Municipal Notes \| Maximum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	5.00%
US Government Agencies Short-term Debt Securities \| Minimum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	(3.00%)
US Government Agencies Short-term Debt Securities \| Maximum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	3.00%
U.S. Treasury securities \| Minimum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	(1.00%)
U.S. Treasury securities \| Maximum
Assets Pledged As Collateral For Loans Receivable [Line Items]
Percentage of Variance	1.00%