SERVICING RIGHTS - Changes in Valuation Assumptions (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Off-balance Sheet Risks, Disclosure Information [Line Items]
Basis Points Drop in Rate, Assumption One	0.50%	0.50%
Basis Points Drop in Rate, Assumption Two	1.00%	1.00%
Mortgage servicing rights.
Off-balance Sheet Risks, Disclosure Information [Line Items]
Aggregate portfolio principal balance	$ 2,753,477	$ 2,609,776
Weighted average rate of note	3.20%	3.20%
Conditional prepayment rate	9.50%	13.80%
Conditional prepayment rate, 0.5% Adverse Change	10.50%	20.00%
Conditional prepayment rate, 1.0% Adverse Change	12.70%	31.50%
Fair value MSR	$ 32,140	$ 26,070
Fair value MSR, 0.5% Adverse Change	30,931	21,188
Fair value of MSR, 1.0% Adverse Change	$ 28,475	$ 15,348
Percentage of MSR	1.20%	1.00%
Percentage of MSR, 0.5% Adverse Change	1.10%	0.80%
Percentage of MSR, 1.0% Adverse Change	1.00%	0.60%
Discount rate	9.10%	9.10%
Discount rate, 0.5% Adverse Change	9.60%	9.60%
Discount rate, 1.0% Adverse Change	10.10%	10.10%
Fair value MSR, 0.5% Adverse Change	$ 31,464	$ 25,586
Fair value MSR, 1.0% Adverse Change	$ 30,813	$ 25,119
Percentage of MSR, 0.5% Adverse Change	1.10%	1.00%
Percentage of MSR, 1.0% Adverse Change	1.10%	1.00%