COMMITMENTS AND CONTINGENT LIABILITIES - Allowance for Unfunded Commitments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Balance at beginning of period	$ 38,189	$ 28,819	$ 25,791
Provision for loan losses	125,488	19,758	16,667
Balance at end of period	199,422	38,189	28,819
Unfunded Loan Commitment
Loss Contingencies [Line Items]
Balance at beginning of period	1,077	0
Addition due to acquisition	0	1,077
Provision for loan losses	19,063	0
Balance at end of period	32,854	1,077	$ 0
Unfunded Loan Commitment | Cumulative Effect, Period of Adoption, Adjustment
Loss Contingencies [Line Items]
Balance at beginning of period	$ 12,714
Balance at end of period		$ 12,714