COMMITMENTS AND CONTINGENCIES (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) transaction	Mar. 31, 2020 USD ($) transaction	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Guarantor Obligations [Line Items]
Provision for losses at the time of sale	$ (20,160,000)	$ 56,646,000
Allowance for credit losses	204,818,000	139,073,000	$ 228,804,000	$ 47,576,000
(Recovery of) provision for credit losses	(20,160,000)	56,646,000
Unfunded Lending Commitment
Guarantor Obligations [Line Items]
Provision for losses at the time of sale	600,000	(200,000)
Allowance for credit losses	8,900,000		$ 8,200,000
(Recovery of) provision for credit losses	600,000	$ (200,000)
Secondary Market Loan Sales
Guarantor Obligations [Line Items]
Provision for losses at the time of sale	$ 0
Number of loans repurchased | transaction	0	0
(Recovery of) provision for credit losses	$ 0