NON-CONSOLIDATED VARIABLE INTEREST ENTITIES AND SERVICING ASSETS - Key Economic Assumptions Used in Determining Fair Value at Time of Sale of Loans (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Maximum [Member] | Conventional Loan [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	6.80%	7.20%	6.90%
Discount rate	10.00%	10.00%	10.00%
Maximum [Member] | Conventional Non Conforming Mortgage Loans [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	8.60%	9.20%	9.30%
Discount rate	13.70%	14.30%	14.30%
Maximum [Member] | Government-guaranteed mortgage loans [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	6.40%	6.50%	6.40%
Discount rate	12.00%	12.00%	12.00%
Minimum [Member] | Conventional Loan [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	6.60%	6.90%	6.70%
Discount rate	10.00%	10.00%	10.00%
Minimum [Member] | Conventional Non Conforming Mortgage Loans [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	8.20%	8.60%	8.90%
Discount rate	13.50%	13.70%	14.30%
Minimum [Member] | Government-guaranteed mortgage loans [Member]
Assumption For Fair Value On Securitization Date Of Interests Continued To Be Held By Transferor Servicing Assets Or Liabilities [Line Items]
Constant prepayment rate	6.30%	6.20%	6.20%
Discount rate	12.00%	12.00%	12.00%