LOAN SERVICING - Sensitivity of Fair Value to Changes in key Assumptions (Detail) - Mortgage Servicing Rights [Member] - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Weighted average life (months)	70 months 15 days	66 months 17 days
Constant prepayment rate (annualized)	12.80%	13.40%
Discount rate	9.50%	9.50%
Sensitivity analysis of fair value, change in interest rates, plus .25%	$ 3	$ 2
Sensitivity analysis of fair value, change in interest rates, plus .50%	5	4
Sensitivity analysis of fair value, change in interest rates, minus .25%	(3)	(2)
Sensitivity analysis of fair value, change in interest rates, minus .50%	$ (6)	$ (3)