NATURE OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loans Held for Investments (Detail) $ in Thousands, ₩ in Millions	12 Months Ended
	Dec. 31, 2023 KRW (₩)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Financing Receivable, Past Due [Line Items]
Threshold period past due of financing receivables to be considered nonperforming	90 days
Troubled debt restructurings sustained performance period	6 months
Loans held for investment		$ 12,185,483	$ 11,552,825
Residential Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 2,821,726	2,847,290
Loans foreclosure delinquency threshold	120 days
Threshold period past due, writeoff	180 days	180 days
Threshold period past due, considered collateral dependent	180 days
Residential Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 32,239	42,772
Residential Portfolio Segment [Member] | Puerto Rico Housing Finance Authority [Member]
Financing Receivable, Past Due [Line Items]
Period of guaranteed residential mortgage loans that are no longer accruing interest	90 days
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member]
Financing Receivable, Past Due [Line Items]
Period of guaranteed residential mortgage loans that are no longer accruing interest	15 months
Loans held for investment		100,236	118,158
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		0	0
Residential Portfolio Segment [Member] | FHA/VA government-guaranteed loans [Member] | Puerto Rico Housing Finance Authority [Member]
Financing Receivable, Past Due [Line Items]
Past due 90 days and still accruing	90 days
Commercial Portfolio Segment [Member] | Mortgage Receivable [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		2,317,083	2,358,851
Commercial Portfolio Segment [Member] | Commercial And Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		3,174,232	2,886,263
Commercial Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		214,777	132,953
Commercial Portfolio Segment [Member] | Commercial and Construction Loans [Member] | Minimum [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment | ₩	₩ 0.5
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		3,657,665	3,327,468
Consumer Portfolio Segment [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		22,444	14,806
Consumer Portfolio Segment [Member] | Automobile Loan [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		1,936,256	1,798,071
Consumer Portfolio Segment [Member] | Automobile Loan [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		15,568	10,672
Consumer Portfolio Segment [Member] | Personal Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 381,275	353,246
Threshold period past due, writeoff	120 days	120 days
Consumer Portfolio Segment [Member] | Personal Loans [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 1,841	1,248
Consumer Portfolio Segment [Member] | Other Loans [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		154,107	146,190
Consumer Portfolio Segment [Member] | Other Loans [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		1,748	1,241
Consumer Portfolio Segment [Member] | Finance Leases [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		856,815	718,230
Consumer Portfolio Segment [Member] | Finance Leases [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		3,287	1,645
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 329,212	311,731
Threshold period past due, writeoff	180 days	180 days
Consumer Portfolio Segment [Member] | Credit Card Receivables [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Past Due [Line Items]
Loans held for investment		$ 0	$ 0