Loans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized	$ 3,000	$ 4,000
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	2,250	11,244
Loans held in portfolio, net of unearned income	35,118,738		$ 35,064,971
Non-accrual with no allowance	143,027		125,958
Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	2,205	10,966
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	327,865		341,279
Non-accrual with no allowance	143,000		126,000
Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,271,848		1,348,071
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	247,542		268,471
Loans held in portfolio, net of unearned income	601,669		626,082
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	33,846,890		33,716,900
GNMA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repurchased loans	10,000	18,000
GNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	1,100	1,067
FNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	1,105	9,899
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans		27,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans Sold	11,000	10,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	56,000	45,000
Commercial and construction loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Sold	12,000	2,000
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	86,000	$ 76,000
Loans held in portfolio, net of unearned income	7,783,662		7,695,917
Non-accrual with no allowance	83,033		84,797
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	81,527		86,416
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	800,456		859,537
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	218,589		241,422
Loans held in portfolio, net of unearned income	413,133		427,719
Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,983,206		6,836,380
Mortgages | US Government Agency Insured Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	2,300,000		2,200,000
Mortgages | US Government Agency Insured Loans | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	218,700		241,600
Mortgages | GNMA | Buy Back Option Program | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	10,000		11,000
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	37,000		38,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	93,000		106,000
Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	24,634,769		24,510,923
Non-accrual with no allowance	128,916		121,961
Puerto Rico | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	310,537		329,604
Puerto Rico | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,134,872		1,204,964
Puerto Rico | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	247,331		268,362
Loans held in portfolio, net of unearned income	545,925		597,080
Puerto Rico | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	23,499,897		23,305,959
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,483,551		6,391,824
Non-accrual with no allowance	82,843		84,677
Puerto Rico | Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	80,487		85,113
Puerto Rico | Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	746,294		791,707
Puerto Rico | Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	218,589		241,422
Loans held in portfolio, net of unearned income	385,062		416,528
Puerto Rico | Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	5,737,257		5,600,117
Puerto Rico | Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	37,000		38,000
Puerto Rico | Residential mortgage loans insured By FHA | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	$ 93,000		$ 106,000