Loans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized	$ 4,000	$ 4,000
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	11,244	145,111
Loans held in portfolio, net of unearned income	32,338,373		$ 32,077,769
Non-accrual with no allowance	176,722		177,104
Accumulated loans modified to borrowers under financial difficulties			1,644,647
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	10,966	142,702
Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties			1,495,309
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	373,087		406,836
Non-accrual with no allowance	176,000		177,000
Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,244,081		1,294,617
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	305,883		351,614
Loans held in portfolio, net of unearned income	718,266		791,055
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	31,094,292		30,783,152
GNMA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repurchased loans	18,000	19,000
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	1,067	77,894
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	9,899	57,690
FHLMC | 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		7,118
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	27,000	91,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Mortgage Loans Sold	10,000	19,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	45,000
Purchased credit deterioration loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans		3,000
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	76,000	82,000
Loans held in portfolio, net of unearned income	7,405,907		7,397,471
Non-accrual with no allowance	103,543		119,098
Accumulated loans modified to borrowers under financial difficulties			1,256,766
Mortgages | Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties			1,169,976
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	106,943		129,173
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	818,927		937,253
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	291,677		337,602
Loans held in portfolio, net of unearned income	530,471		600,481
Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,586,980		6,460,218
Mortgages | US Government Agency Insured Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	2,000,000		2,000,000
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	300,000		300,000
Mortgages | Guaranteed by U.S. sponsored entities | Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties			725,000
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	7,000		14,000
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	40,000		42,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	167,000		190,000
Commercial and construction loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Sold	2,000	$ 1,000
Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	22,806,512		22,546,905
Non-accrual with no allowance	171,400		170,484
Puerto Rico | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	365,143		399,047
Puerto Rico | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,128,143		1,213,179
Puerto Rico | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	305,638		351,248
Loans held in portfolio, net of unearned income	684,617		753,257
Puerto Rico | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	21,678,369		21,333,726
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,116,684		6,110,279
Non-accrual with no allowance	103,316		119,027
Puerto Rico | Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	106,168		128,069
Puerto Rico | Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	780,668		894,800
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	291,677		337,602
Loans held in portfolio, net of unearned income	515,752		579,993
Puerto Rico | Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	5,336,016		5,215,479
Puerto Rico | Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	40,000		42,000
Puerto Rico | Residential mortgage loans insured By FHA | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	$ 167,000		$ 190,000