Loans - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest income recognized			$ 4,000,000	$ 3,000,000
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	$ 13,759,000	$ 118,256,000	25,003,000	263,367,000
Loans held in portfolio, net of unearned income	33,030,922,000		33,030,922,000		$ 32,077,769,000
Non-accrual with no allowance	175,612,000		175,612,000		177,104,000
Accumulated loans modified to borrowers under financial difficulties					1,644,647,000
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	13,393,000	116,296,000	24,359,000	258,998,000
Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties					1,495,309,000
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	393,712,000		393,712,000		406,836,000
Non-accrual with no allowance	176,000,000		176,000,000		177,000,000
Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,155,726,000		1,155,726,000		1,294,617,000
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	273,327,000		273,327,000		351,614,000
Loans held in portfolio, net of unearned income	658,831,000		658,831,000		791,055,000
Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	31,875,196,000		31,875,196,000		30,783,152,000
GNMA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Repurchased loans			24,000,000	35,000,000
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		77,269,000	1,067,000	155,163,000
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	13,393,000	37,640,000	23,292,000	95,330,000
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	0	1,387,000	0	8,505,000
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	45,000,000	123,000,000	72,000,000	214,000,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	96,000,000	71,000,000	172,000,000	153,000,000
Mortgage Loans Sold	17,000,000	14,000,000	27,000,000	33,000,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	38,000,000	23,000,000	83,000,000	23,000,000
Purchased credit deterioration loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	300,000	1,000,000	600,000	4,000,000
Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	7,449,078,000		7,449,078,000		7,397,471,000
Non-accrual with no allowance	104,324,000		104,324,000		119,098,000
Accumulated loans modified to borrowers under financial difficulties					1,256,766,000
Mortgages | Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties					1,169,976,000
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	110,128,000		110,128,000		129,173,000
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	781,185,000		781,185,000		937,253,000
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	255,711,000		255,711,000		337,602,000
Loans held in portfolio, net of unearned income	464,507,000		464,507,000		600,481,000
Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,667,893,000		6,667,893,000		6,460,218,000
Mortgages | US Government Agency Insured Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	2,000,000,000.0		2,000,000,000.0		2,000,000,000.0
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	300,000,000		300,000,000		300,000,000
Mortgages | Guaranteed by U.S. sponsored entities | Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accumulated loans modified to borrowers under financial difficulties					725,000,000
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	7,000,000		7,000,000		14,000,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase of Loans	38,000,000
Loans Sold	34,000,000	$ 43,000,000	36,000,000	$ 43,000,000
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	39,000,000		39,000,000		42,000,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	133,000,000		133,000,000		190,000,000
Puerto Rico
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	23,120,284,000		23,120,284,000		22,546,905,000
Non-accrual with no allowance	170,014,000		170,014,000		170,484,000
Puerto Rico | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	379,376,000		379,376,000		399,047,000
Puerto Rico | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	1,100,913,000		1,100,913,000		1,213,179,000
Puerto Rico | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing loans past-due 90 days or more	273,150,000		273,150,000		351,248,000
Loans held in portfolio, net of unearned income	625,489,000		625,489,000		753,257,000
Puerto Rico | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	22,019,371,000		22,019,371,000		21,333,726,000
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	6,168,288,000		6,168,288,000		6,110,279,000
Non-accrual with no allowance	103,821,000		103,821,000		119,027,000
Puerto Rico | Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	109,215,000		109,215,000		128,069,000
Puerto Rico | Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	760,072,000		760,072,000		894,800,000
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	255,711,000		255,711,000		337,602,000
Loans held in portfolio, net of unearned income	449,930,000		449,930,000		579,993,000
Puerto Rico | Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	5,408,216,000		5,408,216,000		5,215,479,000
Puerto Rico | Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held in portfolio, net of unearned income	39,000,000		39,000,000		42,000,000
Puerto Rico | Residential mortgage loans insured By FHA | Past due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-accrual with no allowance	$ 133,000,000		$ 133,000,000		$ 190,000,000