Loans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable
Interest income recognized			$ 3,000	$ 4,000
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	$ 118,256	$ 195,665	263,367	386,742
Loans held in portfolio, net of unearned income	30,370,936		30,370,936		$ 29,240,557
Non-accrual with no allowance	203,069		203,069		236,858
Troubled debt restructurings	1,649,158		1,649,158		1,656,822
Trading account debt securities
Accounts, Notes, Loans and Financing Receivable
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	116,296	192,785	258,998	381,053
Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	1,486,072		1,486,072		1,468,966
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	455,900		455,900		497,988
Non-accrual with no allowance	203,000		203,000		237,000
Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,331,120		1,331,120		1,491,093
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	407,298		407,298		480,767
Loans held in portfolio, net of unearned income	885,222		885,222		1,028,644
Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	29,039,816		29,039,816		27,749,464
GNMA
Accounts, Notes, Loans and Financing Receivable
Repurchased loans			35,000	65,000
GNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	77,269	106,729	155,163	208,717
FNMA | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	37,640	72,555	95,330	158,835
FHLMC | Trading account debt securities
Accounts, Notes, Loans and Financing Receivable
Transfers Of Financial Assets Accounted For As Sale Initial Fair Value Of Assets Obtained As Proceeds	1,387	13,501	8,505	13,501
Consumer loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	123,000		214,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	71,000	94,000	153,000	220,000
Mortgage Loans Sold	14,000	19,000	33,000	85,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	23,000	28,000	23,000	49,000
Purchased credit deterioration loan
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	1,000	5,000	4,000	12,000
Mortgages
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	7,261,955		7,261,955		7,427,196
Non-accrual with no allowance	146,342		146,342		169,856
Troubled debt restructurings	1,253,778		1,253,778		1,255,713
Mortgages | Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	1,160,469		1,160,469		1,143,204
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	160,214		160,214		180,700
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,001,478		1,001,478		1,141,082
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	397,087		397,087		471,358
Loans held in portfolio, net of unearned income	701,949		701,949		827,214
Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	6,260,477		6,260,477		6,286,114
Mortgages | US Government Agency Insured Loans
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,900,000		1,900,000		1,900,000
Mortgages | US Government Agency Insured Loans | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	400,000		400,000		500,000
Mortgages | Guaranteed by us sponsored entities | Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	724,000		724,000		716,000
Mortgages | GNMA | Buy Back Option Program | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	11,000		11,000		13,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	23,000
Loans Sold	43,000	$ 2,000	43,000	$ 9,000
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	43,000		43,000		50,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	237,000		237,000		304,000
Puerto Rico
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	21,481,657		21,481,657		20,865,382
Non-accrual with no allowance	203,049		203,049		236,748
Puerto Rico | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	454,979		454,979		497,062
Puerto Rico | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,271,812		1,271,812		1,418,146
Puerto Rico | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	406,722		406,722		480,649
Loans held in portfolio, net of unearned income	851,553		851,553		994,938
Puerto Rico | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	20,209,845		20,209,845		19,447,236
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	6,041,923		6,041,923		6,251,866
Non-accrual with no allowance	146,322		146,322		169,827
Puerto Rico | Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	159,293		159,293		179,774
Puerto Rico | Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	976,138		976,138		1,104,829
Puerto Rico | Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	397,087		397,087		471,358
Loans held in portfolio, net of unearned income	681,757		681,757		805,245
Puerto Rico | Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	5,065,785		5,065,785		5,147,037
Puerto Rico | Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	43,000		43,000		50,000
Puerto Rico | Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	$ 237,000		$ 237,000		$ 304,000