Loans - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 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	$ 36,684	$ 167,879	300,051	554,621
Loans held in portfolio, net of unearned income	31,523,188		31,523,188		$ 29,240,557
Non-accrual with no allowance	190,430		190,430		236,858
Troubled debt restructurings	1,640,640		1,640,640		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	35,875	165,282	294,872	546,335
Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	1,488,548		1,488,548		1,468,966
Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	432,324		432,324		497,988
Non-accrual with no allowance	190,000		190,000		237,000
Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,317,074		1,317,074		1,491,093
Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	340,503		340,503		480,767
Loans held in portfolio, net of unearned income	793,922		793,922		1,028,644
Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	30,206,114		30,206,114		27,749,464
GNMA
Accounts, Notes, Loans and Financing Receivable
Repurchased loans			49,000	80,000
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	14,190	84,896	169,352	293,613
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	21,685	76,118	117,015	234,953
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		4,268	8,505	17,769
Consumer loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	135,000		349,000
Residential Mortgage
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	66,000	90,000	219,000	310,000
Mortgage Loans Sold	17,000	31,000	50,000	116,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	106,000	41,000	129,000	90,000
Purchased credit deterioration loan
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	300	1,000	4,000	13,000
Mortgages
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	7,311,713		7,311,713		7,427,196
Non-accrual with no allowance	132,300		132,300		169,856
Troubled debt restructurings	1,253,001		1,253,001		1,255,713
Mortgages | Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	1,167,237		1,167,237		1,143,204
Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	143,326		143,326		180,700
Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	936,088		936,088		1,141,082
Mortgages | Past due 90 days or more
Accounts, Notes, Loans and Financing Receivable
Accruing loans past-due 90 days or more	328,605		328,605		471,358
Loans held in portfolio, net of unearned income	602,911		602,911		827,214
Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	6,375,625		6,375,625		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	300,000		300,000		500,000
Mortgages | Guaranteed by U.S. sponsored entities | Accruing
Accounts, Notes, Loans and Financing Receivable
Troubled debt restructurings	725,000		725,000		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	9,000		9,000		13,000
Commercial Loans
Accounts, Notes, Loans and Financing Receivable
Purchase of Loans	106,000
Loans Sold	11,000	$ 35,000	54,000	$ 44,000
Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	42,000		42,000		50,000
Residential mortgage loans insured By FHA
Accounts, Notes, Loans and Financing Receivable
Non-accrual with no allowance	198,000		198,000		304,000
Puerto Rico
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	22,288,281		22,288,281		20,865,382
Non-accrual with no allowance	190,430		190,430		236,748
Puerto Rico | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	420,840		420,840		497,062
Puerto Rico | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	1,254,328		1,254,328		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	339,891		339,891		480,649
Loans held in portfolio, net of unearned income	750,106		750,106		994,938
Puerto Rico | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	21,033,953		21,033,953		19,447,236
Puerto Rico | Mortgages
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	6,055,843		6,055,843		6,251,866
Non-accrual with no allowance	132,300		132,300		169,827
Puerto Rico | Mortgages | Collateral Pledged
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	142,473		142,473		179,774
Puerto Rico | Mortgages | Past due
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	908,496		908,496		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	328,605		328,605		471,358
Loans held in portfolio, net of unearned income	581,378		581,378		805,245
Puerto Rico | Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	5,147,347		5,147,347		5,147,037
Puerto Rico | Reverse Mortgages | Current
Accounts, Notes, Loans and Financing Receivable
Loans held in portfolio, net of unearned income	42,000		42,000		50,000
Puerto Rico | Residential mortgage loans insured By FHA | Past due
Accounts, Notes, Loans and Financing Receivable
Non-accrual with no allowance	$ 198,000		$ 198,000		$ 304,000