Fair value of financial instruments - Carrying or notional amounts and estimated fair values for financial instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Financial Assets:
Cash and due from banks	$ 469,501	$ 428,433
Money market investments	5,614,595	17,536,719
Debt securities available-for-sale	17,804,374	24,968,269
Debt securities held-to-maturity	8,518,455	71,365
Equity securities:
Equity securities, at lower of cost or realizable value	195,854	189,977
Loans held in portfolio	31,357,467	28,545,191
Mortgage servicing rights	128,350	121,570	$ 118,395
Deposits
Time deposits	6,781,401	6,712,149
Deposits	61,227,227	67,005,088
Assets sold under agreements to repurchase	148,609	91,603
Other short-term borrowings	365,000	75,000
Notes payable:
Notes payable	886,710	988,563
Derivatives	17,000	22,878
US Treasury Securities
Financial Assets:
Debt securities available-for-sale	11,180,948	15,859,030
Debt securities held-to-maturity	8,453,467
Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	59,010	65,380
Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities available-for-sale	165,196	221,265
Debt securities held-to-maturity	19	25
Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	5,959	5,960
Other
Financial Assets:
Debt securities available-for-sale	1,060	128
Carrying amount
Financial Assets:
Cash and due from banks	469,501	428,433
Money market investments	5,614,595	17,536,719
Trading account debt securities, excluding derivatives	27,723	29,711
Debt securities available-for-sale	17,804,374	24,968,269
Debt securities held-to-maturity	8,518,455	71,365
Equity securities:
FHLB stock	65,861	59,918
FRB stock	96,206	96,217
Other investments	33,787	33,842
Equity securities, at lower of cost or realizable value	195,854	189,977
Loans held-for-sale	5,381	59,168
Loans held in portfolio	31,357,467	28,545,191
Mortgage servicing rights	128,350	121,570
Derivatives	19,229	26,093
Deposits
Demand deposits	54,445,825	60,292,939
Time deposits	6,781,402	6,712,149
Deposits	61,227,227	67,005,088
Assets sold under agreements to repurchase	148,609	91,603
Other short-term borrowings	365,000	75,000
Notes payable:
FHLB advances	389,282	492,429
Unsecured senior debt securities	299,109	297,842
Junior subordinated deferrable interest debentures (related to trust preferred securities)	198,319	198,292
Notes payable	886,710	988,563
Derivatives	17,000	22,878
Contingent consideration		9,241
Carrying amount | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	8,453,467
Carrying amount | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	59,010	65,380
Carrying amount | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	19	25
Carrying amount | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	5,959	5,960
Fair Value
Financial Assets:
Cash and due from banks	469,501	428,433
Money market investments	5,614,595	17,536,719
Trading account debt securities, excluding derivatives	27,723	29,711
Debt securities available-for-sale	17,804,374	24,968,269
Debt securities held-to-maturity	8,440,196	83,368
Equity securities:
FHLB stock	65,861	59,918
FRB stock	96,206	96,217
Other investments	34,598	36,210
Equity securities, at lower of cost or realizable value	196,665	192,345
Loans held-for-sale	5,404	59,885
Loans held in portfolio	29,366,365	27,489,583
Mortgage servicing rights	128,350	121,570
Derivatives	19,229	26,093
Deposits
Demand deposits	54,445,825	60,292,939
Time deposits	6,464,943	6,647,301
Deposits	60,910,768	66,940,240
Assets sold under agreements to repurchase	148,566	91,602
Other short-term borrowings	365,000	75,000
Notes payable:
FHLB advances	361,951	496,091
Unsecured senior debt securities	300,027	319,296
Junior subordinated deferrable interest debentures (related to trust preferred securities)	173,938	201,879
Notes payable	835,916	1,017,266
Derivatives	17,000	22,878
Contingent consideration		9,241
Fair Value | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	8,372,601
Fair Value | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	61,617	77,383
Fair Value | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	19	25
Fair Value | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	5,959	5,960
Fair Value | Level 1
Financial Assets:
Cash and due from banks	469,501	428,433
Money market investments	5,607,937	17,530,640
Trading account debt securities, excluding derivatives	13,069	6,530
Debt securities available-for-sale	1,908,589	0
Debt securities held-to-maturity	0	0
Equity securities:
FHLB stock	0	0
FRB stock	0	0
Other investments	0	0
Equity securities, at lower of cost or realizable value	0	0
Loans held-for-sale	0	0
Loans held in portfolio	0	0
Mortgage servicing rights	0	0
Derivatives	0	0
Deposits
Demand deposits	0	0
Time deposits	0	0
Deposits	0	0
Assets sold under agreements to repurchase	0	0
Other short-term borrowings	0	0
Notes payable:
FHLB advances	0	0
Unsecured senior debt securities	0	0
Junior subordinated deferrable interest debentures (related to trust preferred securities)	0	0
Notes payable	0	0
Derivatives	0	0
Contingent consideration		0
Fair Value | Level 1 | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	0
Fair Value | Level 1 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | Level 1 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | Level 1 | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | Level 2
Financial Assets:
Cash and due from banks	0	0
Money market investments	6,658	6,079
Trading account debt securities, excluding derivatives	14,119	22,703
Debt securities available-for-sale	15,894,074	24,967,443
Debt securities held-to-maturity	8,378,560	5,960
Equity securities:
FHLB stock	65,861	59,918
FRB stock	96,206	96,217
Other investments	29,302	32,429
Equity securities, at lower of cost or realizable value	191,369	188,564
Loans held-for-sale	0	0
Loans held in portfolio	0	0
Mortgage servicing rights	0	0
Derivatives	19,229	26,093
Deposits
Demand deposits	54,445,825	60,292,939
Time deposits	6,464,943	6,647,301
Deposits	60,910,768	66,940,240
Assets sold under agreements to repurchase	148,566	91,602
Other short-term borrowings	365,000	75,000
Notes payable:
FHLB advances	361,951	496,091
Unsecured senior debt securities	300,027	319,296
Junior subordinated deferrable interest debentures (related to trust preferred securities)	173,938	201,879
Notes payable	835,916	1,017,266
Derivatives	17,000	22,878
Contingent consideration		0
Fair Value | Level 2 | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	8,372,601
Fair Value | Level 2 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | Level 2 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | Level 2 | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	5,959	5,960
Fair Value | Level 3
Financial Assets:
Cash and due from banks	0	0
Money market investments	0	0
Trading account debt securities, excluding derivatives	535	478
Debt securities available-for-sale	1,711	826
Debt securities held-to-maturity	61,636	77,408
Equity securities:
FHLB stock	0	0
FRB stock	0	0
Other investments	4,966	3,704
Equity securities, at lower of cost or realizable value	4,966	3,704
Loans held-for-sale	5,404	59,885
Loans held in portfolio	29,366,365	27,489,583
Mortgage servicing rights	128,350	121,570
Derivatives	0	0
Deposits
Demand deposits	0	0
Time deposits	0	0
Deposits	0	0
Assets sold under agreements to repurchase	0	0
Other short-term borrowings	0	0
Notes payable:
FHLB advances	0	0
Unsecured senior debt securities	0	0
Junior subordinated deferrable interest debentures (related to trust preferred securities)	0	0
Notes payable	0	0
Derivatives	0	0
Contingent consideration		9,241
Fair Value | Level 3 | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	0
Fair Value | Level 3 | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	61,617	77,383
Fair Value | Level 3 | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	19	25
Fair Value | Level 3 | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | NAV
Financial Assets:
Cash and due from banks	0	0
Money market investments	0	0
Trading account debt securities, excluding derivatives	0	0
Debt securities available-for-sale	0	0
Debt securities held-to-maturity	0	0
Equity securities:
FHLB stock	0	0
FRB stock	0	0
Other investments	330	77
Equity securities, at lower of cost or realizable value	330	77
Loans held-for-sale	0	0
Loans held in portfolio	0	0
Mortgage servicing rights	0	0
Derivatives	0	0
Deposits
Demand deposits	0	0
Time deposits	0	0
Deposits	0	0
Assets sold under agreements to repurchase	0	0
Other short-term borrowings	0	0
Notes payable:
FHLB advances	0	0
Unsecured senior debt securities	0	0
Junior subordinated deferrable interest debentures (related to trust preferred securities)	0	0
Notes payable	0	0
Derivatives	0	0
Contingent consideration		0
Fair Value | NAV | US Treasury Securities
Financial Assets:
Debt securities held-to-maturity	0
Fair Value | NAV | Obligations of Puerto Rico, States and political subdivisions
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | NAV | Collateralized Mortgage Obligations - Federal agencies
Financial Assets:
Debt securities held-to-maturity	0	0
Fair Value | NAV | Securities in wholly owned statutory business trusts
Financial Assets:
Debt securities held-to-maturity	$ 0	$ 0